Rules for the Classification of Ships Operating in Polar ... · 7.2 In any case, the Society’s...

Rules for the Classification of Ships Operating in

Polar Waters and Icebreakers

January 2017

Rule Note NR 527 DT R03 E

Marine & Offshore 92571 Neuilly sur Seine Cedex – France

Tel: + 33 (0)1 55 24 70 00 – Fax: + 33 (0)1 55 24 70 25 Website: http://www.veristar.com

Email: [email protected] 2017 Bureau Veritas - All rights reserved

Bur

eau

Ver

itas

M

arin

e &

O

ffsho

re

Gen

eral

Con

ditio

ns

care

fully

follo

wed

at a

ll tim

es b

y th

e C

lient

. 2.

12 “

Ser

vice

s” m

eans

the

ser

vice

s se

t ou

t in

cla

uses

2.2

and

2.3

bu

t al

so o

ther

ser

vice

s re

late

d to

Cla

ssifi

catio

n an

d C

ertif

icat

ion

such

as,

but

not

lim

ited

to:

ship

and

com

pany

saf

ety

man

age

men

t ce

rtifi

catio

n, s

hip

and

port

sec

urity

cer

tific

atio

n, t

rain

ing

activ

ities

, all

activ

ities

and

dut

ies

inci

dent

al t

here

to s

uch

as d

ocum

enta

tion

on

any

supp

ortin

g m

eans

, so

ftwar

e, i

nstr

umen

tatio

n, m

easu

rem

ents

, te

sts

and

tria

ls o

n bo

ard.

2.

13 “

Soc

iety

” m

eans

the

cla

ssifi

catio

n so

ciet

y ‘B

urea

u V

erita

s M

arin

e &

Offs

hore

SA

S’

, a

com

pany

org

aniz

ed a

nd e

xist

ing

unde

r th

e la

ws

of

Fra

nce,

re

gist

ered

in

N

ante

rre

unde

r th

e nu

mbe

r 82

1 13

1 84

4,

or a

ny o

ther

leg

al e

ntity

of

Bur

eau

Ver

itas

Gro

up a

s m

ay b

e sp

ecifi

ed in

the

rele

vant

con

trac

t, an

d w

hose

mai

n ac

tiviti

es

are

Cla

ssifi

catio

n an

d C

ertif

icat

ion

of s

hips

or

offs

hore

uni

ts.

2.14

“U

nit”

mea

ns a

ny s

hip

or v

esse

l or

offs

hore

uni

t or

str

uctu

re

of a

ny t

ype

or p

art

of it

or

syst

em w

heth

er li

nked

to

shor

e, r

iver

bed

or

sea

bed

or

not,

whe

ther

ope

rate

d or

loc

ated

at

sea

or i

n in

land

w

ater

s or

par

tly o

n la

nd,

incl

udin

g su

bmar

ines

, ho

verc

rafts

, dr

illin

g ri

gs,

offs

hore

ins

talla

tions

of

any

type

and

of

any

purp

ose,

the

ir re

late

d an

d an

cilla

ry e

quip

men

t, su

bsea

or

not,

such

as

wel

l he

ad

and

pipe

lines

, m

oori

ng l

egs

and

moo

ring

poi

nts

or o

ther

wis

e as

de

cide

d by

the

Soc

iety

. 3.

SC

OP

E A

ND

PE

RF

OR

MA

NC

E

3.1

The

Soc

iety

sha

ll pe

rfor

m t

he S

ervi

ces

acco

rdin

g to

the

app

li-ca

ble

natio

nal

and

inte

rnat

iona

l st

anda

rds

and

Indu

stry

Pra

ctic

e an

d al

way

s on

the

ass

umpt

ion

that

the

Clie

nt i

s aw

are

of s

uch

stan

dard

s an

d In

dust

ry P

ract

ice.

3.

2 S

ubje

ct to

the

Ser

vice

s pe

rfor

man

ce a

nd a

lway

s by

ref

eren

ce to

th

e R

ules

, the

Soc

iety

sha

ll:

• re

view

the

con

stru

ctio

n ar

rang

emen

ts o

f th

e U

nit

as s

how

n on

th

e do

cum

ents

pro

vide

d by

the

Clie

nt;

• co

nduc

t the

Uni

t sur

veys

at t

he p

lace

of t

he U

nit c

onst

ruct

ion;

•

clas

s th

e U

nit

and

ente

rs t

he U

nit’s

cla

ss in

the

Soc

iety

’s R

egis

-te

r;

• su

rvey

the

Uni

t pe

riodi

cally

in

serv

ice

to n

ote

that

the

req

uire

-m

ents

for

the

mai

nten

ance

of

clas

s ar

e m

et.

The

Clie

nt s

hall

info

rm t

he S

ocie

ty w

ithou

t del

ay o

f any

circ

umst

ance

s w

hich

may

ca

use

any

chan

ges

on th

e co

nduc

ted

surv

eys

or S

ervi

ces.

T

he S

ocie

ty w

ill n

ot:

• de

clar

e th

e ac

cept

ance

or

co

mm

issi

onin

g of

a

Uni

t, no

r its

co

nstr

uctio

n in

con

form

ity w

ith i

ts d

esig

n, s

uch

activ

ities

rem

ain-

ing

unde

r th

e ex

clus

ive

resp

onsi

bilit

y of

th

e U

nit’s

ow

ner

or

build

er;

• en

gage

in

any

wor

k re

latin

g to

the

des

ign,

con

stru

ctio

n, p

rodu

c-tio

n or

rep

air

chec

ks,

neith

er i

n th

e op

erat

ion

of t

he U

nit

or t

he

Uni

t’s t

rade

, ne

ither

in a

ny a

dvis

ory

serv

ices

, and

can

not

be h

eld

liabl

e on

thos

e ac

coun

ts.

4.

RE

SE

RV

AT

ION

CLA

US

E

4.1

The

Clie

nt s

hall

alw

ays:

(i)

mai

ntai

n th

e U

nit

in g

ood

cond

ition

af

ter

surv

eys;

(ii)

pre

sent

the

Uni

t afte

r su

rvey

s; (

iii)

pres

ent

the

Uni

t fo

r su

rvey

s;

and

(iv)

info

rm

the

Soc

iety

in

du

e co

urse

of

an

y ci

rcum

stan

ces

that

may

affe

ct t

he g

iven

app

rais

emen

t of

the

Uni

t or

caus

e to

mod

ify th

e sc

ope

of th

e S

ervi

ces.

4.

2 C

ertif

icat

es r

efer

ring

to t

he S

ocie

ty’s

Rul

es a

re o

nly

valid

if

issu

ed b

y th

e S

ocie

ty.

4.3

The

Soc

iety

has

ent

ire c

ontr

ol o

ver

the

Cer

tific

ates

iss

ued

and

may

at

an

y tim

e w

ithdr

aw

a C

ertif

icat

e at

its

en

tire

disc

retio

n in

clud

ing,

but

not

lim

ited

to,

in t

he f

ollo

win

g si

tuat

ions

: w

here

the

C

lient

fai

ls t

o co

mpl

y in

due

tim

e w

ith i

nstr

uctio

ns o

f th

e S

ocie

ty o

r w

here

the

Clie

nt f

ails

to

pay

in a

ccor

danc

e w

ith c

laus

e 6.

2 he

reun

-de

r.

5.

AC

CE

SS

AN

D S

AF

ET

Y

5.1

The

Clie

nt s

hall

give

to

the

Soc

iety

all

acce

ss a

nd i

nfor

mat

ion

nece

ssar

y fo

r th

e ef

ficie

nt p

erfo

rman

ce o

f th

e re

ques

ted

Ser

vice

s.

The

C

lient

sh

all

be

the

sole

re

spon

sibl

e fo

r th

e co

nditi

ons

of

pres

enta

tion

of t

he U

nit

for

test

s, t

rials

and

sur

veys

and

the

con

di-

tions

und

er w

hich

tes

ts a

nd t

rials

are

car

ried

out.

Any

inf

orm

atio

n,

draw

ings

, et

c. r

equi

red

for

the

perf

orm

ance

of

the

Ser

vice

s m

ust

be

mad

e av

aila

ble

in d

ue ti

me.

5.

2 T

he C

lient

sha

ll no

tify

the

Soc

iety

of

any

rele

vant

saf

ety

issu

e an

d sh

all

take

all

nece

ssar

y sa

fety

-rel

ated

mea

sure

s to

ens

ure

a sa

fe w

ork

envi

ronm

ent

for

the

Soc

iety

or

any

of it

s of

ficer

s, e

mpl

oy-

ees,

ser

vant

s, a

gent

s or

sub

cont

ract

ors

and

shal

l co

mpl

y w

ith a

ll ap

plic

able

saf

ety

regu

latio

ns.

6. P

AY

ME

NT

OF

INV

OIC

ES

6.

1 T

he p

rovi

sion

of

the

Ser

vice

s by

the

Soc

iety

, w

heth

er c

ompl

ete

or n

ot,

invo

lve,

for

the

par

t ca

rrie

d ou

t, th

e pa

ymen

t of

fee

s th

irty

(30)

day

s up

on is

suan

ce o

f the

invo

ice.

6.

2 W

ithou

t pr

ejud

ice

to a

ny o

ther

rig

hts

here

unde

r, i

n ca

se o

f C

lient

’s p

aym

ent

defa

ult,

the

Soc

iety

sha

ll be

ent

itled

to

char

ge,

in

addi

tion

to t

he a

mou

nt n

ot p

rope

rly

paid

, i

nter

ests

equ

al t

o tw

elve

(1

2) m

onth

s LI

BO

R p

lus

two

(2)

per

cent

as

of d

ue d

ate

calc

ulat

ed

on t

he n

umbe

r of

day

s su

ch p

aym

ent

is d

elin

quen

t. T

he S

ocie

ty

shal

l al

so h

ave

the

right

to

with

hold

cer

tific

ates

and

oth

er d

ocu-

men

ts a

nd/o

r to

sus

pend

or

revo

ke th

e va

lidity

of c

ertif

icat

es.

6.3

In c

ase

of d

ispu

te o

n th

e in

voic

e am

ount

, the

und

ispu

ted

port

ion

of t

he in

voic

e sh

all

be p

aid

and

an e

xpla

natio

n on

the

dis

pute

sha

ll ac

com

pany

pa

ymen

t so

th

at

actio

n ca

n be

ta

ken

to

solv

e th

e di

sput

e.

7.

LIA

BIL

ITY

7.

1 T

he S

ocie

ty b

ears

no

liabi

lity

for

cons

eque

ntia

l lo

ss.

For

the

pu

rpos

e of

th

is

clau

se

cons

eque

ntia

l lo

ss s

hall

incl

ude,

w

ithou

t lim

itatio

n:

• In

dire

ct o

r co

nseq

uent

ial l

oss;

•

Any

los

s an

d/or

def

erra

l of

pro

duct

ion,

los

s of

pro

duct

, lo

ss o

f us

e, lo

ss o

f ba

rgai

n, lo

ss o

f re

venu

e, lo

ss o

f pr

ofit

or a

ntic

ipat

ed

prof

it, l

oss

of b

usin

ess

and

busi

ness

int

erru

ptio

n, i

n ea

ch c

ase

whe

ther

dire

ct o

r in

dire

ct.

The

Clie

nt s

hall

save

, in

dem

nify

, de

fend

and

hol

d ha

rmle

ss t

he

Soc

iety

fr

om

the

Clie

nt’s

ow

n co

nseq

uent

ial

loss

re

gard

less

of

ca

use.

7.

2 In

any

cas

e, t

he S

ocie

ty’s

max

imu

m l

iabi

lity

tow

ards

the

Clie

nt

is li

mite

d to

one

hun

dred

and

fifty

per

-cen

ts (

150%

) of

the

pric

e pa

id

by t

he C

lient

to

the

Soc

iety

for

the

per

form

ance

of

the

Ser

vice

s.

Thi

s lim

it ap

plie

s re

gard

less

of f

ault

by th

e S

ocie

ty, i

nclu

ding

bre

ach

of c

ontr

act,

brea

ch o

f war

rant

y, to

rt, s

tric

t lia

bilit

y, b

reac

h of

sta

tute

. 7.

3 A

ll cl

aim

s sh

all

be p

rese

nted

to

the

Soc

iety

in

wri

ting

with

in

thre

e (3

) m

onth

s of

the

Ser

vice

s’ p

erfo

rman

ce o

r (if

lat

er)

the

date

w

hen

the

even

ts w

hich

are

rel

ied

on w

ere

first

dis

cove

red

by t

he

Clie

nt.

Any

cl

aim

no

t so

pr

esen

ted

as

defin

ed

abov

e sh

all

be

deem

ed w

aive

d an

d ab

solu

tely

tim

e ba

rred

.

8. IN

DE

MN

ITY

CLA

US

E

8.1

The

Clie

nt a

gree

s to

rel

ease

, in

dem

nify

and

hol

d ha

rmle

ss t

he

Soc

iety

fro

m a

nd a

gain

st a

ny a

nd a

ll cl

aim

s, d

em

ands

, la

wsu

its o

r ac

tions

fo

r da

mag

es,

incl

udin

g le

gal

fees

, fo

r ha

rm

or

loss

to

pe

rson

s an

d/or

pro

pert

y ta

ngib

le, i

ntan

gibl

e or

oth

erw

ise

whi

ch m

ay

be b

roug

ht a

gain

st t

he S

ocie

ty,

inci

dent

al t

o, a

risin

g ou

t of

or

in

conn

ectio

n w

ith t

he p

erfo

rman

ce o

f th

e S

ervi

ces

exce

pt f

or t

hose

cl

aim

s ca

used

so

lely

an

d co

mpl

etel

y by

th

e ne

glig

ence

of

th

e S

ocie

ty, i

ts o

ffice

rs, e

mpl

oyee

s, s

erva

nts,

age

nts

or s

ubco

ntra

ctor

s.

9.

TE

RM

INA

TIO

N

9.1

The

Par

ties

shal

l ha

ve t

he r

ight

to

term

inat

e th

e S

ervi

ces

(and

th

e re

leva

nt c

ontr

act)

for

con

veni

ence

afte

r gi

ving

the

oth

er P

arty

th

irty

(30)

day

s’ w

ritte

n no

tice,

and

with

out

prej

udic

e to

cla

use

6 ab

ove.

9.

2 In

suc

h a

case

, th

e cl

ass

gran

ted

to t

he c

once

rned

Uni

t an

d th

e pr

evio

usly

iss

ued

cert

ifica

tes

shal

l re

mai

n va

lid u

ntil

the

date

of

effe

ct o

f th

e te

rmin

atio

n no

tice

issu

ed,

subj

ect

to c

ompl

ianc

e w

ith

clau

se 4

.1 a

nd 6

abo

ve.

10

. FO

RC

E M

AJE

UR

E

10.1

Nei

ther

Par

ty s

hall

be r

espo

nsib

le f

or a

ny f

ailu

re t

o fu

lfil

any

term

or

prov

isio

n of

the

Con

ditio

ns if

and

to th

e ex

tent

that

fulfi

lmen

t ha

s be

en d

elay

ed o

r te

mpo

raril

y pr

even

ted

by a

for

ce m

ajeu

re

occu

rren

ce w

ithou

t th

e fa

ult

or n

eglig

ence

of

the

Par

ty a

ffect

ed a

nd

whi

ch,

by t

he e

xerc

ise

of r

easo

nabl

e di

ligen

ce,

the

said

Par

ty i

s un

able

to p

rovi

de a

gain

st.

10.2

For

the

pur

pose

of

this

cla

use,

for

ce m

ajeu

re s

hall

mea

n an

y ci

rcum

stan

ce n

ot b

eing

with

in a

Par

ty’s

rea

sona

ble

cont

rol

incl

ud-

ing,

but

not

lim

ited

to:

acts

of

God

, na

tura

l di

sast

ers,

epi

dem

ics

or

pand

emic

s, w

ars,

ter

rori

st a

ttack

s, r

iots

, sa

bota

ges,

im

posi

tions

of

sanc

tions

, em

barg

oes,

nuc

lear

, ch

emic

al o

r bi

olog

ical

con

tam

ina-

tions

, la

ws

or a

ctio

n ta

ken

by a

gov

ernm

ent

or

publ

ic a

utho

rity,

qu

otas

or

proh

ibiti

on,

expr

opria

tions

, de

stru

ctio

ns o

f th

e w

orks

ite,

expl

osio

ns,

fires

, ac

cide

nts,

any

labo

ur o

r tr

ade

disp

utes

, st

rikes

or

lock

outs

11. C

ON

FID

EN

TIA

LIT

Y

11.1

The

doc

umen

ts a

nd d

ata

prov

ided

to

or p

repa

red

by t

he S

ocie

ty in

pe

rfor

min

g th

e S

ervi

ces,

and

the

info

rmat

ion

mad

e

avai

labl

e to

the

Soc

iety

, ar

e tr

eate

d as

con

fiden

tial

exce

pt w

here

the

in

form

atio

n:

• is

alre

ady

know

n by

the

rec

eivi

ng P

arty

fro

m a

noth

er s

ourc

e an

d is

pr

oper

ly a

nd l

awfu

lly i

n th

e po

sses

sion

of

the

rece

ivin

g P

arty

prio

r to

th

e da

te th

at it

is d

iscl

osed

; •

is

alre

ady

in

poss

essi

on

of

the

publ

ic

or

has

ente

red

the

publ

ic

dom

ain,

oth

erw

ise

than

thro

ugh

a br

each

of t

his

oblig

atio

n;

• is

ac

quir

ed i

ndep

ende

ntly

fr

om

a th

ird

part

y th

at

has

the

right

to

di

ssem

inat

e su

ch in

form

atio

n;

• is

req

uire

d to

be

disc

lose

d un

der

appl

icab

le la

w o

r by

a g

over

nmen

tal

orde

r, d

ecre

e, r

egul

atio

n or

rul

e or

by

a st

ock

exch

ange

aut

horit

y (p

rovi

ded

that

the

rec

eivi

ng P

arty

sha

ll m

ake

all

reas

onab

le e

ffort

s to

gi

ve p

rom

pt w

ritte

n no

tice

to t

he d

iscl

osin

g P

arty

prio

r to

suc

h di

sclo

-su

re.

11.2

The

Soc

iety

and

the

Clie

nt s

hall

use

the

conf

iden

tial

info

rmat

ion

excl

usiv

ely

with

in t

he f

ram

ew

ork

of t

heir

activ

ity u

nder

lyin

g th

ese

Con

di-

tions

. 11

.3 C

onfid

entia

l in

form

atio

n sh

all

only

be

prov

ided

to

third

par

ties

with

th

e pr

ior

wri

tten

cons

ent

of t

he o

ther

Par

ty.

How

ever

, su

ch p

rior

cons

ent

shal

l no

t be

req

uire

d w

hen

the

Soc

iety

pro

vide

s th

e co

nfid

entia

l in

for-

mat

ion

to a

sub

sidi

ary.

11

.4 T

he S

ocie

ty s

hall

have

the

rig

ht t

o di

sclo

se t

he c

onfid

entia

l in

for-

mat

ion

if re

quire

d to

do

so u

nder

reg

ulat

ions

of

the

Inte

rnat

iona

l Ass

ocia

-tio

n of

Cla

ssifi

catio

ns S

ocie

ties

(IA

CS

) or

any

sta

tuto

ry o

blig

atio

ns.

12. I

NT

ELL

EC

TU

AL

PR

OP

ER

TY

12

.1 E

ach

Par

ty e

xclu

sive

ly o

wns

all

right

s to

its

Int

elle

ctua

l P

rope

rty

crea

ted

befo

re o

r af

ter

the

com

men

cem

ent

date

of

the

Con

ditio

ns a

nd

whe

ther

or

not a

ssoc

iate

d w

ith a

ny c

ontr

act b

etw

een

the

Par

ties.

12

.2

The

In

telle

ctua

l P

rope

rty

deve

lope

d fo

r th

e pe

rfor

man

ce

of

the

Ser

vice

s in

clud

ing,

but

not

lim

ited

to d

raw

ings

, ca

lcul

atio

ns,

and

repo

rts

shal

l rem

ain

excl

usiv

e pr

oper

ty o

f the

Soc

iety

.

13. A

SS

IGN

ME

NT

13

.1 T

he c

ontr

act

resu

lting

fro

m t

o th

ese

Con

ditio

ns c

anno

t be

ass

igne

d or

tra

nsfe

rred

by

any

mea

ns b

y a

Par

ty t

o a

third

par

ty w

ithou

t th

e pr

ior

wri

tten

cons

ent o

f the

oth

er P

arty

. 1

3.2

The

Soc

iety

sha

ll ho

wev

er h

ave

the

right

to

assi

gn o

r tr

ansf

er b

y an

y m

eans

the

said

con

trac

t to

a su

bsid

iary

of t

he B

urea

u V

erita

s G

roup

.

14. S

EV

ER

AB

ILIT

Y

14.1

Inv

alid

ity o

f on

e or

mor

e pr

ovis

ions

doe

s no

t af

fect

the

rem

aini

ng

prov

isio

ns.

14.2

Def

initi

ons

here

in t

ake

prec

eden

ce o

ver

othe

r de

finiti

ons

whi

ch m

ay

appe

ar in

oth

er d

ocum

ents

issu

ed b

y th

e S

ocie

ty.

14.3

In

case

of

doub

t as

to

the

inte

rpre

tatio

n of

the

Con

ditio

ns,

the

Eng

lish

text

sha

ll pr

evai

l.

15

. GO

VE

RN

ING

LA

W A

ND

DIS

PU

TE

RE

SO

LUT

ION

15

.1 T

he C

ondi

tions

sha

ll be

con

stru

ed a

nd g

over

ned

by t

he l

aws

of

Eng

land

and

Wal

es.

15.2

The

Soc

iety

and

the

Clie

nt s

hall

mak

e ev

ery

effo

rt t

o se

ttle

any

disp

ute

amic

ably

and

in g

ood

faith

by

way

of

nego

tiatio

n w

ithin

thi

rty

(30)

da

ys f

rom

the

dat

e of

rec

eipt

by

eith

er o

ne o

f th

e P

artie

s of

a w

ritte

n no

tice

of s

uch

a di

sput

e.

15.3

Fai

ling

that

, th

e di

sput

e sh

all

final

ly b

e se

ttled

by

arbi

trat

ion

unde

r th

e LC

IA r

ules

, w

hich

rul

es a

re d

eem

ed t

o b

e in

corp

orat

ed b

y re

fere

nce

into

this

cla

use.

The

num

ber

of a

rbitr

ator

s sh

all b

e th

ree

(3).

The

pla

ce o

f ar

bitr

atio

n sh

all b

e Lo

ndon

(U

K).

16. P

RO

FE

SS

ION

NA

L E

TH

ICS

16

.1 E

ach

Par

ty s

hall

cond

uct

all

activ

ities

in

com

plia

nce

with

all

law

s,

stat

utes

, ru

les,

and

reg

ulat

ions

app

licab

le t

o su

ch P

arty

incl

udin

g bu

t no

t lim

ited

to:

child

lab

our,

for

ced

labo

ur,

colle

ctiv

e ba

rgai

ning

, di

scrim

ina-

tion,

ab

use,

w

orki

ng

hour

s an

d m

inim

um

w

ages

, an

ti-br

iber

y,

anti-

corr

uptio

n. E

ach

of t

he P

artie

s w

arra

nts

that

nei

ther

it,

nor

its a

ffilia

tes,

ha

s m

ade

or w

ill m

ake,

with

res

pect

to

the

mat

ters

pro

vide

d fo

r he

reun

-de

r, a

ny o

ffer,

pay

men

t, gi

ft or

aut

horiz

atio

n of

the

pay

men

t of

any

m

oney

dir

ectly

or

indi

rect

ly,

to o

r fo

r th

e us

e or

ben

efit

of a

ny o

ffici

al o

r em

ploy

ee o

f the

gov

ernm

ent,

polit

ical

par

ty, o

ffici

al, o

r ca

ndid

ate.

16

.2 I

n ad

ditio

n, t

he C

lient

sha

ll ac

t co

nsis

tent

ly w

ith t

he S

ocie

ty’s

Cod

e of

Eth

ics

of B

urea

u V

erita

s. h

ttp://

ww

w.b

urea

uver

itas.

com

/hom

e/ab

out-

us/e

thic

s+an

d+co

mpl

ianc

e/

1. IN

DE

PE

ND

EN

CY

OF

TH

E S

OC

IET

Y A

ND

AP

PLI

CA

BLE

TE

RM

S

1.1

The

Soc

iety

sha

ll re

mai

n at

all

times

an

inde

pend

ent

cont

ract

or

and

neith

er t

he S

ocie

ty n

or a

ny o

f its

offi

cers

, e

mpl

oyee

s, s

erva

nts,

ag

ents

or

subc

ontr

acto

rs s

hall

be o

r ac

t as

an

empl

oyee

, se

rvan

t or

ag

ent o

f any

oth

er p

arty

her

eto

in th

e pe

rfor

man

ce o

f the

Ser

vice

s.

1.2

The

op

erat

ions

of

th

e S

ocie

ty

in

prov

idin

g its

S

ervi

ces

are

excl

usiv

ely

cond

ucte

d by

way

of

rand

om i

nspe

ctio

ns a

nd d

o no

t, in

an

y ci

rcum

stan

ces,

invo

lve

mon

itorin

g or

exh

aust

ive

verif

icat

ion.

1.

3 T

he S

ocie

ty a

cts

as a

ser

vice

s pr

ovid

er. T

his

cann

ot b

e co

nstr

ued

as a

n ob

ligat

ion

bear

ing

on t

he S

ocie

ty t

o ob

tain

a r

esul

t or

as

a w

arra

nty.

T

he

Soc

iety

is

no

t an

d m

ay

not

be

cons

ider

ed

as

an

unde

rwri

ter,

br

oker

in

U

nit’s

sa

le

or

char

terin

g,

expe

rt

in

Uni

t’s

valu

atio

n, c

onsu

lting

eng

inee

r, c

ontr

olle

r, n

aval

arc

hite

ct,

man

ufac

-tu

rer,

shi

pbui

lder

, re

pair

or

conv

ersi

on y

ard,

cha

rter

er o

r sh

ipow

ner;

no

ne o

f th

em a

bove

list

ed b

eing

rel

ieve

d of

any

of

thei

r ex

pres

sed

or

impl

ied

oblig

atio

ns a

s a

resu

lt of

the

inte

rven

tions

of t

he S

ocie

ty.

1.4

The

Ser

vice

s ar

e ca

rrie

d ou

t by

the

Soc

iety

acc

ordi

ng t

o th

e ap

plic

able

Rul

es a

nd t

o th

e B

urea

u V

erita

s’ C

ode

of E

thic

s. T

he

Soc

iety

onl

y is

qua

lifie

d to

app

ly a

nd in

terp

ret i

ts R

ules

. 1.

5 T

he C

lient

ack

now

ledg

es th

e la

test

ver

sion

s of

the

Con

ditio

ns a

nd

of th

e ap

plic

able

Rul

es a

pply

ing

to th

e S

ervi

ces’

per

form

ance

. 1.

6 U

nles

s an

ex

pres

s w

ritte

n ag

reem

ent

is

mad

e be

twee

n th

e P

artie

s on

the

app

licab

le R

ules

, th

e ap

plic

able

Rul

es s

hall

be t

he

rule

s ap

plic

able

at

the

time

of t

he S

ervi

ces’

per

form

ance

and

con

-tr

act’s

exe

cutio

n.

1.7

The

Ser

vice

s’ p

erfo

rman

ce i

s so

lely

bas

ed o

n th

e C

ondi

tions

. N

o ot

her

term

s sh

all a

pply

whe

ther

exp

ress

or

impl

ied.

2. D

EF

INIT

ION

S

2.1

“Cer

tific

ate(

s)”

mea

ns c

lass

cer

tific

ates

, at

test

atio

ns a

nd r

epor

ts

follo

win

g th

e S

ocie

ty’s

int

erve

ntio

n. T

he C

ertif

icat

es a

re a

n ap

prai

se-

men

t gi

ven

by t

he S

ocie

ty t

o th

e C

lient

, at

a c

erta

in d

ate,

fol

low

ing

surv

eys

by i

ts s

urve

yors

on

the

leve

l of

com

plia

nce

of t

he U

nit

to t

he

Soc

iety

’s R

ules

or

to t

he d

ocum

ents

of

refe

renc

e fo

r th

e S

ervi

ces

prov

ided

. The

y ca

nnot

be

cons

true

d as

an

impl

ied

or e

xpre

ss w

arra

n-ty

of

safe

ty,

fitne

ss f

or t

he p

urpo

se,

seaw

orth

ines

s of

the

Uni

t or

of i

ts

valu

e fo

r sa

le, i

nsur

ance

or

char

terin

g.

2.2

“Cer

tific

atio

n” m

eans

the

act

ivity

of

cert

ifica

tion

in a

pplic

atio

n of

na

tiona

l an

d in

tern

atio

nal

regu

latio

ns o

r st

anda

rds,

in

part

icul

ar b

y de

lega

tion

from

diff

eren

t go

vern

men

ts t

hat

can

resu

lt in

the

iss

uanc

e of

a c

ertif

icat

e.

2.3

“Cla

ssifi

catio

n” m

eans

the

cla

ssifi

catio

n of

a U

nit

that

can

res

ult

or n

ot i

n th

e is

suan

ce o

f a

clas

s ce

rtifi

cate

with

ref

eren

ce t

o th

e R

ules

. 2.

4 “C

lient

” m

eans

the

Par

ty a

nd/o

r its

rep

rese

ntat

ive

requ

estin

g th

e S

ervi

ces.

2.

5 “C

ondi

tions

” m

eans

the

ter

ms

and

cond

ition

s se

t ou

t in

the

pr

esen

t doc

umen

t. 2.

6 “In

dust

ry P

ract

ice”

mea

ns I

nter

natio

nal

Mar

itim

e an

d/or

Off-

shor

e in

dust

ry p

ract

ices

. 2.

7 “In

telle

ctua

l P

rope

rty”

m

eans

all

pate

nts,

rig

hts

to i

nven

tions

, ut

ility

mod

els,

cop

yrig

ht a

nd r

elat

ed r

ight

s, tr

ade

mar

ks, l

ogos

, ser

vice

m

arks

, tra

de d

ress

, bus

ines

s an

d do

mai

n na

mes

, ri

ghts

in tr

ade

dres

s or

get

-up,

rig

hts

in g

oodw

ill o

r to

sue

for

pas

sing

off,

unf

air

com

peti-

tion

right

s, r

ight

s in

des

igns

, rig

hts

in c

ompu

ter

softw

are,

dat

abas

e ri

ghts

, to

pogr

aphy

rig

hts,

m

oral

rig

hts,

rig

hts

in

conf

iden

tial

info

r-m

atio

n (in

clud

ing

know

-how

and

tra

de s

ecre

ts),

met

hods

and

pro

to-

cols

for

Ser

vice

s, a

nd a

ny o

ther

int

elle

ctua

l pr

oper

ty r

ight

s, i

n ea

ch

case

whe

ther

cap

able

of

regi

stra

tion,

reg

iste

red

or u

nreg

iste

red

and

incl

udin

g al

l app

licat

ions

for

and

rene

wal

s, r

ever

sion

s or

ext

ensi

ons

of

such

rig

hts,

and

all

sim

ilar

or e

quiv

alen

t rig

hts

or f

orm

s of

pro

tect

ion

in a

ny p

art o

f the

wor

ld.

2.8

“Par

ties”

mea

ns th

e S

ocie

ty a

nd C

lient

toge

ther

. 2.

9 “P

arty

” m

eans

the

Soc

iety

or

the

Clie

nt.

2.10

“R

egis

ter”

m

eans

th

e re

gist

er

publ

ishe

d an

nual

ly

by

the

Soc

iety

. 2.

11 “

Rul

es”

mea

ns th

e S

ocie

ty’s

cla

ssifi

catio

n ru

les,

gui

danc

e no

tes

and

othe

r do

cum

ents

. T

he R

ules

, pr

oced

ures

and

ins

truc

tions

of

the

Soc

iety

tak

e in

to a

ccou

nt a

t th

e da

te o

f th

eir

prep

arat

ion

the

stat

e of

cu

rren

tly a

vaila

ble

and

prov

en t

echn

ical

min

imu

m r

equi

rem

ents

but

ar

e no

t a

stan

dard

or

a

code

of

co

nstr

uctio

n ne

ither

a

guid

e

fo

r m

aint

enan

ce,

a sa

fety

ha

ndbo

ok

or

a gu

ide

of

prof

essi

onal

pr

actic

es, a

ll of

whi

ch a

re a

ssum

ed to

be

know

n in

det

ail a

nd

Bur

eau

Ver

itas

Mar

ine

& O

ffsho

re G

ener

al C

ondi

tions

-

Edi

tion

Janu

ary

2017

RULE NOTE NR 527

NR 527Rules for the Classification of

Ships Operating in Polar Waters and Icebreakers

SECTION 1 GENERAL

SECTION 2 STRUCTURAL REQUIREMENTS FOR POLAR CLASS AND ICEBREAKER SHIPS

SECTION 3 MACHINERY REQUIREMENTS FOR POLAR CLASS AND ICEBREAKER SHIPS

SECTION 4 SHIPS OPERATING IN POLAR WATERS (POLAR CAT)

APPENDIX 1 POLAR WATER OPERATIONAL MANUAL (PWOM)

APPENDIX 2 METHOD FOR DETERMINING EQUIVALENT ICE CLASS

January 2017

Unless otherwise specified, these rules apply to ships for which contracts aresigned after January, 1st 2017. The Society may refer to the contents hereofbefore January, 1st 2017, as and when deemed necessary or appropriate.

2 Bureau Veritas January 2017

Section 1 General

1 General 7

1.1 Application1.2 Additional requirement1.3 Ice waterlines1.4 Bow form1.5 Shallow water1.6 Output of propulsion machinery

2 Additional class notations POLAR CLASS 9

2.1 Scope

3 Service notations Icebreaker 9

3.1 Scope

4 Additional service features POLAR CAT 10

4.1 Scope

Section 2 Structural Requirements for Polar Class and Icebreaker ships

1 General 13

1.1 Hull areas1.2 Hull shape1.3 Direct structural calculations

2 Materials and welding 15

2.1 Material classes and grades2.2 Welding

3 Corrosion/abrasion additions and steel renewal 17

3.1 Corrosion/abrasion additions3.2 Steel renewal

4 Design ice loads 17

4.1 General4.2 Glancing impact load characteristics - Class factors4.3 Bow area4.4 Hull areas other than the bow area4.5 Pressure within the design load patch4.6 Hull area factor

5 Longitudinal strength 21

5.1 Application5.2 Hull girder ice loads5.3 Normal stress5.4 Shear stress5.5 Buckling

6 Shell plating 23

6.1 General6.2 Net thickness

January 2017 Bureau Veritas 3

7 Framing scantlings 24

7.1 General7.2 Actual net effective shear area of ordinary stiffeners7.3 Actual net effective plastic section modulus of ordinary stiffeners7.4 Structural stability7.5 Ordinary stiffeners in bottom structures and transverse ordinary stiffeners in side

structures7.6 Longitudinal ordinary stiffeners in side structures7.7 Oblique ordinary stiffeners7.8 Web frames and load-carrying stringers

8 Plated structures 28

8.1 General

9 Stem and stern arrangement 28

9.1 Fore part9.2 Aft part

10 Hull outfittings 29

10.1 Rudders10.2 Arrangements for towing

Section 3 Machinery Requirements for Polar Class and Icebreaker ships

1 General 30

1.1 Application1.2 Drawings and particulars to be submitted1.3 Principle of design review for main propulsion and machinery1.4 System design

2 Materials 31

2.1 Materials exposed to sea water2.2 Materials exposed to sea water temperature2.3 Material exposed to low air temperature

3 Ice interaction load 31

3.1 Ice class factors3.2 Propeller ice interaction3.3 Design ice loads for open propeller3.4 Design ice loads for ducted propeller3.5 Design loads on propulsion line

4 Design 37

4.1 Design principle4.2 Azimuth main propulsors4.3 Blade design4.4 Prime movers

5 Machinery fastening loading accelerations 37

5.1 General5.2 Accelerations

6 Auxiliary systems 38

6.1 General


7 Sea inlets and cooling water systems 38

7.1 General

8 Ballast tanks 38

8.1 General

9 Ventilation system 38

9.1 General

10 Alternative design 38

10.1 General

Section 4 Ships Operating in Polar Waters (POLAR CAT)

1 General 39

1.1 Application1.2 Definitions1.3 Documents to be submitted

2 Operational assessment 40

2.1 General2.2 Methodology

3 Safety 41

3.1 Polar Water Operational Manual (PWOM)3.2 Ship structure3.3 Stability3.4 Watertight and weathertight integrity3.5 Machinery installations3.6 Fire safety and protection3.7 Life-saving appliances3.8 Safety of navigation3.9 Communication

4 Pollution prevention 45

4.1 Pollution by oil4.2 Pollution by sewage

Appendix 1 Polar Water Operational Manual (PWOM)

1 General 47

1.1 Application1.2 Table of contents

Appendix 2 Method for Determining Equivalent Ice Class

1 General 50

1.1 Application1.2 Principles1.3 Process of assessment


NR 527, Sec 1

SECTION 1 GENERAL

1 General

1.1 Application

1.1.1 This Rule Note applies to ships constructed of steeland intended for navigation in ice-infested polar waters,including icebreakers. This Rule Note gives the require-ments for the assignment of:

• one of the additional class notations POLAR CLASS

• one of the service notations Icebreaker

• one of the additional service features POLAR CAT

The requirements of this Rule Note apply in addition to theapplicable requirements of NR467 Rules for the Classifica-tion of Steel Ships (hereinafter referred to as the Rules forSteel Ships).

1.1.2 Selection of an additional class notation POLAR CLASS or a service notation Icebreaker

It is the responsibility of the Owner to select an appropriateadditional class notation POLAR CLASS or an appropriate

service notation Icebreaker. The ice descriptions given inTab 2 and Tab 3 are intended to guide Owners, Designersand Administrations in selecting an appropriate additionalclass notation POLAR CLASS or an appropriate servicenotation Icebreaker to match the requirements for the shipswith its intended voyages or services.

Note 1: Complementary information may be found in NI543 IceReinforcement Selection in Different World Navigation Areas con-cerning the choice of the appropriate notation in function of thearea of navigation and the period of the year.

1.1.3 Selection of an additional service feature POLAR CAT

For ships intended for navigation in polar waters, one of thefollowing additional service features, as defined in [4], is tobe assigned and selected according to the ship categories ofthe IMO International Code for Ships Operating in PolarWaters (Polar Code):

• POLAR CAT-A for category A ship

• POLAR CAT-B for category B ship

• POLAR CAT-C for category C ship.

Figure 1 : Antarctic area


NR 527, Sec 1

Figure 2 : Arctic waters

Polar waters means Arctic waters and/or the Antarctic area.Fig 1 and Fig 2 are given for illustrative purposes only.

Antarctic area means the sea area south of latitude 60° S.

Arctic waters means those waters which are located

a) north of a line from the latitude 58º00’.0 N and longi-tude 042º00’.0 W

b) to latitude 64º37’.0 N, longitude 035º27’.0 W

c) and thence by a rhumb line to latitude 67º03’.9 N, longi-tude 026º3’.4 W

d) and thence by a rhumb line to the latitude 70º49’.56 Nand longitude 008º59’.61 W (Sørkapp, Jan Mayen)

e) and by the southern shore of Jan Mayen to 73º31’.6 Nand 019º01’.0 E by the Island of Bjørnøya,

f) and thence by a great circle line to the latitude68º38’.29 N and longitude 043º23’.08 E (Cap KaninNos)

g) and hence by the northern shore of the Asian Continenteastward to the Bering Strait

h) and thence from the Bering Strait westward to latitude60º N as far as Il’pyrskiy

i) and following the 60th North parallel eastward as far asand including Etolin Strait

j) and thence by the northern shore of the North Ameri-can continent as far south as latitude 60º N

k) and thence eastward along parallel of latitude 60º N, tolongitude 056º37’.1 W

l) and thence to the latitude 58º00’.0 N, longitude042º00’.0 W.

1.1.4 Definition of Icebreaker“Icebreaker” refers to any ship having an operational profilethat includes escort or ice management functions, havingpowering and dimensions that allow it to undertake aggres-sive operations in ice-covered waters.

1.1.5 According to the notation, the functions of the shipand its equipment, the following Sections apply:• Sec 2: structural requirements for additional class nota-

tions POLAR CLASS and service notations Icebreaker• Sec 3: machinery requirements for additional class nota-

tions POLAR CLASS and service notations Icebreaker• Sec 4: requirements for additional service features

POLAR CAT.

1.1.6 RestrictionsIf hull and machinery are constructed such as to complywith the requirements of different additional class notationsPOLAR CLASS, then both the hull and the machinery are tobe assigned the lower of these additional class notations inthe Certificate of Classification. Compliance of hull ormachinery with the requirements of a higher additionalclass notation POLAR CLASS is also to be indicated in theAnnex to the Certificate of Classification.

The same principle applies to ships having a service nota-tion Icebreaker.


NR 527, Sec 1

1.2 Additional requirement

1.2.1 Ships with additional class notation POLAR CLASS or service notation Icebreaker

Ships complying with the requirements of this Rule Note inorder to be assigned one of the additional class notationsPOLAR CLASS or one of the service notations Icebreakerare also to comply with the requirements for the assignmentof the additional class notation COLD (H tDH , E tDE) (seePt E, Ch 10, Sec 11 of the Rules for Steel Ships).Note 1: Ships with the additional class notation POLAR CLASS 6or POLAR CLASS 7 and not intended to operate in low air tempera-ture may be exempted of the additional class notation COLD(H tDH , E tDE).

1.2.2 Ships with additional service feature POLAR CAT

Ships complying with the requirements of this Rule Note inorder to be assigned one of the additional service featurePOLAR CAT and intended to operate in low air tempera-ture, as defined in Sec 4, [1.2.1], are also to comply withthe requirements for the assignment of the additional classnotation COLD (H tDH , E tDE), where the temperatures tDH

and tDE are as defined in Sec 4, [1.2.4]. The requirements forthe additional class notation COLD (H tDH , E tDE) are givenin Pt E, Ch 10, Sec 11 of the Rules for Steel Ships.

1.3 Ice waterlines

1.3.1 Upper ice waterlineThe upper ice waterline (UIWL) is defined by the maximumdraughts fore, amidships and aft, in ice navigation.

1.3.2 Lower ice waterlineThe lower ice waterline (LIWL) is defined by the minimumdraughts fore, amidships and aft, in ice navigation.

The lower ice waterline is to be determined with due regardto the ship’s ice-going capability in the ballast loading con-ditions. The propeller is to be fully submerged at the lowerice waterline.

1.3.3 Information to be submittedUIWL and LIWL upon which the design of the ship is basedare to be specified by the Designer in the plans submittedfor approval to the Society and are to be stated on the Cer-tificate of Classification.

1.4 Bow form

1.4.1 Bows with vertical sides and bulbous bows are to beavoided for ships having one of the additional class nota-tions POLAR CLASS 1 to POLAR CLASS 5.

For ships having the additional class notation POLARCLASS 6 or POLAR CLASS 7 and a bow with vertical sidesor a bulbous bow, the operational limitations are to beexplicitly stated on the Certificate of Classification (e.g.restricted from intentional ramming).

1.5 Shallow water

1.5.1 Shallow water may be considered as less than2 metres keel clearance.

1.6 Output of propulsion machinery

1.6.1 Scope

The minimum engine output requirement given in [1.6.2] isonly applicable to ships having one of the service notationsIcebreaker.

1.6.2 Minimum propulsion machinery output

The design engine output, which is the maximum output thepropulsion machinery can continuously deliver to the pro-peller, is not to be less than the value given in Tab 1 for thecorresponding service notation.

Table 1 : Minimum engine output

2 Additional class notations POLAR CLASS

2.1 Scope

2.1.1 Ships having one of the additional class notationsPOLAR CLASS are to have the hull form and the propulsionpower such that the ship can operate independently or withicebreaker assistance, at continuous speed and up to the iceconditions described in Tab 2.

For ships not designed to operate independently in ice, suchoperational intent or limitations are to be explicitly statedon the Certificate of Classification.

Ramming is to be avoided for ships with one of the addi-tional class notations POLAR CLASS.

3 Service notations Icebreaker

3.1 Scope

3.1.1 Ships having one of the service notations Icebreakerare intended to sail without icebreaker assistance up to thecontinuous ice conditions described in Tab 3.

Ships with one of the service notations Icebreaker 1 to Ice-breaker 4 can perform unlimited ramming, provided thatthe maximum admissible speed in ice defined in Tab 3 isnot overcome.

Ships with one of the service notations Icebreaker 5 to Ice-breaker 7 can exceptionally perform ramming but this is notto be repeated if the ice does not fail at the first attempt.

Service notation Minimum engine output (kW)

Icebreaker 1 44000

Icebreaker 2 22000

Icebreaker 3 11000

Icebreaker 4 6000

Icebreaker 5Icebreaker 6Icebreaker 7

no minimum engine output

Note 1: For ships having the propulsion power determined bymodel tests or by full scale measurements, lower values of mini-mum engine output may be accepted, on a case-by-case basis.


NR 527, Sec 1

4 Additional service features POLAR CAT

4.1 Scope

4.1.1 The additional service features POLAR CAT aredefined as follows:

• POLAR CAT-A is assigned to ships designed for opera-tion in polar waters in at least medium first-year ice,which may include old ice inclusions

• POLAR CAT-B is assigned to ships designed for opera-tion in polar waters in at least thin first-year ice, whichmay include old ice inclusions, but in ice conditionsless severe than for POLAR CAT-A

• POLAR CAT-C is assigned to ships designed to operatein open water or ice conditions less severe than thoseincluded in POLAR CAT-A or POLAR CAT-B.

4.1.2 The allowed additional service features POLAR CATare given in Tab 4 with respect to the ice classes or the ser-vice notations Icebreaker assigned to the ships.

Table 2 : POLAR CLASS description

POLARCLASS

Icebreaker assisted operationsIndependent operations

In open ice (concentration < 6/10) (1) In close ice (concentration ≥ 6/10) (1)

Opera-tions

Ice description (2)

Max. ice thk (m)

Opera-tions

Ice description (2)

Max. ice thk (m)

Opera-tions

Ice description (2)

Max. ice thk (m)

1year-round

all multi-year ice

3,5year-round

all multi-year ice

3,5year-round

second-yearice which may include multi-year ice inclu-

sions

2,0

2year-round

moderatemulti-year ice

3,0year-round

moderatemulti-year ice

3,0year-round

thick first-year ice which may include old ice

inclusions

1,5

3year-round

second-yearice which may

include multi-year ice inclusions

2,5year-round

second-yearice which may

include multi-year ice inclusions

2,5year-round

medium first-year ice which

may include old ice inclusions

1,2

4year-round


inclusions

1,5year-round


inclusions

1,5year-round



1,0

5year-round



1,0year-round



1,0summer / autumn



0,8

6summer/ autumn



0,8summer / autumn



0,8summer / autumn

thinfirst-year ice

0,6

7summer/ autumn

thin first-year ice which may

include old ice inclusions

0,6summer / autumn

thin first-year ice which may

include old ice inclusions

0,6summer / autumn

thinfirst-year ice

0,4

(1) Portion of sea covered by the ice, expressed in tenths.(2) Based on World Meteorological Organization (WMO) Sea Ice Nomenclature.


NR 527, Sec 1

Table 3 : Icebreaker description

Table 4 : Additional service features POLAR CAT

Icebreaker

Independent operations in summer/autumn Independent operations in winter/spring Designramming speedin ice (knots)

Ice description (1)

Maximum ice thickness (m)

Ice description (1)

Maximum ice thickness (m)

1 without restrictions without restrictions multi-year ice 3,0 12,0

2 multi-year ice 3,0 second-year ice 2,5 9,0

3 second-year ice 2,5 thick first-year ice 1,8 7,0

4 thick first-year ice 1,8 medium first-year ice 1,2 5,5

5 medium first-year ice 1,2 medium first-year ice 1,0 5,5

6 medium first-year ice 1,0 medium first-year ice 0,8 4,5

7 medium first-year ice 0,8 thin first-year ice 0,6 4,5

(1) Based on World Meteorological Organization (WMO) Sea Ice Nomenclature.

Ice class or service notation POLAR CAT-A POLAR CAT-B POLAR CAT-C

POLAR CLASS 1, POLAR CLASS 2, POLAR CLASS 3, POLAR CLASS 4, POLAR CLASS 5Icebreaker 1, Icebreaker 2, Icebreaker 3, Icebreaker 4, Icebreaker 5

X − −

POLAR CLASS 6, POLAR CLASS 7Icebreaker 6, Icebreaker 7

− X −

ICE CLASS IA SUPER − X (1) X

ICE CLASS IA − X (1) X

Other or none − − X

Note 1: X : Allowed − : Not allowed.(1) The level of safety is to be demonstrated equivalent to the requirements of the standards acceptable for the ship category. This

equivalence can be determined using a method as described in App 2.


NR 527, Sec 2

SECTION 2 STRUCTURAL REQUIREMENTS FOR POLAR CLASS

AND ICEBREAKER SHIPS

Symbols

Lui : Rule length, in m, as defined in Pt B, Ch 1, Sec2, [3.1] of the Rules for Steel Ships but meas-ured at the upper ice waterline (UIWL)

FEui : Fore end, perpendicular to the upper ice water-line (UIWL) at the forward side of the stem

AEui : Aft end, perpendicular to the to the upper icewaterline (UIWL) at a distance Lui aft of the foreend

Bui : Ship moulded breadth, in m, at the upper icewaterline (UIWL)

Δui : Ship displacement at the upper ice waterline(UIWL), in t

x : Distance, in m, from the aft end (AEui) to thesection under consideration

b : bBow or bNonBow , in m, as appropriate for the areaunder consideration

bBow : Height of the design load patch, in m, in thebow area, defined in [4.3.8]

bNonBow : Height of the design load patch, in m, in hullareas other than the bow area, defined in[4.4.4]

bf : Flange width, in mm, of a stiffener (see Fig 9)

CAF : Hull area factor, defined in [4.6.1]

cARi : Load patch aspect ratio, defined in [4.3.4]

CC : Crushing failure class factor, defined in [4.2.1]

CD : Load patch dimensions class factor, defined in[4.2.1]

ci : Shape coefficient, defined in [4.3.3]

CF : Flexural failure class factor, defined in [4.2.1]

CL : Longitudinal strength class factor, defined in[4.2.1]

CΔ : Displacement class factor, defined in [4.2.1]

CPP, CPM, CPS: Peak pressure factors, defined in [4.5.2]

E : Young’s modulus, in N/mm2, to be taken equalto:

• E = 2,06 ⋅ 105 N/mm2 for steels in general

• E = 1,95 ⋅ 105 N/mm2 for stainless steels

• E = 7,00 ⋅ 104 N/mm2 for aluminium alloys

FBow : Total glancing impact force in the bow area, inkN, defined in [4.3.5]

FNonBow : Total glancing impact force in hull areas otherthan the bow area, in kN, defined in [4.4.1]

hw : Web height, in mm, of a stiffener (see Fig 9)

: Span, in m, of ordinary stiffeners

MSW,S : Design still water bending moment, in kN.m, insagging condition, defined in Pt B, Ch 5, Sec 2,[2.2] of the Rules for Steel Ships

pavg : Design ice load average pressure, in kN/m2,defined in [4.5.1]

pBow : Total glancing impact pressure in the bow area,in kN/m2, defined in [4.3.7]

qBow : Total glancing impact line load in the bow area,in kN/m, defined in [4.3.6]

qNonBow : Total glancing impact line load in hull areasother than the bow area, in kN/m, defined in[4.4.3]

QSW : Design still water shear force, in kN, defined inPt B, Ch 5, Sec 2, [2.3] of the Rules for SteelShips

ReH : Minimum yield stress of the material, in N/mm2

Rm : Ultimate minimum tensile strength of the mate-rial, in N/mm2, defined in Pt B, Ch 4, Sec 1,[2.1.1] of the Rules for Steel Ships

s : Spacing, in m, of ordinary stiffeners

tC : Corrosion/abrasion addition, in mm, defined in[3.1]

tf : Net flange thickness, in mm, of a stiffener (seeFig 9)

tnet : Net plate thickness required to resist ice loads,in mm, defined in [6.2]

tp : Net thickness, in mm, of attached plating of astiffener (see Fig 9)

tw : Net web thickness, in mm, of a stiffener (see Fig 9)

w : wBow or wNonBow , in m, as appropriate for thearea under consideration

wBow : Width of the design load patch, in m, in thebow area, defined in [4.3.8]

wNonBow : Width of the design load patch, in m, in hullareas other than the bow area, defined in[4.4.4]

α : Upper ice waterline angle, in degree (see Fig 4)

γ : Buttock angle at the upper ice waterline (angleof buttock line measured from horizontal), indegree (see Fig 4)

β : Frame angle, in degree, defined by:

tan β = tan α / tan γ (see Fig 4)

θ : Normal frame angle at the upper ice waterline,in m, defined by:

tan θ = tan β ⋅ cos α (see Fig 4).


NR 527, Sec 2

1 General

1.1 Hull areas

1.1.1 The hull of all ships having an additional class nota-tion POLAR CLASS or a service notation Icebreaker isdivided into areas reflecting the magnitude of the loads thatare expected to act upon them.

In the longitudinal direction, there are four regions: • Bow (B)• Bow Intermediate (BI)• Midbody (M)• Stern (S).

The Bow Intermediate, Midbody and Stern regions are fur-ther divided in the vertical direction into:• Bottom (b)

• Lower ()• Icebelt regions (i).

The extent of each hull area is indicated in Fig 1 for POLARCLASS ships, and in Fig 2 for Icebreaker ships, where hi ,measured at aft end of Bow region, in m, is given in Tab 1.

1.1.2 The upper ice waterline (UIWL) and the lower icewaterline (LIWL) are defined in Sec 1, [1.3].

Table 1 : Value of hi for hull area extents

1.1.3 The boundary between the Bow and Bow Intermedi-ate regions is to be located:

• afterward of the intersection point of the line of the stemand the ship baseline, and

• forward of 0,45 Lui aft of the fore end (FEui).

1.1.4 The boundary between the bottom and lower regionsis to be taken at the point where the shell is inclined 7° fromhorizontal.

1.1.5 If a ship is intended to operate astern in ice infestedpolar waters, the aft section of the ship is to be designedusing the Bow and Bow Intermediate hull area require-ments.

1.1.6 For ships having one of the service notations Ice-breaker, the forward boundary of the stern region is to be atleast 0,04Lui forward of the section where the parallel shipside at the upper ice waterline (UIWL) ends.

Figure 1 : Hull area extents for POLAR CLASS ships

POLAR CLASS or Icebreaker hi , in m

1 to 4 1,5

5 to 7 1,0

1,5 m

0,7b 0,15 Lui

UIWL

LIWL

0,04Lui aft of WL angle = 0 deg at UIWL

WL angle = 10 deg at UIWL

Si

S

Mi

M

Bli

BI

B 2,0 m

b = distance from AEui to maximumhalf breadth at UIWL

WL angle = 0 deg

WL angle = 10 deg

SbS Mb

M

Blb

Bl

BSi

UIWL

LIWL

MbM

Mi

hi

AEui

Midbody

FEui


NR 527, Sec 2

Figure 2 : Hull area extents for Icebreaker ships

Table 2 : Maximum value of angles γbow and αbow for the bow form

1.2 Hull shape

1.2.1 For ships having one of the additional class notationsPOLAR CLASS or one of the service notations Icebreaker,the maximum values of the angles γstem and αbow for the bowform (see Fig 3 with Bui evaluated at the midship section) aregiven as a guidance in Tab 2.

1.2.2 In addition, for ships having one of the service nota-tions Icebreaker 1 to Icebreaker 4, the normal frame angleθ (see Fig 4) to be fitted around the whole hull at the upperice waterline (UIWL) is to be greater than the values givenas a guidance in Tab 3.

1.3 Direct structural calculations

1.3.1 Direct structural calculations (beam or FE analysis)are not to be used as an alternative to the analytical proce-dures prescribed for the shell plating and the ordinary stiff-ener requirements given in this Section.

Figure 3 : Definition of angles γstem and αbow

POLAR CLASS or Icebreaker 1 2 3 4 5 6 7

Buttock angle at the stem γstem ,in degree 25 25 30 30 45 60 70

Waterline angle at the bow αbow, in degree 30 30 30 30 40 40 40

1.5 m

0.20 Lui

UIWL

LIWLSi

S

Mi

M

Bli

BI

B 2.0 m

SbS

Mb

M

Blb

Bl

B

Si

UIWL

LIWL

MbM

Mi

hi

Midbody

0.15 Lui 0.25 Lui

AEui FEui

Upper Ice Waterline

Upper Ice Waterline

Bui/4


NR 527, Sec 2

Figure 4 : Definition of hull angles

Table 3 : Minimum value of inclination of the hull (angle θ) at UIWL

1.3.2 When direct structural calculations are used to checkthe strength of primary supporting members (such as load-carrying stringers or web frames), the design ice loadsdefined in [4] are to be applied without being combinedwith any other loads.

1.3.3 The corresponding design load patch is to be appliedin accordance with [7.8.1].

2 Materials and welding

2.1 Material classes and grades

2.1.1 The material grade for hull structure is to be not lessthan those given in Tab 4 and Tab 5, based on the as-builtthickness of the material, the assigned additional class nota-tion POLAR CLASS or service notation Icebreaker, and thematerial classes of structural members given in Tab 6.

2.1.2 Material classes specified in Pt B, Ch 4, Sec 1, Tab 3of the Rules for Steel Ships are applicable to ships havingone of the additional class notations POLAR CLASS or oneof the services notations Icebreaker, regardless of the shiplength.In addition, material classes for weather and sea exposedstructural members and for members attached to theweather and sea exposed shell plating are given in Tab 6.

Where the material classes in Tab 6 and those in Pt B, Ch 4,Sec 1, Tab 3 of the Rules for Steel Ships differ, the highermaterial class is to be applied.

2.1.3 Material grades for all plating and attached framing ofhull structures and appendages situated below the level of0,3 m below the lower ice waterline (LIWL), as shown in Fig5, are to be obtained from Tab 4, based on the materialclasses for structural members in Tab 6, regardless of theadditional class notation POLAR CLASS or service notationIcebreaker assigned.

Table 4 : Material grade requirements for classes I, II and III

Icebreaker 1 to Icebreaker 4Position on the hull (x/Lui)

< 0,2 0,2 - 0,4 0,4 - 0,6 0,6 - 0,75 0,75 - 0,9 0,9 - 1,0

Normal frame angle θ, in degree 30 25 15 25 30 40

Longitudinal planWaterline plan

Section B-B

A

A

BB

Section A-A

As-built thickness t,in mm

Material class I Material class II Material class III

NSS HSS NSS HSS NSS HSS

t ≤ 15 A AH A AH AH AH

15 < t ≤ 20 A AH A AH B AH

20 < t ≤ 25 A AH B AH D DH

25 < t ≤ 30 A AH D DH D DH

30 < t ≤ 35 B AH D DH E EH

35 < t ≤ 40 B AH D DH E EH

40 < t ≤ 50 D DH E EH E EH

Note 1: “NSS” and “HSS” mean, respectively: “Normal Strength Steel” and “Higher Strength Steel”.


NR 527, Sec 2

Table 5 : Material grades for weather exposed plating

Table 6 : Material classes for structural members

Figure 5 : Steel grade requirements for submerged and weather exposed shell plating

2.1.4 Material grades for all weather exposed plating ofhull structures and appendages situated above the level of0,3 m below the lower ice waterline (LIWL), as shown in Fig5, are to be not less than those given in Tab 5.

2.1.5 Castings are to have specified properties consistent withthe expected service temperature for the cast component.

2.2 Welding

2.2.1 All weldings within ice-strengthened areas are to beof the double continuous type.

As-built thickness t,in mm

POLAR CLASS or Icebreaker

1 to 5 6 and 7 1 to 5 6 and 7 1 to 3 4 and 5 6 and 7

Material class I Material class II Material class III

NSS HSS NSS HSS NSS HSS NSS HSS NSS HSS NSS HSS NSS HSS

t ≤ 10 B AH B AH B AH B AH E EH E EH B AH

10 < t ≤ 15 B AH B AH D DH B AH E EH E EH D DH

15 < t ≤ 20 D DH B AH D DH B AH E EH E EH D DH

20 < t ≤ 25 D DH B AH D DH B BH E EH E EH E EH

25 < t ≤ 30 D DH B AH E EH (1) D DH E EH E EH E EH

30 < t ≤ 35 D DH B AH E EH D DH E EH E EH E EH

35 < t ≤ 40 D DH D DH E EH D DH F FH E EH E EH

40 < t ≤ 45 E EH D DH E EH D DH F FH E EH E EH

45 < t ≤ 50 E EH D DH E EH D DH F FH F FH E EH

(1) Grades D, DH are allowed for a single strake of side shell plating not more than 1,8 m wide from 0,3 m below the lowest icewaterline.

Note 1: Weather exposed plating includes weather-exposed plating of hull structures and appendages, as well as their outboardframing members, situated above a level of 0,3 m below the lowest ice waterline.Note 2: “NSS” and “HSS” mean, respectively: “Normal Strength Steel” and “Higher Strength Steel”.

Structural member Material class

Shell plating within the bow and bow intermediate icebelt hull areas (B, BI) II

All weather and sea exposed SECONDARY and PRIMARY (as defined in Pt B, Ch4, Sec 1, Tab 3 of the Rules forSteel Ships) structural members outside 0,4 Lui amidships I

Plating materials for stem and stern frames, rudder horn, rudder, propeller nozzle, shaft brackets, ice skeg, iceknife and other appendages subject to ice impact loads

II

All inboard framing members attached to the weather and sea-exposed plating including any contiguous inboardmember within 600 mm of the plating

I

Weather-exposed plating and attached framing in cargo holds of ships which, by nature of their trade, have theircargo hold hatches open during cold weather operations

I

All weather and sea exposed SPECIAL (as defined in Pt B, Ch4, Sec 1, Tab 3 of the Rules for Steel Ships) structuralmembers within 0,2 Lui from FE

II

��

��

��


NR 527, Sec 2

3 Corrosion/abrasion additions and steel renewal

3.1 Corrosion/abrasion additions

3.1.1 The value of the corrosion/abrasion additions tC to beapplied to shell plating is to be taken equal to the greater ofthe two following values:• tC obtained from Pt B, Ch 4, Sec 2, [3.1] of the Rules for

Steel Ships• tC obtained from Tab 7, subject to the fitting of an effec-

tive protection against corrosion and ice-induced abra-sion.

3.1.2 The value of the corrosion/abrasion additions tC to beapplied to all internal structures within the ice-strengthenedhull areas, including plated members adjacent to the shell,as well as stiffeners webs and flanges, is to be taken equal tothe greater of the two following values:• tC obtained from Pt B, Ch 4, Sec 2, [3.1] of the Rules for

Steel Ships• tC = 1,0 mm.

3.2 Steel renewal

3.2.1 Steel renewal for ice-strengthened structures isrequired when the gauged thickness is less than:tnet + 0,5 mm.

4 Design ice loads

4.1 General

4.1.1 For ships having one of the additional class notationsPOLAR CLASS or service notations Icebreaker, a glancingimpact on the bow is the design scenario for determiningthe scantlings required to resist ice loads.

4.1.2 The design ice load is characterized by an averagepressure pavg uniformly distributed over a rectangular loadpatch of height b and width w.

4.1.3 Within the bow area for POLAR CLASS 1 to POLARCLASS 7 or for Icebreaker 1 to Icebreaker 7, and for bowintermediate icebelt area for POLAR CLASS 6 or POLAR

CLASS 7, the ice load parameters (pavg , w and b) are func-tion of the actual bow shape. To determine the ice loadparameters, it is required to calculate the following ice loadcharacteristics for sub-regions of the bow area:• shape coefficient ci

• total glancing impact force Fi

• line load qi

• pressure pi

• load patch aspect ratio cARi .

4.1.4 In other ice-strengthened areas, the ice load parame-ters (pavg , wNonBow and bNonBow) are determined independ-ently of the hull shape and based on a fixed load patchaspect ratio cAR taken equal to: cAR = 3,6.

4.1.5 Bow with icebreaking formDesign ice loads calculated according to [4.3] are applica-ble for bow forms where (see Fig 4):• the buttock angle at the stem γstem is positive and less

than 80 degree, and• the normal frame angle θ at the centre of the foremost

sub-region is greater than 10 degree.

4.1.6 Bow with non-icebreaking formDesign ice loads calculated according to [4.3] are applica-ble to ships having the additional class notation POLARCLASS 6 or POLAR CLASS 7 and a bow form with verticalsides or a bulbous bow. This includes bows where the nor-mal frame angles θ at the considered sub-regions arebetween 0 and 10 degree (see Fig 4).

In addition, for bulbous bows, the design ice loads are notto be taken less than those given by considering bow withicebreaking form and by assuming:• the shape coefficient ci = 0,6

• the load patch aspect ratio cARi = 1,3

4.1.7 Other bow formsFor ships with bow forms other than those defined in[4.1.5] and [4.1.6], the design ice loads are to be speciallyconsidered by the Society.

4.1.8 Ship structures not directly subjected to ice loadsmay still experience inertial loads of stowed cargo andequipment resulting from ship/ice interaction. These inertialloads are to be considered in the design of such structures.

Table 7 : Total corrosion/abrasion additions tC for both sides of the shell plating

Hull area


1 to 3 4 and 5 6 and 7 1 to 3 4 and 5 6 and 7

tC, in mm, in case of effective protection tC, in mm, in the absence of effective protection

Bow (B)Bow Intermediate, Icebelt regions (BIi)

3,5 2,5 2,0 7,0 5,0 4,0

Bow Intermediate, Lower (BI)Midboby, Icebelt regions (Mi)Stern, Icebelt regions (Si)

2,5 2,0 2,0 5,0 4,0 3,0

Midbody, Lower, Bottom (M, Mb)

Stern, Lower, Bottom (S, Sb)Bow Intermediate, Bottom (BIb)

2,0 2,0 2,0 4,0 3,0 2,5


NR 527, Sec 2

4.2 Glancing impact load characteristics - Class factors

4.2.1 The parameters defining the glancing impact loadcharacteristics are reflected in the class factors listed in Tab 8and Tab 9.

4.3 Bow area

4.3.1 In the bow area, force FBow , line load qBow , pressurepBow and load patch aspect ratio cAR associated with theglancing impact load scenario are function of the hullangles measured at the upper ice waterline (UIWL). Theinfluence of the hull angles is captured through calculationof a bow shape coefficient ci . The hull angles are defined inFig 4.

4.3.2 The waterline length of the bow region is to bedivided into four sub-regions “i” of equal length. Forces Fi ,line loads qi , pressures pi , bow shape coefficients ci andload patch aspect ratios cARi are to be calculated withrespect to the mid-length position xi of each sub-region.

4.3.3 Shape coefficient

The shape coefficient ci , in each sub-region i of the bowarea, is to be obtained from the following formulae:

• for icebreaking form (see [4.1.5]):

ci = Min (ci, 1 ; ci, 2 ; ci, 3)

• for non-icebreaking form (see [4.1.6]):

ci = αi / 30

where:

ci, 3 = 0,60

Δui : Displacement at the upper ice waterline(UIWL), in t, to be taken not less than 5000 t

θi : Normal frame angle, in degree, in sub-region iof the bow area.

4.3.4 Load patch aspect ratio

The load patch aspect ratio cARi , in each sub-region i of thebow area, is to be obtained from the following formula:

cARi = 7,46 sin θi

to be taken not less than 1,3.

4.3.5 Design ice force

The force FBow , in kN, is to be obtained from the followingformula:

FBow = Max (Fi)

where:

Fi : Force in sub-region i of the bow area, in kN,taken equal to:



Δui : Displacement as defined in [4.3.3].

4.3.6 Line load

The line load qBow , in kN/m, is to be obtained from the fol-lowing formula:

qBow = Max (qi)

where:

qi : Line load in sub-region i of the bow area, inkN/m, taken equal to:



qi = 218,77 CQ Fi0,22

Table 8 : Glancing impact load characteristics - Class factors for icebreaking form

ci 1, 0 097 0 68 0 85, xi

Lui

------–

2

,–, αi

θi

--------=

ci 2,99 81 CF,

CC Δui0 64, θisin

-------------------------------=

Fi 12,02 ciCCΔui0 64,=

Fi 38,90 ciCCΔui0 47,=

qi14 79, CD F i

0 61,

cARi0 35,

-----------------------------------=

POLAR CLASS or

Icebreaker

CC

(crushing failure)

CF (flexural failure) CD

(load patch dimensions)

CΔ

(displacement)CL

(longitudinal strength)Brackish water Open sea

1 17,69 76,92 68,60 2,01 250000 7,46

2 9,89 54,45 46,80 1,75 210000 5,46

3 6,06 25,64 21,17 1,53 180000 4,17

4 4,50 17,05 13,48 1,42 130000 3,15

5 3,10 11,94 9,00 1,31 70000 2,50

6 2,40 8,70 5,49 1,17 40000 2,37

7 1,80 6,69 4,06 1,11 22000 1,81


NR 527, Sec 2

Table 9 : Glancing impact load characteristics - Class factors for non-icebreaking form

4.3.7 PressureThe pressure pBow , in kN/m2, is to be obtained from the fol-lowing formula:

pBow = Max (pi)

where:

pi : Pressure in sub-region i of the bow area, inkN/m2, taken equal to:



pi = 20,89 CP Fi0,56

4.3.8 Design load patchThe dimensions, in m, of the design load patch are to beobtained from the following formulae:

4.4 Hull areas other than the bow area

4.4.1 Design ice forceThe force FNonBow , in kN, is to be obtained from the follow-ing formulae:

• for Δui ≤ CΔ:

• for Δui > CΔ:

where:

Δui : Displacement at the upper ice waterline(UIWL), in t, to be taken not less than 10000 t.

4.4.2 Design ice force on the bottom area for navigation in shallow water

In case of navigation in shallow water (as defined in Sec 1,[1.5], the following force FNonBow , in kN, is to be consid-ered, in addition to the force FNonBow defined in [4.4.1]:

where:

T : Maximum fore draught in ice navigation, in m

CW : Waterline coefficient at draught T

CB : Block coefficient at draught T

Δui : Displacement as defined in [4.4.1]

V : Ship speed, in knots. The values given in Sec 1,Tab 3 may be considered as a guidance.

The highest requirements, determined using FNonBow from[4.4.1] and [4.4.2], are to be applied for the bottom scant-lings.

4.4.3 Line loadThe line load qNonBow , in kN/m, is to be obtained from thefollowing formula:

4.4.4 Design load patchThe dimensions, in m, of the design load patch are to beobtained from the following formulae:

4.5 Pressure within the design load patch

4.5.1 Average pressureIn the bow area and in hull areas other than the bow area,the average pressure pavg , in kN/m2, within a design loadpatch, is to be obtained from the following formula:

where:F : FBow or FNonBow , in kN, as appropriate for the

area under consideration.

4.5.2 Pressure concentrationThe peak pressure factors CPP , CPM and CPS defined in Tab10 are to be used to account for the pressure concentrationthat occurs within the load patch on structural members.

4.6 Hull area factor

4.6.1 The area factor CAF , associated with each hull area,reflects the relative magnitude of the load expected in thatarea. The area factor CAF for each hull area of POLARCLASS ships is listed in Tab 11 and the area factor CAF foreach hull area of Icebreaker ships is listed in Tab 12.In the event that a structural member spans the boundary ofa hull area, the largest hull area factor is to be used in thescantling determination of this member.

4.6.2 Stern icebelt and stern lower hull area factors are tobe specially considered for ships having propulsionarrangements with azimuthing thruster(s) or “podded” pro-pellers.

POLAR CLASSCC

(crushing failure)CQ

(line load)CP

(pressure)

6 3,43 2,82 0,65

7 2,60 2,33 0,65

pi 218 77 Fi0 22, CD

2cARi

0 3,,=

wBowFBow

qBow

----------=

bBowqBow

pBow

----------=

FNonBow 4 33 CC Δui0 64,,=

FNonBow 0 36 CC 12 02 CΔ0 64, 0 10 Δui CΔ–( ),+,[ ],=

FNonBowΔui V2

CB CW⁄ 0 5,–( ) T------------------------------------------ 10 3–=

qNonBow 9 451 CD F NonBow0 61,,=

wNonBowFNonBow

qNonBow

------------------=

bNonBowwNonBow

3 6,-------------------=

pavgF

w b--------=


NR 527, Sec 2

Table 10 : Peak pressure factors CPP , CPM and CPS

Table 11 : Hull area factor CAF for POLAR CLASS ships

Table 12 : Hull area factor CAF for Icebreaker ships

Structural member Peak pressure factor

Plating• transversely-framed CPP = (1,8 − s) ≥ 1,2

• longitudinally-framed CPP = (2,2 − 1,2 s) ≥ 1,5

Frames in transverse framing systems• with load distributing stringer(s) CPM = (1,6 − s) ≥ 1,0

• without load distributing stringer CPM = (1,8 − s) ≥ 1,2

Frames in bottom structures CPS = 1,0

Load carrying stringersSide longitudinalsWeb frames

• if Sw < 0,5 w: CPS = 2,0 − 2,0 Sw / w (1)

• if Sw ≥ 0,5 w: CPS = 1,0 (1)

(1) Sw : Web frame spacing, in m.

Hull areaPOLAR CLASS

1 2 3 4 5 6 7

Bow All 1,00 1,00 1,00 1,00 1,00 1,00 1,00

Bow Intermediate

Icebelt 0,90 0,85 0,85 0,80 0,80 1,00 1,00

Lower 0,70 0,65 0,65 0,60 0,55 0,55 0,50

Bottom (1) 0,55 0,50 0,45 0,40 0,35 0,30 0,25

Midbody

Icebelt 0,70 0,65 0,55 0,55 0,50 0,45 0,45

Lower 0,50 0,45 0,40 0,35 0,30 0,25 0,25

Bottom (1) 0,30 0,30 0,25 N.A. N.A. N.A. N.A.

Stern

Icebelt 0,75 0,70 0,65 0,60 0,50 0,40 0,35

Lower 0,45 0,40 0,35 0,30 0,25 0,25 0,25

Bottom (1) 0,35 0,30 0,30 0,25 0,15 N.A. N.A.

(1) In case of navigation in shallow water and for bottom scantling requirement determined using FNonBow defined in [4.4.2], CAF isto be taken equal to 1,00.

Note 1: N.A. indicates that strengthening for ice loads is not required in the hull area considered.

Hull areaIcebreaker

1 2 3 4 5 6 7

Bow All 1,00 1,00 1,00 1,00 1,00 1,00 1,00

Bow Intermediate

Icebelt 0,90 0,85 0,85 0,85 0,85 1,00 1,00

Lower 0,70 0,65 0,65 0,65 0,65 0,65 0,65

Bottom (1) 0,55 0,50 0,45 0,45 0,45 0,45 0,45

Midbody

Icebelt 0,70 0,65 0,55 0,55 0,55 0,55 0,55

Lower 0,50 0,45 0,40 0,40 0,40 0,40 0,40

Bottom (1) 0,30 0,30 0,25 0,25 0,25 0,25 0,25

Stern

Icebelt 0,95 0,90 0,80 0,80 0,80 0,80 0,80

Lower 0,55 0,50 0,45 0,45 0,45 0,45 0,45

Bottom (1) 0,35 0,30 0,30 0,30 0,30 0,30 0,30

(1) In case of navigation in shallow water and for bottom scantling requirement determined using FNonBow defined in [4.4.2], CAF isto be taken equal to 1,00.


NR 527, Sec 2

5 Longitudinal strength

5.1 Application

5.1.1 A ramming impact on the bow is the design scenariofor the evaluation of the longitudinal strength of the hull.Intentional ramming is not considered as a design scenariofor ships with vertical or bulbous bows (see Sec 1, [1.4.1]).Hence the longitudinal strength is not to be considered forships with buttock angle at the stem γstem greater than orequal to 80 degree.

5.1.2 For ships greater than or equal to 65 m in length, iceloads are to be combined with still water loads only. Thecombined stresses are to be compared against permissiblebending and shear stresses at different locations along theship length according to [5.3] and [5.4]. In addition, localbuckling strength is to be verified according to [5.5].

5.1.3 For ships less than 65 m in length, the normal stressonly due to ice loads is to comply with the checking criteriain [5.3.4]. In addition, the checking of shear stress and localbuckling strength may be required by the Society, on a case-by-case basis.

5.2 Hull girder ice loads

5.2.1 Design vertical ice force at the bow

The design vertical ice force at the bow FIB, in kN, is to beobtained from the following formula:

FIB = Min (FIB1 ; FIB2)

where:

FIB2 = 1200 CF

with:

CI1 : Coefficient equal to:

• for a simple wedge bow form (ceb = 1):

• for a spoon bow form (0 < ceb <1):

• for a landing craft bow form (ceb = 0):

CI2 : Coefficient, in kN/m, taken equal to:

CI2 = 10 AWP

Δui : Displacement at the upper ice waterline(UIWL), in t, to be taken not less than 10000 t

AWP : Ship waterplane area, in m2, at the upper icewaterline (UIWL)

γstem : Buttock angle at the stem, in degree, to bemeasured between the horizontal axis and thestem tangent at the upper ice waterline (UIWL)

ceb : Bow shape exponent that describes the water-plane at the upper ice waterline (UIWL), see Fig6 and Fig 7

LB : Bow length, in m, at the upper ice waterline(UIWL) as defined in Fig 7.

Figure 6 : Examples of ceb for Bui = 20 and LB = 16

When the general arrangement plan of the ship is available,the way to find ceb and LB is to select two points on the bow.If the coordinates of the two points are (x1, y1) and (x2, y2),the shape parameters ceb and LB are to be obtained from thefollowing formulae:

5.2.2 Design vertical ice bending momentThe design vertical ice bending moment MI , in kN⋅m, alongthe hull girder is to be obtained from the following formula:

where:

γstem : Buttock angle at the stem, in degree, defined in[5.2.1]

FIB : Design vertical ice force at the bow, in kN,defined in [5.2.1]

CH1 : Longitudinal distribution factor defined in Tab13.

Table 13 : Longitudinal distribution factor CH1

FIB1 1,505 C I10 15, C I2

0 35, γstemsin( )0 2, Δui0 5, CL=

CI1

Bui

2LB

---------0 9,

γstemtan( )1 8,-----------------------------=

CI1

Bui

LBceb 1 ceb+( )------------------------------

0 9,

γstemtan( )0 9 1 ceb+( ),

-------------------------------------------=

CI1Bui

0 9,

γstemtan( )0 9,-----------------------------=

Longitudinal position CH1

0 ≤ x/Lui < 0,50 2 x/Lui

0,50 ≤ x/Lui ≤ 0,70 1,0

0,70 < x/Lui < 0,95 − 2,8 x/Lui + 2,96

0,95 ≤ x/Lui ≤ 1,00 6 (1 − x/Lui)

20 16 12 8 4 00

2

4

6

8

10

12

18 14 10 6 2

0.050.10.2

0.5

1

Ceb

Y

y = Bui/2 (X/LB)Ceb

X= Lui - x

ceb

y2

y1

----- ln

Lui x– 2

Lui x– 1

----------------- ln

-----------------------------=

LB Lui x2–( ) 2y2

Bui

--------

1 ceb⁄–

=

MI0 1CH1 Lui FIB,

γstemsin( )0 2,---------------------------------=


NR 527, Sec 2

Figure 7 : Bow shape definition

5.2.3 Design vertical ice shear forceThe design vertical ice shear force QI along the hull girder,in kN, is to be obtained from the following formula:

QI = CH2 FIB

where:CH2 : Longitudinal distribution factor defined in Tab

14FIB : Design vertical ice force at the bow, in kN,

defined in [5.2.1].

Table 14 : Longitudinal distribution factor CH2

5.3 Normal stress

5.3.1 The normal stress σ, in N/mm2, induced by the verti-cal bending moments is to be obtained from the followingformulae:• at any point of the hull transverse section:

• at bottom:

• at deck:

where:

ZA : Gross section modulus, in m3, at any point ofthe hull transverse section, to be calculatedaccording to Pt B, Ch 6, Sec 1, [2.3.1] of theRules for Steel Ships

ZAB, ZAD : Gross section moduli, in m3, at bottom anddeck respectively, to be calculated according toPt B, Ch 6, Sec 1, [2.3.2] of the Rules for SteelShips.

5.3.2 The normal stress, in a structural member made inmaterial other than steel with a Young’s modulus E equal to2,06⋅105 N/mm2 and included in the hull girder transversesections as specified in Pt B, Ch 6, Sec 1, [2.1.6] of theRules for Steel Ships, is obtained from the following for-mula:

where:

σ : Normal stress, in N/mm2, in the structural mem-ber under consideration, calculated accordingto [5.3.1] considering this member as havingthe steel equivalent sectional area ASE defined inPt B, Ch 6, Sec 1, [2.1.6] of the Rules for SteelShips.

5.3.3 Checking criteria for ships greater than or equal to 65 m in length

It is to be checked that the normal stress σ or σ1 calculatedaccording to [5.3.1] or [5.3.2] is less than or equal to σALL ,with σALL defined in Tab 15.

Table 15 : Allowable normal stress σALL

y

y

bow stem

x

bow stem

ice waterline ice waterline

Bui/2Bui/2

LB

Spoon bow Wedge bow

y = ± Bui/2 (X/LB)Ceb

x

FEui FEui

Longitudinal position

CH2

Positive shear force

Negative shear force

0 ≤ x/Lui < 0,20,0

0,2 ≤ x/Lui ≤ 0,6 − 0,5

0,6 < x/Lui < 0,8

0,8 ≤ x/Lui < 0,9

0,00,9 ≤ x/Lui ≤ 1,0 1,0

2 5 xLui------,–

103------ x

Lui------ 2–

2 5 xLui------ 2–,

σ MSW S, MI+ZA

-------------------------- 10 3–=

σ MSW S, MI+ZAB

-------------------------- 10 3–=

σ MSW S, MI+ZAD

-------------------------- 10 3–=

σALL , in N/mm2

POLAR CLASS Icebreaker

ReH /Rm ≤ 0,7 0,80 ReH 0,60 ReH

ReH /Rm > 0,7 0,32 (ReH + Rm) 0,24 (ReH + Rm)

σ1E

2 06, 105---------------------- σ=


NR 527, Sec 2

5.3.4 Checking criteria for ships less than 65 m in length

It is to be checked that the normal stress σI is not to exceed50 N/mm2, where σI is obtained from the following formula:

A greater value of σI may be accepted if the total normalstress (σ or σ1 as defined in [5.3.1] or [5.3.2]) does notexceed the value of 100 N/mm2. In such a case, the stillwater bending moment is to be indicated by the Designer.

5.4 Shear stress

5.4.1 The shear stress induced by the shear forces is to beobtained through direct calculation analyses based on astructural model in accordance with Pt B, Ch 6, Sec 1, [2.6]of the Rules for Steel Ships.

The shear force corrections ΔQC and ΔQ are to be takeninto account, in accordance with, respectively, Pt B, Ch 6,Sec 2, [2.4.1] and Pt B, Ch 6, Sec 2, [2.4.2] of the Rules forSteel Ships.

5.4.2 The hull girder loads to be considered in these analy-ses are the vertical shear forces QSW and QI .

5.4.3 As an alternative to [5.4.1], the shear stresses inducedby the vertical shear forces QSW and QI may be obtainedthrough the simplified procedure in accordance with Pt B,Ch 6, Sec 2, [2.4] of the Rules for Steel Ships.

5.4.4 Checking criteria

It is to be checked that the shear stress τ calculated accord-ing to [5.4.1] or [5.4.3] is less than or equal to τALL , with τALL

defined in Tab 16.

Table 16 : Allowable shear stress τALL

5.5 Buckling

5.5.1 Plating

For plate panels subjected to compression and bending onone side, the normal stress σ, in N/mm2, calculated usingthe formulae in [5.3.1] but considering the net section mod-uli ZA,net , ZAB,net and ZAD,net of the section, is to fulfil the fol-lowing condition:

σ ≤ σc

where:

σc : Critical buckling stress in compression, inN/mm2, to be obtained from Pt B, Ch 7, Sec 1,[5.3.1] of the Rules for Steel Ships.

For plate panels subjected to shear, the shear stress τ, inN/mm2, calculated considering the net scantlings of the sec-tion, is to fulfil the following condition:

τ ≤ τc

where:

τc : Critical shear buckling stress, in N/mm2, to beobtained from Pt B, Ch 7, Sec 1, [5.3.2] of theRules for Steel Ships.

5.5.2 Ordinary stiffeners

For plating constituting the web of ordinary stiffeners, thenormal stress σ, calculated using the formulae in [5.3.1] butconsidering the net section moduli ZA,net , ZAB,net and ZAD,net

of the section, in N/mm2, is to fulfil the following condition:

σ ≤ σc

where:

σc : Critical buckling stress in compression, inN/mm2, to be obtained from Pt B, Ch 7, Sec 1,[5.3.1] of the Rules for Steel Ships.

In addition, the normal stress σ, in N/mm2, applied to anordinary stiffener is to fulfil the following condition:

where:

σc : Critical buckling stress of a stiffener, in N/mm2,to be obtained from Pt B, Ch 7, Sec 2, [4.3.1] ofthe Rules for Steel Ships.

6 Shell plating

6.1 General

6.1.1 The shell plate thickness, in mm, is to be not less thanthe value obtained from the following formula:

t = tnet + tC

6.2 Net thickness

6.2.1 Transversely-framed plating

The net thickness, in mm, of transversely-framed plating(α1 ≥ 70°) is to be not less than the value obtained from thefollowing formula:

where:

b : Height of design load patch, in m, to be takennot greater than ( − s/4)

α1 : Smallest angle, in degree, between the chordof the waterline and the ordinary stiffeners (seeFig 8).

τALL , in N/mm2

POLAR CLASS Icebreaker

ReH /Rm ≤ 0,7 0,46 ReH 0,34 ReH

ReH /Rm > 0,7 0,18 (ReH + Rm) 0,14 (ReH + Rm)

σIMI

ZA

------ 10 3–=

σ σc

1 1,---------≤

tnet 15 8 sCAF CPP pavg

ReH

--------------------------- 1

1 s2b-------+

-----------------,=


NR 527, Sec 2

Figure 8 : Shell framing angle

6.2.2 Longitudinally-framed plating

The net thickness, in mm, of longitudinally-framed plating(α1 ≤ 20°) is to be not less than the value obtained from thefollowing formulae:

• when b ≥ s:

• when b < s:

where:

: Distance between frame supports, in m, equalto the frame span as given in [7.1.4], but notreduced for any fitted end brackets. When aload-distributing stringer is fitted, the length need not be taken larger than the distance fromthe stringer to the most distant frame support.

6.2.3 Obliquely-framed plating

For obliquely-framed plating (70°> α1 > 20°), the net thick-ness, in mm, is to be obtained by linear interpolationbetween the thicknesses from [6.2.1] and [6.2.2].

7 Framing scantlings

7.1 General

7.1.1 The term “framing member” refers to transverse andlongitudinal ordinary stiffeners, load-carrying stringers andweb frames in the areas of the hull exposed to ice pressure.Where load-distributing stringers have been fitted, their

arrangement is to be in accordance with the applicablerequirements of Part B, Chapter 4 of the Rules for Steel Shipsand their scantlings are to be in accordance with the appli-cable criteria defined in Pt B, Ch 7, Sec 3 of the Rules forSteel Ships.

7.1.2 The strength of a framing member is dependent uponthe fixity that is provided at its supports. Fixity can beassumed where framing members are either continuousthrough the support or attached to a supporting section witha connection bracket. In other cases, simple support is to beassumed unless the connection can be demonstrated to pro-vide significant rotational restraint. Fixity is to be ensured atthe support of any framing which terminates within an ice-strengthened area.

7.1.3 The details of framing member intersection with otherframing members, including plated structures, as well as thedetails for securing the ends of framing members at support-ing sections, are to be in accordance with the applicablerequirements of Part B, Chapter 4 of the Rules for SteelShips.

7.1.4 The span of a framing member is to be determined inaccordance with Pt B, Ch 4, Sec 3, [3.2] of the Rules forSteel Ships. If brackets are fitted, the span may be taken athalf-length of the brackets. Brackets are to be defined toensure stability in the elastic and post-yield responseregions.

7.1.5 When calculating the section modulus and sheararea of a framing member, net thicknesses of the web,flange (if fitted) and attached shell plating are to be used.The shear area of a framing member may include that mate-rial contained over the full depth of the member, i.e. webarea including portion of flange, if fitted, but excludingattached plating.

framingmember

waterline

View normal to shell View normal to shell

Oblique viewOblique view

framingmember


ReH

--------------------------- 1

1 s2------+

----------------,=


ReH

--------------------------- 2 bs--- b

s---

2

– 1

1 s2------+

----------------,=


NR 527, Sec 2

7.2 Actual net effective shear area of ordinary stiffeners

7.2.1 The actual net effective shear area Aw , in cm2, of atransverse or longitudinal ordinary stiffener is given by:

where (see Fig 9):

h : Height of the stiffener, in mm

ϕw : Angle, in degree, between the attached plateand the web of the stiffener, measured at mid-span of the stiffener.

Figure 9 : Dimensions of ordinary stiffeners

7.3 Actual net effective plastic section modulus of ordinary stiffeners

7.3.1 When the net cross-sectional area of the attachedplate Ap exceeds the net cross-sectional area of the ordinarystiffener Aw’ + Af , the plastic neutral axis PNA is assumed tobe tangent to the uppermost edge of the attached plate.

The actual net effective plastic section modulus wp of such atransverse or longitudinal ordinary stiffener, in cm3, is givenby:

where:

Ap’ : Net cross-sectional area of the stiffener, in cm2,taken equal to:

Ap’ = Aw’ + Af

xp : Distance, in mm, between the centre of gravityof area Ap and PNA, taken equal to:

Aw’ : Net cross-sectional area of the stiffener web, incm2, taken equal to:

xw : Distance, in mm, between the centre of gravityof area Aw’ and PNA, taken equal to:

Af : Net cross-sectional area of the stiffener flange,in cm2, taken equal to:

xf : Distance, in mm, between the centre of gravityof area Af and PNA, taken equal to:

xf = hfc sin ϕw − bw cos ϕw

hfc : Height, in mm, of the stiffener, measured up tothe centre of the flange area, see Fig 9

bw : Distance, in mm, from the mid-thickness planeof the stiffener web to the centre of the flangearea, see Fig 9

ϕw : As defined in [7.2.1].

7.3.2 When the net cross-sectional area Aw’ + Af of the stiff-ener exceeds the net cross-sectional area of the attachedplate Ap , the plastic neutral axis PNA is located at a dis-tance za above the attached plate, in mm, given by:

The actual net effective plastic section modulus wp of such atransverse or longitudinal ordinary stiffener, in cm3, is givenby:

where:Ap : Net cross-sectional area of the attached plate, in

cm2, taken equal to:

Ap = 10 tp s

xp : Distance, in mm, between the centre of gravityof area Ap and PNA, taken equal to:

Awa : Net cross-sectional area, in cm2, of the part ofthe stiffener located above PNA, taken equal to:

xwa : Distance, in mm, between the centre of gravityof area Awa and PNA, taken equal to:

Awb : Net cross-sectional area, in cm2, of the part ofordinary stiffener located below the PNA, takenequal to:

xwb : Distance, in mm, between the centre of gravityof area Awb and PNA, taken equal to:

Aw htwϕw( )sin

100-------------------=

�

��

��

��

��

��

��

�

ϕ� ��

wpAp′ xp Aw′ xw Af xf+ +

10---------------------------------------------------=

xp Min Aw′ Af+

20 s-------------------- ; tp

2---

=

Aw′ hw tw

100-----------=

xwhw ϕwsin

2---------------------=

Afbf tf

100----------=

za100 Af hw tw 1000 tp s–+( ) ϕwsin

2 tw

--------------------------------------------------------------------------------=

wpAp xp Awa xwa Awb xwb Af xf+ + +( )

10---------------------------------------------------------------------------------=

xp z= atp

2---+

Awa hwza

ϕwsin---------------–

tw

100----------=

xwa hwza

ϕwsin---------------–

ϕwsin2

---------------=

Awbtw za

100 ϕwsin-------------------------=

xwbza

2----=


NR 527, Sec 2

Figure 10 : Definition of web stiffening

xf : Distance, in mm, between the centre of gravityof area Af and PNA, taken equal to:

xf = hfc sin ϕw − bw cos ϕw − za

hfc , bw : As defined in [7.3.1]

ϕw : As defined in [7.2.1].

7.4 Structural stability

7.4.1 The ratio of web height hw to the net web thickness twof any framing member is to fulfil the following condition:

• for flat bar sections:

• for bulb, tee and angle sections:

7.4.2 The framing members for which it is not practicableto meet the requirements of [7.4.1] (e.g. load carryingstringers or deep web frames) are required to have effec-tively stiffened webs. The scantlings of the web stiffeners areto ensure the structural stability of the framing members.

For these framing members, the minimum net web thick-ness tw , in mm, is given by the following formula:

where (see Fig 10):

hw : Web height, in mm, of the member under con-sideration

hf : Height, in mm, of the framing members pene-trating the member under consideration, takenequal to 0 in case of no penetration

s1 : Spacing, in m, between the supporting struc-tures oriented perpendicular to the memberunder consideration.

7.4.3 In addition to [7.4.1] and [7.4.2], the following con-dition is to be satisfied:

where:

tnet : Net thickness, in mm, of the attached plate inway of the framing member

ReH : Minimum yield stress of the shell plate, inN/mm2, in way of the framing member.

7.4.4 For the welded profiles, the following conditions areto be satisfied:

where bout is the width of outstand of the flange, in mm.

7.5 Ordinary stiffeners in bottom structures and transverse ordinary stiffeners in side structures

7.5.1 The ordinary stiffeners in bottom structures (i.e. hullareas BIb, Mb and Sb) and the transverse ordinary stiffenersin side structures are to be designed such that the combinedeffects of shear and bending do not exceed the plasticstrength of the stiffener. The plastic strength is defined bythe magnitude of the midspan load that causes the develop-ment of a plastic collapse mechanism. For bottom structurethe design load patch is to be applied with the height b par-allel to the stiffener direction.

7.5.2 The net effective shear area Aw , in cm2, of the ordi-nary stiffeners, as defined in [7.2], is to comply with the fol-lowing condition:

Aw ≥ At

where:

LP : Length of the span loaded portion, in m, takenequal to the lesser of and b

CP : Peak pressure factor, to be taken equal to:

• CPM for transverse stiffeners in side structures

• CPS for stiffeners in bottom structures.

��

��

��

hw

tw

------ 282ReH

------------≤

hw

tw

------ 805ReH

------------≤

tw2 63 hw 0 8 hf,–( ) ReH,

5 34, 4hw 0 8 hf,–

s1

--------------------------- 10 3–

2

+

------------------------------------------------------------------------- 10 3–=

tw 0 35 tnetReH

235----------,≥

bf

tw

---- 5≥

bout

tf

-------- 155ReH

------------≤

At8 67 LP s CAF CP pavg,

ReH

------------------------------------------------=


NR 527, Sec 2

Figure 11 : Simple and fixed framing supports

7.5.3 The net effective plastic section modulus wp , in cm3,of the ordinary stiffeners with their attached plating, asdefined in [7.3], is to comply with the following condition:

where:

LP : As defined in [7.5.2]

A1 = Max (A1A ; A1B)

A1A : Coefficient taken equal to (see Fig 11):

• for stiffeners with one simple support out-side the ice-strengthened areas:

• for stiffeners with one fixed support outsidethe ice-strengthened areas or with supportswithin the ice-strengthened areas (see[7.1.2]):

A1B : Coefficient taken equal to:

At : As defined in [7.5.2]

Aw : As defined in [7.2.1]

kz : Sum of individual plastic section moduli offlange and attached plating as fitted, in cm3,taken equal to:

• in general:

• when the stiffener is arranged with endbracket(s):

kz = 0

kw : Coefficient taken equal to:

Af : As defined in [7.3.1].

7.6 Longitudinal ordinary stiffeners in side structures

7.6.1 Longitudinal ordinary stiffeners in side structures areto be dimensioned such that the combined effects of shearand bending do not exceed the plastic strength of the stiff-ener. The plastic strength is defined by the magnitude of themidspan load that causes the development of a plastic col-lapse mechanism.

7.6.2 The net effective shear area Aw , in cm2, of longitudi-nal ordinary stiffeners, as defined in [7.2], is to fulfil the fol-lowing condition:

Aw ≥ AL

where:

with:

b1 : Coefficient defined as follows:

• for b/s < 2:

• for b/s ≥ 2:

7.6.3 The net effective plastic section modulus wp, in cm3,of the longitudinal ordinary stiffeners with their attachedplating, as defined in [7.3], is to fulfil the following condi-tion:

where:

A2 : Coefficient taken equal to:

kw : As defined in [7.5.3]

AL , b1 : As defined in [7.6.2]

Aw : As defined in [7.2.1].

��

��

��

��

��

wp LP 1 0 5LP

------,–

sCAF CP pavg A1

4 ReH

---------------------------------- 103≥

A1A1

1 5 0 5 kw 1At

2

Aw2------– 1–,+,

--------------------------------------------------------------------=

A1A1

2 kw 1At

2

Aw2------– 1–+

---------------------------------------------------=

A1B

1 1

2At

Aw

------ 10 5 LP,

----------------–

-------------------------------------------–

0 275, 1 44 kz0 7,,+

----------------------------------------------------------=

kzbf tf

2 500 stp2+

4000 wp

--------------------------------=

kw1

1 2Af

Aw

------+--------------------=

AL8 67 b1CAFCPS pavg,

ReH

-------------------------------------------------=

b1 b 0 3 s,–( ) 1 0 25 bs---,–

with b1 0≥=

b1 s 1 0 3 sb---,–

=

wp

2 b1 CAF CPS pavg A2

8 REH

--------------------------------------------- 103≥

A21

2 kw 1AL

2

Aw2------– 1–+

---------------------------------------------------=


NR 527, Sec 2

7.7 Oblique ordinary stiffeners

7.7.1 The net effective shear area, in cm2, and the net effec-

tive plastic section modulus, in cm3, of the oblique ordinarystiffeners (70° > α1 > 20°) are to be obtained by linear inter-

polation between the values obtained from [7.5] and [7.6].

7.8 Web frames and load-carrying stringers

7.8.1 Web frames and load-carrying stringers are to bedesigned to withstand the ice load patch as defined in [4].The load patch is to be applied at locations where thecapacity of these members, under the combined effects ofbending and shear, is minimised. Special attention is to bepaid to the shear capacity in way of lightening holes and ofcut-outs at the intersection of structural members.

7.8.2 For the scantling determination of load-carryingstringers, web frames supporting ordinary stiffeners, or webframes supporting load-carrying stringers that form part of astructural grillage system, direct structural calculationsaccording to the methodologies given in Pt B, Ch 7, Sec 3 ofthe Rules for Steel Ships are to be used. The scantlings ofthe members forming part of a grillage are to be defined sothat the combined effects of shear and bending fulfil the cri-teria given in [7.8.4].

7.8.3 Where the structural configuration is such that themembers do not form part of a grillage system, the appropri-ate peak pressure factor defined in Tab 10 is to be used.

7.8.4 Criteria for direct structural calculations

When the scantlings are determined from direct structuralcalculations, the following criteria are to be considered:

• the web plates and flange elements in compression andshear are to comply with the relevant buckling criteria

• the nominal shear stress in web plates is to be less thanthe maximum values defined in Tab 17

• the nominal von Mises stress in flanges is to be less thanthe maximum values defined in Tab 17.

7.8.5 The scantlings of web frames and load-carryingstringers are to meet the structural stability requirements of[7.4].

Table 17 : Maximum stresses for direct calculations

8 Plated structures

8.1 General

8.1.1 Plated structures are those stiffened plate elements incontact with the hull and subjected to ice loads. Theserequirements are applicable to an inboard extent which isthe lesser of:

• web height of adjacent parallel web frame or stringer,and

• 2,5 times the depth of framing that intersects the platedstructure.

8.1.2 The thickness of the plating and the scantlings ofattached stiffeners are to be such that the degree of end fix-ity necessary for the shell framing is ensured.

8.1.3 The stability of the plated structure is to adequatelywithstand the ice loads defined in [4].

9 Stem and stern arrangement

9.1 Fore part

9.1.1 Stem

The stem may be made of rolled, cast or forged steel or ofshaped steel plates.

A sharp edged stem (see Fig 12) improves the manoeuvra-bility of the ship in ice and is particularly recommended forships less than 150 m in length.

The plate thickness of a shaped plate stem and, in the caseof a blunt bow, any part of the shell which forms an angle of30° or more to the centreline in a horizontal plane, is to benot less than 1,3 times the thickness of the adjacent shellplating, calculated according to [6.2].

The stem and the part of a blunt bow defined above are tobe supported by floors or brackets spaced not more than600 mm apart and having a thickness at least equal to halfthe plate thickness.

The reinforcement of the stem is to be extending from thekeel to the upper level of the Bow region.

Figure 12 : Sharp edged stem - Example

Type of three dimensional model

Maximum shear stress

Maximum von Mises stress

Beam model 0,50 ReH ReH

Finite element model 0,57 ReH 1,15 ReH


NR 527, Sec 2

9.2 Aft part

9.2.1 An extremely narrow clearance between the propel-ler blade tip and the sternframe is to be avoided so as not togenerate very high loads on the blade tip.

9.2.2 On twin and triple screw ships, the ice strengtheningof the shell and framing is to be extended to the double bot-tom over at least 1,5 m forward and aft of the side propel-lers.

9.2.3 Shafting and sterntubes of side propellers are gener-ally to be enclosed within plated bossings. If detached strutsare used, their design, strength and attachment to the hullare to be examined by the Society on a case-by-case basis.

9.2.4 A wide transom stern extending below the UIWL seri-ously impedes the capability of the ship to run astern in ice,which is of paramount importance.Consequently, a transom stern is normally not to beextended below the UIWL. Where this cannot be avoided,the part of the transom below the UIWL is to be kept as nar-row as possible.

The part of a transom stern situated within the ice strength-ened area is to be strengthened as required for the midshipregion.

9.2.5 Where azimuth propulsion systems are fitted, theincrease in ice loading of the aft region and the stern area isto be considered, in the design of the aft/stern structure, ona case-by-case basis by the Society.

10 Hull outfittings

10.1 Rudders

10.1.1 The scantlings of the rudder post, rudder stock, pint-les, steering gear, etc. as well as the capacity of the steeringgear are to be determined according to Pt B, Ch 9, Sec 1 ofthe Rules for Steel Ships.The speed to be used in these calculations is the greater ofthe maximum ahead service speed and the speed indicatedin Tab 18. When the speed indicated in Tab 18 is used, thecoefficients r1 and r2, defined in Pt B, Ch 9, Sec 1, [2.1.2] ofthe Rules for Steel Ships, are to be taken equal to, irrespec-tive of the rudder type profile: r1 = r2 = 1,0.

Within the ice-strengthened zone, the thickness of rudderplating and diaphragms is to be not less than that requiredfor the shell plating of the stern region.

Table 18 : Minimum speed

10.1.2 The rudder stock and the upper edge of the rudderare to be protected against ice pressure by an ice knife orequivalent means.

10.2 Arrangements for towing

10.2.1 A mooring pipe with an opening not less than250 mm by 300 mm, a length of at least 150 mm and aninner surface radius of at least 100 mm is to be fitted in thebow bulwark on the centreline.

10.2.2 A bit or other means of securing a towline, dimen-sioned to withstand the breaking strength of the ship’s tow-line, is to be fitted.

10.2.3 On ships with a displacement less than 30000 t, thepart of the bow extending to a height of at least 5 m abovethe UIWL and at least 3 m back from the stem is to bestrengthened to withstand the stresses caused by fork tow-ing. For this purpose, intermediate ordinary stiffeners are befitted and the framing is to be supported by stringers ordecks.

Note 1: It is to be noted that for ships of moderate size (displace-ment less than 30000 t), fork towing is, in many situations, the mostefficient way of assisting in ice. Ships with a bulb protruding morethan 2,5 m forward of the forward perpendicular are often difficultto be towed in this way. The Administrations reserve the right todeny assistance to such ships if the situation warrants such a deci-sion.

POLAR CLASS or Icebreaker Speed (knots)

1 26

2 24

3 23

4 22

5 21

6 20

7 18


NR 527, Sec 3

SECTION 3 MACHINERY REQUIREMENTS FOR POLAR CLASS

AND ICEBREAKER SHIPS

Symbols

ai : Longitudinal impact acceleration, in m/s2

at : Transverse impact acceleration, in m/s2

av : Vertical impact acceleration, in m/s2

c : Actual chord length of the cylindrical root sec-tion of blade at weakest section, in m

c0,7 : Length of the blade chord at radius 0,7 R, in mCq , αi : Parameters for ice torque excitation of shaft lined : Propeller hub diameter, in mD : Propeller diameter, in mDlimit : Limit diameter between square or linear law for

ice load vs propeller diameter, in mEAR : Expanded blade area ratioFb : Maximum backward blade force, in kN, as

defined in [3.2.1]Fex : Blade failure load, in kNFf : Maximum forward blade force, in kN, as

defined in [3.2.1]Fi : Total force normal to shell plating in bow area

due to oblique ice impact, in kN, as defined inSec 2, [4.3.5]

FIB : Vertical impact force, in kN, as defined in Sec 2,[5.2.1]

H : Distance from the waterline to the point beingconsidered, in m

Hice : Ice thickness for machinery strength design, inm, as defined in [3.1.1]

Lui : Rule length, in m, as defined in Pt B, Ch 1, Sec2, [3.1] of the Rules for Steel Ships, but meas-ured at the upper ice waterline (UIWL)

n : Rotational propeller speed at bollard condition,in rps, as defined in [3.3.1]

nn : Nominal rotational propeller speed at MCR, infree running open water condition, in rps

NQ : Number of propeller revolution during a millingsequence

P0,7 : Propeller pitch at radius 0,7 R, in mpice : Ice pressure, in MPaQ(ϕ) : Excitation torque of propeller shaft, in kN⋅mQe : Actual maximum engine torque at considered

speed, in kN⋅mQmax : Maximum torque on a propeller due to ice-pro-

peller interaction, in kN⋅mQsmax : Maximum blade spindle torque, in kN⋅mr : Actual radius of the cylindrical root section of

blade at weakest section, in m

R : Outside radius of the propeller, in m

S : Acceptance criteria

Sice : Ice strength index for blade ice force, as definedin [3.1.1]

Sqice : Ice strength index for blade ice torque, asdefined in [3.1.1]

t : Actual thickness of the cylindrical root sectionof blade at weakest section, in m

T : Nominal propeller thrust at MCR at free runningopen water conditions, in kN

t0,7 : Maximum thickness at radius 0,7 R, in m

Tb : Maximum backward propeller ice thrust appliedto the shaft, in kN

ted : Actual blade edge thicknesses, in m

tedge : Minimum calculated blade edge thickness, in m

Tf : Maximum forward propeller ice thrust appliedto the shaft, in kN

Tn : Propeller bollard thrust, in kN

ttip : Tip thickness, in m

Z : Number of propeller blades

γstem : Buttock angle at the stem, in degree, to bemeasured between the horizontal axis and thestem tangent at the upper ice waterline (UIWL)

Δui : Ship displacement at the upper ice waterline(UIWL), in t

σ0,2 : 0,2% proof stress for blade material, in N/mm2

σall : Allowed blade stress for maximum ice load, inN/mm2

σcalc : Calculated blade stress for maximum ice load,in N/mm2

σref : Reference stress for blade material, in N/mm2

σu : Ultimate tensile strength for blade material, inN/mm2

φ : Maximum friction angle between steel and ice,in degree, normally taken equal to 10°.

1 General

1.1 Application

1.1.1 This Section applies to ships having one of the addi-tional class notations POLAR CLASS or one of the servicenotations Icebreaker and gives requirements for main pro-pulsion, steering gear, emergency and auxiliary systemsessential for the safety of the ship.


NR 527, Sec 3

1.2 Drawings and particulars to be submitted

1.2.1 The following drawings and particulars are to be sub-mitted to the Society:

• details of the environmental conditions

• detailed drawings of the main propulsion machinery.Description of the main propulsion, steering, emergencyand essential auxiliaries are to include operational limi-tations. Information on essential main propulsion loadcontrol functions

• description detailing how main, emergency and auxil-iary systems are located and protected to prevent prob-lems from freezing, ice and snow and evidence of theircapability to operate in intended environmental condi-tions

• calculations and documentation indicating compliancewith the requirements of this Section.

1.3 Principle of design review for main propulsion and machinery

1.3.1 Main propulsion and machinery are reviewed follow-ing the two successive steps as defined in [1.3.2] and [1.3.3].

1.3.2 Calculation of loads and stresses

a) Calculation of loads due to interaction between the pro-peller blade and the ice, depending on the additionalclass notation POLAR CLASS or on the service notationIcebreaker and the running conditions (see [3])

b) Calculation of the blade stress for each load case underthe application of the calculated loads on a finite ele-ment model (see [3.3] and [3.4])

c) Calculation of the total ice torque on the propulsion linedue to the blade ice impacts (see [3.5.1])

d) Calculation of the maximum thrusts applied to the pro-pulsion line (see [3.5.2])

e) Calculation of the blade failure load of the propeller(see [3.5.3]).

1.3.3 Design requirements

a) The propulsion line is to be designed as to ensure a suf-ficient fatigue strength under dynamic excitation calcu-lated as per [1.3.2] item c) and loads calculated as per[1.3.2] item d) (see [4.1] and [4.2])

b) In respect of pyramidal strength principle, the propul-sion line is also to be designed as to withstand a loadcorresponding to the propeller blade failure load as per[1.3.2] item e)

c) Evaluation of propeller blade strength according to cal-culated stresses in [1.3.2] item b) and material charac-teristics (see [4.3])

d) Required capability of prime movers (see [4.4])

e) Required capabilities for acceleration loads due toship/ice contacts (see [5])

f) Miscellaneous requirements for auxiliaries and generalarrangement (see [6], [7], [8] and [9]).

1.4 System design

1.4.1 Machinery and supporting auxiliary systems are to bedesigned, constructed and maintained to comply with therequirements of “periodically unmanned machinery spaces”with respect to fire safety. Any automation plant (i.e. control,alarm, safety and indication systems) for essential systemsinstalled is to be maintained to the same standard.

1.4.2 Systems, subject to damage by freezing, are to bedrainable.

1.4.3 Single screw ships having one of the additional classnotations POLAR CLASS 1 to POLAR CLASS 5 inclusive, orhaving one of the service notations Icebreaker, are to havemeans provided to ensure sufficient ship operation in thecase of propeller damage including CP-mechanism.

2 Materials

2.1 Materials exposed to sea water

2.1.1 Materials exposed to sea water, such as propellerblades, propeller hub and blade bolts are to have an elon-gation not less than 15% on a test piece the length of whichis five times the diameter.

Charpy V impact test is to be carried out for other thanbronze and austenitic steel materials. Test pieces taken fromthe propeller castings are to be representative of the thickestsection of the blade. An average impact energy value not tobe less than 20 J taken from three Charpy V tests is to beobtained at −10ºC.

2.2 Materials exposed to sea water temperature

2.2.1 Materials exposed to sea water temperature are to beof steel or other approved ductile material.

An average impact energy value not to be less than 20 Jtaken from three tests is to be obtained at −10ºC.

2.3 Material exposed to low air temperature

2.3.1 Materials of essential components exposed to low airtemperature are to be of steel or other approved ductilematerial.

An average impact energy value not to be less than 20 Jtaken from three Charpy V tests is to be obtained at 10ºCbelow the lowest design temperature.

3 Ice interaction load

3.1 Ice class factors

3.1.1 Tab 1 lists the design ice thickness Hice and the icestrength indexes Sice and Sqice to be used for estimation ofthe propeller ice loads, according to the additional classnotations POLAR CLASS or service notations Icebreaker asdefined in Sec 1.


NR 527, Sec 3

Table 1 : Design ice thickness Hice

and ice strength indexes Sice and Sqice

3.2 Propeller ice interaction

3.2.1 This Section covers open and ducted type propellerssituated at the stern of a ship having controllable pitch orfixed pitch blades. Ice loads on bow propellers and pullingtype propellers are to receive special consideration. Thegiven loads are expected, single occurrence, maximum val-ues for the whole ships service life for normal operationalconditions. These loads do not cover off-design operationalconditions, for example when a stopped propeller isdragged through ice. This Section applies also for azimuth-ing (geared and podded) thrusters considering loads due topropeller ice interaction. However, ice loads due to iceimpacts on the body of azimuth thrusters are not covered bythis Section.

The loads given in the present Article are total loads (unlessotherwise stated) during ice interaction and are to beapplied separately (unless otherwise stated) and areintended for component strength calculations only. The fol-lowing different loads are to be applied separately:

• Force Fb bending a propeller blade backwards when thepropeller mills an ice block while rotating ahead

• Force Ff bending a propeller blade forwards when a pro-peller interacts with an ice block while rotating ahead.

3.3 Design ice loads for open propeller

3.3.1 Maximum backward blade force Fb

The maximum backward blade force Fb, in kN, is equal to:

• when D < Dlimit :

• when D ≥ Dlimit :

where:

Dlimit = 0,85 (Hice)1,4

n : Rotational propeller speed, in rps, taken at bol-lard condition (i.e. at the minimum ship speedin ice). If not know, n is to be as follows:

• n = nn for CP propellers and FP propellersdriven by turbine or electric motor

• n = 0,85 nn for FP propellers driven by die-sel engine.

Fb is to be applied as a uniform pressure distribution to anarea on the back (suction) side of the blade for the followingload cases (see Tab 2):

• Load case 1: from 0,6 R to the tip and from the bladeleading edge to a value of 0,2 chord length

• Load case 2: a load equal to 50% of the Fb is to beapplied on the propeller tip area outside of 0,9 R

• Load case 5: for reversible propellers, a load equal to60% of the Fb is to be applied from 0,6 R to the tip andfrom the blade trailing edge to a value of 0,2 chordlength.

3.3.2 Maximum forward blade force Ff

The maximum forward blade force Ff, in kN, is equal to:



where:

Ff is to be applied as a uniform pressure distribution to anarea on the face (pressure) side of the blade for the follow-ing loads cases (see Tab 2):

• Load case 3: from 0,6 R to the tip and from the bladeleading edge to a value of 0,2 chord length

• Load case 4: a load equal to 50% of the Ff is to beapplied on the propeller tip area outside of 0,9 R

• Load case 5: for reversible propellers, a load equal to60% of Ff is to be applied from 0,6 R to the tip and fromthe blade trailing edge to a value of 0,2 chord length.

3.3.3 Maximum blade spindle torque Qsmax

Spindle torque Qsmax around the spindle axis of the blade fit-ting is to be calculated for the both load cases described in[3.3.1] for Fb and in [3.3.2] for Ff .

These spindle torque values are not to be less than the fol-lowing default value, in kN⋅m:

Qsmax = 0,25 F c0,7

where:

F : Blade force, in kN⋅m, equal to Fb or Ff , which-ever has the greater absolute value.


Hice , in m

Sice Sqice

1 4,00 1,20 1,15

2 3,50 1,10 1,15

3 3,00 1,10 1,15

4 2,50 1,10 1,15

5 2,00 1,10 1,15

6 1,75 1,00 1,00

7 1,50 1,00 1,00

Fb 27– Sice= EARZ-----------

0 3,

nD( )0 7, D2

Fb 23– SiceEAR

Z-----------

0 3,

Hice1 4, nD( )0 7, D=

Ff 250 EARZ----------- D2=

Ff 500 1

1 dD----–

-------------- HiceEAR

Z----------- D=

Dlimit2

1 dD----–

-------------- Hice=


NR 527, Sec 3

Table 2 : Load cases for open propeller

Load case N°

Force Loaded areaRight handed propeller blade

seen from back

1 Fb

Uniform pressure applied on the back of theblade (suction side) to an area from 0,6 R to tipand from the leading edge to 0,2 times thechord length

2 50% of Fb

Uniform pressure applied on the back of theblade (suction side) on the propeller tip areaoutside of 0,9 R radius

3 Ff

Uniform pressure applied on the blade face(pressure side) to an area from 0,6 R to the tipand from the leading edge to 0,2 times thechord length

4 50% of Ff

Uniform pressure applied on propeller face(pressure side) on the propeller tip area outsideof 0,9 R radius

560% of Ff or Fb

which one is greater

Uniform pressure applied on propeller face(pressure side) to an area from 0,6 R to the tipand from the trailing edge to 0,2 times thechord length

��

��

��

��

��

��

��

��


NR 527, Sec 3

3.3.4 Maximum propeller ice torque applied to the propeller

The maximum propeller ice torque Qmax , in kN⋅m, is equalto:



where:

Dlimit = 1,81 Hice

3.3.5 Maximum propeller ice thrust applied to the shaft

The maximum propeller ice thrusts Tf and Tb , in kN, areequal to:

• forwards:

Tf = 1,1 Ff

• backwards:

Tb = 1,1 Fb

3.4 Design ice loads for ducted propeller

3.4.1 Maximum backward blade force Fb

The maximum backward blade force Fb , in kN, is equal to:



where:

Dlimit = 4,0 Hice

Fb is to be applied as a uniform pressure distribution to anarea on the back side of the blade for the following loadcases (see Tab 3):

• Load case 1: on the back of the blade from 0,6 R to thetip and from the blade leading edge to a value of 0,2chord length

• Load case 5: for reversible rotation propellers, a loadequal to 60% of Fb is applied on the blade face from0,6 R to the tip and from the blade trailing edge to avalue of 0,2 chord length.

3.4.2 Maximum forward blade force Ff

The maximum forward blade force Ff, in kN, is equal to:

• when D ≤ Dlimit :

• when D > Dlimit :

where:

Ff is to be applied as a uniform pressure distribution to anarea on the face (pressure) side of the blade for the follow-ing load cases (see Tab 3):

• Load case 3: on the blade face from 0,6 R to the tip andfrom the blade leading edge to a value of 0,5 chordlength

• Load case 5: a load equal to 60% Ff is to be appliedfrom 0,6 R to the tip and from the blade leading edge toa value of 0,2 chord length.

3.4.3 Maximum propeller ice torque applied to the propeller

Qmax is the maximum torque on a propeller due to ice-pro-peller interaction:

• when D ≤ Dlimit :

• when D > Dlimit :

where:

Dlimit = 1,8 Hice

3.4.4 Maximum blade spindle torque for CP-mechanism design Qsmax

The spindle torque Qsmax , in kN⋅m, around the spindle axisof the blade fitting is to be calculated for the load casesdescribed in [3.3.3].

These spindle torque values are not to be less than the fol-lowing default value, in kN⋅m:

Qsmax = 0,25 F c0,7

where:

F : Blade force, in kN⋅m, equal to Fb or Ff , which-ever has the greater absolute value.

3.4.5 Maximum propeller ice thrust (applied to the shaft at the location of the propeller)

The maximum propeller ice thrusts Tf and Tb , in kN, areequal to:

• forwards:

Tf = 1,1 Ff

• backwards:

Tb = 1,1 Fb

Qmax 105 1 dD----–

SqiceP0 7,

D---------

0 16, t0 7,

D-------

0 6,

nD( )0 17, D 3=

Qmax 202 1 dD----–

Sqice Hice1 1, P0 7,

D---------

0 16, t0 7,

D-------

0 6,

nD( )0 17, D1 9,=

Fb 9 5,– SiceEAR

Z-----------

0 3,

nD( )0 7, D 2=

Fb 66 Sice– EARZ-----------

0 3,

Hice1 4, nD( )0 7, D0 6,=

Ff 250 EARZ----------- D2=

Ff 500 EARZ----------- D 1

1 dD----–

------------------- Hice=

Dlimit2

1 dD----–

------------------- Hice=

Qmax 74 1 dD----–

P0 7,

D---------

0 16, t0 7,

D-------

0 6,

nD( )0 17, Sqice D3=

Qmax 141 1 dD----–

P0 7,

D---------

0 16, t0 7,

D-------

0 6,

nD( )0 17, Sqice D1 9, Hice1 1,=


NR 527, Sec 3

Table 3 : Load cases for ducted propeller

3.5 Design loads on propulsion line

3.5.1 Torque

The propeller ice torque excitation for shaft line dynamicanalysis is to be described by a sequence of blade impactswhich are of half sine shape and occur at the blade fre-quency or at twice the blade frequency (see Fig 1).

The torque due to a single blade ice impact as a function ofthe propeller rotation angle is then:

• when ϕ = 0°, ... , αi :

Q(ϕ) = Cq Qmax sin (ϕ (180/αi))

• when ϕ = αi , ... , 360°:

Q(ϕ) = 0

where parameters Cq and αi are given in Tab 4.

The total ice torque is obtained by summing the torque ofsingle blades taking into account the phase shift 360°/Z.

The number of propeller revolutions during a millingsequence is to be obtained with the following formula:

NQ = 2 Hice

The number of impacts is:• for blade order excitation: Z NQ

• for twice the blade order excitation: 2 Z NQ

Milling torque sequence duration is not valid for pullingbow propellers, which are subject to special consideration.

The response torque at any shaft component is to be ana-lysed considering excitation torque Q(ϕ) at the propeller,actual engine torque Qe and mass elastic system.

The design torque (Qr) of the shaft component is to be deter-mined by means of torsional vibration analysis of the pro-pulsion line. Calculations are to be carried out for allexcitation cases given above and the response is to beapplied on top of the mean hydrodynamic torque in bollardcondition at considered propeller rotational speed.

Load case N°

Force Loaded areaRight handed propeller blade

seen from back

1 Fb

Uniform pressure applied on the back of theblade (suction side) to an area from 0,6 R tothe tip and from the leading edge to 0,2 timesthe chord length

3 Ff

Uniform pressure applied on the blade face(pressure side) to an area from 0,6 R to the tipand from the leading edge to 0,5 times thechord length

560% of Ff or Fb

which one is greater

Uniform pressure applied on propeller face(pressure side) to an area from 0,6 R to the tipand from the trailing edge to 0,2 times thechord length

��

��

��

��

��

��


NR 527, Sec 3

Figure 1 : Shape of the propeller ice torque excitation for 45, 90, 135 degrees single blade impact sequencesand 45 degrees double blade impact sequence (two ice pieces) on a four bladed propeller

Table 4 : Parameters Cq and αi

3.5.2 Maximum response thrust Tr

The maximum thrust Tr along the propeller shaft line, in kN,is to be calculated with the formulae below. The factors 2,2and 1,5 take into account the dynamic magnification due toaxial vibration. Alternatively, the propeller thrust magnifica-tion factor may be calculated by dynamic analysis.• in forward direction: Tr = Tn + 2,2 Tf

• in backward direction: Tr = 1,5 Tb

where:Tn : Hydrodynamic propeller bollard thrust, in kN.

If Tn is not known, Tn is to be taken as given inTab 5

Tf , Tb : Maximum forward and backward propeller icethrusts, defined in [3.4.5].

3.5.3 Blade failure load for both open and nozzle propeller

The force is acting at 0,8 R in the weakest direction of theblade and at a spindle arm of 2/3 of the distance of axis ofblade rotation of leading and trailing edges, whichever isthe greater.

The blade failure load, in kN, is equal to:

where:

σref = 0,6 σ0,2 + 0,4 σu

Table 5 : Hydrodynamic propeller bollard thrust Tn

��

�

��

��

��

��

�

� ��

� ��

��

��

� ��

� ��

��

��

��

�

��

��

��

��

�

��

�

��

��

��

��

�

� ��

� ��

��

��

��

�

��

��

��

��

�

� ��

� ��

��

��

� � !�� " �

� � !�� " �

Torque excitation

Propeller-ice interaction

Cq αi

Case 1 single ice block 0,50 45



Case 4two ice blocks with 45° phase in rotation angle

0,50 45

Propeller type Tn , in kN

CP propellers (open) 1,25 T

(ducted) 1,10 T

FP propellers driven by

turbine or electric motor T

diesel engine (open) 0,85 T

diesel engine (ducted) 0,75 T

Fex0 3 c t2 σref,0 8 D, 2 r–-------------------------- 103=


NR 527, Sec 3

4 Design

4.1 Design principle

4.1.1 The strength of the propulsion line is to be designed:• for maximum loads in Article [3]• such that the plastic bending of a propeller blade shall

not cause damages in other propulsion line components• with sufficient fatigue strength.

4.2 Azimuth main propulsors

4.2.1 In addition to the above requirements, special con-sideration is to be given to the loading cases which areextraordinary for propulsion units when compared withconventional propellers. Estimation of the loading casesmust reflect the operational realities of the ship and thethrusters. In this respect, for example:• the loads caused by impacts of ice blocks on the propel-

ler hub of a pulling propeller, and• the loads due to thrusters operating in an oblique angle

to the flow,

are to be considered. The steering mechanism, the fitting ofthe unit and the body of the thruster are to be designed towithstand the loss of a blade without damage. The plasticbending of a blade is to be considered in the propellerblade position, which causes the maximum load on thestudied component.

4.3 Blade design

4.3.1 Maximum blade stressesThe blade stresses are to be calculated using the backwardand forward loads given in [3.3] and [3.4]. The stresses areto be calculated with traceable FE-analysis or other accept-able alternative method. The stresses on the blade are not toexceed the allowable stresses for the blade material givenbelow.

The calculated blade stress for the maximum ice load is tocomply with the following criterion:

σcalc < σall

where:

S = 1,5σref : Reference stress equal to:

σref = Min (0,7 σu ; 0,6 σ0,2 + 0,4 σu )

σ0,2 , σu : Representative values for the blade material.

4.3.2 Blade edge thicknessThe blade edge thicknesses ted and tip thickness ttip are to begreater than tedge given by the following formula:

where:x : Distance from the blade edge measured along

the cylindrical sections from the edge, to be

taken as 2,5% of chord length, without beingtaken greater than 45 mmIn the tip area (above 0,975 R radius) x is to betaken as 2,5% of 0,975 R section length and isto be measured perpendicularly to the edge,without being taken greater than 45 mm

S : Acceptance criteria:• for trailing edge: S = 2,5• for leading edge: S = 3,5• for tip: S = 5,0

pice : Ice pressure for leading edge and tip thickness,taken equal to 16 Mpa

σref : As defined in [4.3.1].The requirement for edge thickness has to be applied forleading edge and in case of reversible rotation open propel-lers also for trailing edge. Tip thickness refers to the maxi-mum measured thickness in the tip area above 0,975 Rradius. The edge thickness in the area between position ofmaximum tip thickness and edge thickness at 0,975 Rradius is to be interpolated between edge and tip thicknessvalue and smoothly distributed.

4.4 Prime movers

4.4.1 The main engine is to be capable of being started andrunning the propeller with the CP in full pitch.

4.4.2 Provisions are to be made for heating arrangementsto ensure ready starting of the cold emergency power unitsat an ambient temperature applicable to the additional classnotations POLAR CLASS or the service notations Ice-breaker.

4.4.3 Emergency power units are to be equipped with start-ing devices with a stored energy capability of at least threeconsecutive starts at the design temperature in [4.4.2]. Thesource of stored energy is to be protected to preclude criti-cal depletion by the automatic starting system, unless a sec-ond independent means of starting is provided. A secondsource of energy is to be provided for an additional threestarts within 30 minutes, unless manual starting can bedemonstrated to be effective.

5 Machinery fastening loading accelerations

5.1 General

5.1.1 Essential equipment and main propulsion machinerysupports are to be suitable for the accelerations as indicatedin [5.2]. Accelerations are to be considered acting inde-pendently.

5.2 Accelerations

5.2.1 Longitudinal impact accelerations aThe maximum longitudinal impact acceleration at any pointalong the hull girder, in m/s2, is equal to:

σallσref

S--------=

tedge x S Sice3 pice

σref

------------≥

a

FIB

Δui

-------= 1 1 γstem φ+( )tan, 7 HLui

------+


NR 527, Sec 3

5.2.2 Vertical impact acceleration av

The combined vertical impact acceleration av at any pointalong the hull girder, in m/s2, is equal to:

where:• Fx = 1,30 at FEui

• Fx = 0,20 at midship section

• Fx = 0,40 at AEui

• Fx = 1,30 at AEui for ships conducting ice breakingastern.

Intermediate values of Fx are to be interpolated linearly.

5.2.3 Transverse impact acceleration at

The combined transverse impact acceleration at at any pointalong hull girder, in m/s2, is equal to:

where:• Fx = 1,50 at FEui

• Fx = 0,25 at midship section

• Fx = 0,50 at AEui

• Fx = 1,50 at AEui for ships conducting ice breakingastern.

Intermediate values of Fx are to be interpolated linearly.

6 Auxiliary systems

6.1 General

6.1.1 Machinery is to be protected from the harmful effectsof ingestion or accumulation of ice or snow. Where contin-uous operation is necessary, means are to be provided topurge the system of accumulated ice or snow.

6.1.2 Means are to be provided to prevent damage due tofreezing, to tanks containing liquids.

6.1.3 Vent pipes, intake and discharge pipes and associ-ated systems are to be designed to prevent blockage due tofreezing or ice and snow accumulation.

7 Sea inlets and cooling water systems

7.1 General

7.1.1 Cooling water systems for machinery that are essen-tial for the propulsion and safety of the ship, including seachests inlets, are to be designed for the environmental con-ditions applicable for the additional class notations POLARCLASS and the service notations Icebreaker.

7.1.2 At least two sea chests are to be arranged as ice boxesfor the additional class notations POLAR CLASS 1 to 5inclusive and for the service notations Icebreaker 1 to 5inclusive. The calculated volume for each ice box is to be atleast 1 m3 for every 750 kW of the total installed power.

For the additional class notations POLAR CLASS 6 and 7 andfor the service notations Icebreaker 6 and 7, there is to be atleast one ice box, located preferably near the centreline.

7.1.3 Ice boxes are to be designed for an effective separa-tion of ice and venting of air.

7.1.4 Sea inlet valves are to be secured directly to the iceboxes. The valve is to be a full bore type.

7.1.5 Ice boxes and sea bays are to have vent pipes and areto have shut off valves connected direct to the shell.

7.1.6 Means are to be provided to prevent freezing of seabays, ice boxes, ship side valves and fittings above the loadwater line.

7.1.7 Efficient means are to be provided to re-circulatecooling seawater to the ice box. The total sectional area ofthe circulating pipes is not to be less than the area of thecooling water discharge pipe.

7.1.8 Detachable gratings or manholes are to be provided forice boxes. Manholes are to be located above the deepest loadline. Access is to be provided to the ice box from above.

7.1.9 Openings in ship sides for ice boxes are to be fittedwith gratings, or holes or slots in shell plates. The net areathrough these openings is to be not less than 5 times thearea of the inlet pipe. The diameter of holes and width ofslot in shell plating is to be not less than 20 mm. Gratings ofthe ice boxes are to be provided with a means of clearing.Clearing pipes are to be provided with screw-down typenon return valves.

8 Ballast tanks

8.1 General

8.1.1 Efficient means are to be provided to prevent freezingin fore and after peak tanks and wing tanks located abovethe water line and where otherwise found necessary.

9 Ventilation system

9.1 General

9.1.1 The air intakes for machinery and accommodationventilation are to be located on both sides of the ship.

9.1.2 Accommodation and ventilation air intakes are to beprovided with means of heating.

9.1.3 The temperature of inlet air provided to machineryfrom the air intakes is to be suitable for the safe operation ofthe machinery.

10 Alternative design

10.1 General

10.1.1 As an alternative, a comprehensive design studymay be submitted and may be requested to be validated byan agreed test programme.

av 2 5FIBFX

Δui

-------,=

at 3 FiFx

Δui

-------=


NR 527, Sec 4

SECTION 4 SHIPS OPERATING IN POLAR WATERS (POLARCAT)

1 General

1.1 Application

1.1.1 This Section applies to ships having one of the addi-tional service features POLAR CAT-A, POLAR CAT-B orPOLAR CAT-C.

1.1.2 This Section includes:

a) the requirements of the IMO International Code forShips Operating in Polar Waters (Polar Code), printed inItalic type when quoted in the Section; in the reproduc-tion of the Polar Code applicable for the purpose ofclassification, the word “Administration”, wherevermentioned, has been replaced by the word “Society”.Exceptions are indicated in [1.1.3].

b) the additional classification requirements of the Societyand the Society’s interpretations of the Polar Code,printed in regular font.

The requirements of this Section are cross-referenced to theapplicable Part, Chapter and paragraph of the Polar Code,as appropriate, under the wording “POLAR CODE REFER-ENCE”.

1.1.3 The following requirements of the Polar Code are notwithin the scope of classification:

• Part I-A Safety measures, Chapter 11 - Voyage planning

• Part I-A Safety measures, Chapter 12 - Manning andtraining

• Operational requirements of Part II-A Pollution preven-tion measures.

1.2 Definitions

1.2.1 Ship operating in low air temperature

POLAR CODE REFERENCE: Part I-A, Chapter 1, 1.2.12

Ship intended to operate in low air temperature means aship which is intended to undertake voyages to or throughareas where the lowest Mean Daily Low Temperature(MDLT) is below -10°C.

1.2.2 Mean Daily Low Temperature (MDLT)


Mean Daily Low Temperature (MDLT) means the meanvalue of the daily low temperature for each day of the yearover a minimum 10 year period. A data set acceptable tothe Society may be used if 10 years of data is not available.

Guidance instructions for determining MDLT:

a) determine the daily low temperature for each day for a10 year period,

b) determine the average of the values over the 10 yearperiod each day,

c) plot the daily averages over the year,

d) take the lowest of the averages for the season of opera-tion.

1.2.3 Polar Service Temperature


Polar Service Temperature (PST) means a temperature spec-ified for a ship which is intended to operate in low air tem-perature, which is to be set at least 10°C below the lowestMDLT for the intended area and season of operation inpolar waters.

1.2.4 Ship with the additional class notation COLD (H tDH , E tDE)

When the additional class notation COLD (H tDH , E tDE) isassigned to the ship, the temperature tDE and tDH are definedas follows:

• the lowest design external air temperature tDE , in °C, tobe considered for the equipment exposed to low airtemperature, is to be equal to the Polar Service Temper-ature (see [1.2.3])

• the lowest mean daily average air temperature tDH , in°C, to be considered for the hull exposed to low air tem-perature, is to be taken not more than 13°C higher thanthe Polar Service Temperature (see [1.2.3]).

1.3 Documents to be submitted

1.3.1 Plans and documents to be submitted for approval

The following plans and documents are to be submitted tothe Society for approval:

• hull plating and framing

• stability calculations in intact and damaged conditionswhen relevant

• machinery arrangement (particularly sea chest arrange-ment)

• winterization arrangement and systems

• sewage treatment plant arrangement when relevant.


NR 527, Sec 4

1.3.2 Documents to be submitted for informationThe following documents are to be submitted to the Societyfor information:

• the operating profile describing area and season ofoperation, ice conditions, temperatures (see [2.2.2])

• the operational assessment methodology and outcome(see [2])

• the Polar Water Operational Manual (PWOM) (see[3.1]).

2 Operational assessment

2.1 General

2.1.1 PurposePOLAR CODE REFERENCE: Part I-A, Chapter 1, 1.5

In order to establish procedures or operational limitations,an assessment of the ship and its equipment shall be carriedout, taking into consideration the following:

a) the anticipated range of operating and environmentalconditions, such as:

1) operation in low air temperature,

2) operation in ice

3) operation in high latitude

4) potential for abandonment onto ice or land

b) hazards, as listed in the Polar Code; and

c) additional hazards, if identified.

The operating profile, the methodology and the outcome ofthe operational assessment are reviewed by the Society inorder to issue the Polar Ship Certificate and to verify that allthe requirements of the Polar Code are fulfilled according tothe intended operations.

2.2 Methodology

2.2.1 PrinciplesThe methodology may be based on the following steps:

a) to define operating profile (see [2.2.2])

b) to identify relevant hazards (see [2.2.3]) and any otherhazards based on a review of the operating profile

c) to develop a model in order to analyse risks, consider-ing:

• development of accident scenarios

• probability of events in each accident scenario, and

• consequence of end states in each scenario

d) to assess risks and to determine acceptability:

• to estimate risk levels in accordance with theselected modelling approach, and

• to assess whether the risk levels are acceptable

e) in the event that risk levels determined in the previoussteps are considered to be too high: to identify currentor develop new risk control options that aim to achieveone or more of the following:

• to reduce the frequency of failures through betterdesign, procedures, training, etc.

• to mitigate the effect of failures in order to preventaccidents

• to limit the circumstances in which failures mayoccur, or

• to mitigate consequences of accidents

f) to incorporate risk control options for design, proce-dures, training and limitations, as applicable.

2.2.2 Operating profileThe operating profile is used to describe the expected envi-ronmental and operational conditions in the area where theship is intended to trade. The operating profile may bedefined on the following relevant information and availabledocumentation:

a) season and area of operation

b) ice charts covering the season and area and giving themost likely ice conditions

c) temperature data for the season and area, over at least10 years

d) operation with icebreaker escort

e) description of Search And Rescue (SAR) availability.

Table 1 : Outcome of the operational assessment

Item Main outcome Additional outcome

Ice class selection Ice class notation Equivalency procedure when relevant

Ice accretion is likely to occur yes / no −

Snow accumulation is likely to occur yes / no −

Slush ice or ice ingestion are likely to occur yes / no −

Operating in low air temperature yes / no Polar Service Temperature (PST)

Freezing temperatures are likely to occur yes / no −

Operating at high latitude yes / no −

Operating during extended periods of darkness yes / no −

Operating during extended periods of daylight yes / no −

Scenario of abandonment water / ice / land Maximum Estimated Time of Rescue (ETR)

Operating with icebreaker escort yes / no −


NR 527, Sec 4

2.2.3 Hazards

The hazards to be considered during the operational assess-ment may be taken as follows:

a) ice (sea ice regime, ice accretion, ice ingestion)

b) snow accumulation

c) low air and sea temperature

d) extended periods of darkness or daylight

e) high latitude

f) remoteness and possible lack of accurate and completehydrographic data and information

g) lack of ship crew experience in polar operations

h) lack of suitable emergency response equipment

i) rapidly changing and severe weather conditions

j) environmental impacts.

Additional hazards may be considered if relevant.

2.2.4 Outcome of the assessment

As an outcome of the operational assessment, the informa-tion to be provided to the Society are summarized in Tab 1.

3 Safety

3.1 Polar Water Operational Manual (PWOM)

3.1.1 General


In order to provide the Owner, operator, master and crewwith sufficient information regarding the ship's operationalcapabilities and limitations, to support their decision-mak-ing process, a Polar Water Operational Manual (PWOM)shall be carried on board.

3.1.2 Content of the PWOM

POLAR CODE REFERENCE: Part I-A, Chapter 2, 2.3.2 and2.3.3

A table of contents is given as a guidance in App 1.

The PWOM shall contain the methodology used to deter-mine capabilities and limitations in ice.

In order to avoid encountering conditions that exceed theship’s capabilities, the PWOM shall include or refer to spe-cific risk-based procedures in normal operations for the fol-lowing:

a) voyage planning to avoid ice and/or temperatures thatexceed the ship's design capabilities or limitations;

b) arrangements for receiving forecasts of the environmen-tal conditions;

c) means of addressing any limitations of the hydrographic,meteorological and navigational information available;

d) operation of equipment; and

e) implementation of special measures to maintain equip-ment and system functionality under low temperatures,topside icing and the presence of sea ice, as applicable.

In the event of incidents in polar waters, the PWOM shallinclude risk-based procedures to be followed for:

a) contacting emergency response providers for salvage,search and rescue (SAR), spill response, etc., as applica-ble; and

b) in the case of ship with an ice class notation or servicenotation Icebreaker, procedures for maintaining lifesupport and ship integrity in the event of prolongedentrapment by ice.

The PWOM shall include risk-based procedures to be fol-lowed for measures to be taken in the event of encounteringice and/or temperatures which exceed the ship's designcapabilities or limitations.

The PWOM shall include risk-based procedures for monitor-ing and maintaining safety during operations in ice, as appli-cable, including any requirements for escort operations oricebreaker assistance. Different operational limitations mayapply depending on whether the ship is operating inde-pendently or with icebreaker escort. Where appropriate, thePWOM should specify both options.

3.2 Ship structure

3.2.1 Materials of exposed structures


For a ship operating in low air temperature and having theadditional class notation COLD (H tDH , E tDE), the materialsfor weather and sea exposed structural members and formembers attached to the weather and sea exposed shellplating are to comply with the applicable requirements of PtE, Ch 10, Sec 11 of the Rules for Steel Ships.

When a ship is granted with an additional class notationPOLAR CLASS or a service notation Icebreaker, in case thematerial grades in Sec 2 and those of the additional classnotation COLD (H tDH , E tDE) differ, the higher materialgrade is to be selected.

3.2.2 Hull scantlings


When a ship is granted with the additional service featurePOLAR CAT-A, the hull scantlings are to comply with atleast the requirements of Sec 2, as applicable to the addi-tional class notation POLAR CLASS 5 or the service featureIcebreaker 5.

When a ship is granted with the additional service featurePOLAR CAT-B, the hull scantlings are to comply with atleast the requirements of Sec 2 as applicable to the addi-tional class notation POLAR CLASS 7 or the service featureIcebreaker 7.

The additional service feature POLAR CAT-B may begranted to a ship with the hull scantlings complying withthe additional class notation ICE CLASS IA SUPER or ICECLASS IA.


NR 527, Sec 4

When a ship is granted with the additional service featurePOLAR CAT-C, the hull scantlings are to comply with theassigned ice class, as applicable.

When, according to the outcome of the operational assess-ment, ice strengthening is not required, typically for openwater, the additional service feature POLAR CAT-C is to begranted.

3.3 Stability

3.3.1 Intact conditions


When, according to the outcome of the operational assess-ment, the ship is operating in areas and during periodswhere ice accretion is likely to occur, the stability in intactconditions is to take into account the weight of ice accre-tion on the full length of the ship, as follows:

a) 30 kg/m2 on exposed weather decks and gangways;

b) 7,5 kg/m2 for the projected lateral area of each side ofthe ship above the water plane; and

c) the projected lateral area of discontinuous surfaces ofrail, sundry booms, spars (except masts) and rigging ofship having no sails and the projected lateral area ofother small objects shall be computed by increasing thetotal projected area of continuous surfaces by 5% andthe static moments of this area by 10%.

Ships operating in areas and during periods where iceaccretion is likely to occur shall be:

a) designed to minimize the accretion of ice; and

b) equipped with means for removing ice equipped withsuch means for removing ice as the Society may require;for example, electrical and pneumatic devices, and/orspecial tools such as axes or wooden clubs for removingice from bulwarks, rails and erections.

Note 1: When the additional class notation COLD DI is assigned,the requirements above are fulfilled.

The PWOM is to include information about icing allowanceused in the stability calculations and is to refer the appropri-ate measures to be taken to ensure that the ice accretiondoes not exceed this allowance (see Chapter 5 in thePWOM given in App 1, Tab 3).

3.3.2 Damaged conditions


The residual stability after ice damage is to be calculated fora ship having the additional service feature POLAR CAT-Aor POLAR CAT-B.

When a probabilistic approach is required, the probabilityfactor of survival after flooding si is to be taken equal to 1,0for all the loading conditions used to calculate the attainedsubdivision index.

When a deterministic approach is required, the residual sta-bility criteria are to be complied with for each loading con-dition.

The ice damage extents to be assumed for both probabilisticand deterministic approaches, regardless of the SDS nota-tion, are defined as follows:

a) the longitudinal extent is 4,5% of the upper ice water-line length if centred forward of the maximum breadthon the upper ice waterline, and 1,5% of upper icewaterline length otherwise, and shall be assumed at anylongitudinal position along the ship's length;

b) the transverse penetration extent is 760 mm, measurednormal to the shell over the full extent of the damage;and

c) the vertical extent is the lesser of 20% of the upper icewaterline draught or the longitudinal extent, and shall beassumed at any vertical position between the keel and120% of the upper ice waterline draught.

Note 1: When the additional class notation COLD (H tDH , E tDE) isassigned, the damage stability is to take into account the weight ofice accretion as specified in the additional class notation.

3.4 Watertight and weathertight integrity

3.4.1 General


When, according to the outcome of the operational assess-ment, the ship is operating in areas and during periodswhere ice accretion is likely to occur, means are to be pro-vided to remove or prevent ice and snow accretion aroundhatches and doors.

Note 1: When the additional class notation COLD DI is assigned,the requirements above are fulfilled.

3.4.2 Ships with the additional class notation COLD (H tDH , E tDE) operating in low air temperature


For a ship operating in low air temperature and having theadditional class notation COLD (H tDH , E tDE), all the clos-ing appliances and doors relevant to the watertight andweathertight integrity are to comply with the applicablerequirements of Pt E, Ch 10, Sec 11 of the Rules for SteelShips.

3.5 Machinery installations

3.5.1 General


When, according to the outcome of the operational assess-ment, the ship is operating in areas and during periodswhere ice accretion and/or snow accumulation and/or slushice conditions or freezing are likely to occur, the followingapplies:

a) machinery installations and associated equipment are tobe protected against the effect of ice accretion and/orsnow accumulation, ice ingestion from sea water, freez-ing and increased viscosity of liquids, seawater intaketemperature and snow ingestion;

b) working liquids shall be maintained in a viscosity rangethat ensures operation of the machinery; and


NR 527, Sec 4

c) seawater supplies for machinery systems shall bedesigned to prevent ingestion of ice (Refer to MSC/Circ.504, Guidance on design and construction of sea inletsunder slush ice conditions), or otherwise arranged toensure functionality.

Note 1: When the additional class notation COLD DI is assigned,requirements a) and b) above are fulfilled.



For a ship operating in low air temperature and having theadditional class notation COLD (H tDH , E tDE), the machin-ery installations are to comply with the applicable require-ments of Pt E, Ch 10, Sec 11 of the Rules for Steel Ships.

3.5.3 Propulsion and steering equipment


When a ship is granted with the additional service featurePOLAR CAT-A, the scantlings of propeller blades, propul-sion line, steering equipment and other appendages are tocomply with at least the requirements of Sec 3, as applica-ble to the additional class notation POLAR CLASS 5 or theservice feature Icebreaker 5.

When a ship is granted with the additional service featurePOLAR CAT-B, the scantlings of propeller blades, propul-sion line, steering equipment and other appendages are tocomply with at least the requirements of Sec 3, as applica-ble to the additional class notation POLAR CLASS 7 or theservice feature Icebreaker 7.

The additional service feature POLAR CAT-B may begranted to a ship having the scantlings of propeller blades,propulsion line, steering equipment and other appendagesin compliance with the additional class notation ICE CLASSIA SUPER or ICE CLASS IA.

When a ship is granted with the additional service featurePOLAR CAT-C, the scantlings of propeller blades, propul-sion line, steering equipment and other appendages are tocomply with the assigned ice class, if applicable.

3.6 Fire safety and protection

3.6.1 General

POLAR CODE REFERENCE: Part I-A, Chapter 7, 7.3.1 and7.3.2

When, according to the outcome of the operational assess-ment, the ship is operating in areas and during periodswhere ice accretion and/or snow accumulation and/or slushice conditions or freezing are likely to occur, the fire safetysystems and appliances are to comply with the followingrequirements:

a) isolating and pressure/vacuum valves in exposed loca-tions are to be protected from ice accretion and remainaccessible at all time;

b) fire pumps including emergency fire pumps, water mistand water spray pumps are to be located in compart-ments maintained above freezing;

c) the fire main shall be arranged so that exposed sectionscan be isolated and means of draining of exposed sec-tions shall be provided. Fire hoses and nozzles need notbe connected to the fire main at all times, and may bestored in protected locations near the hydrants;

d) firefighter's outfits shall be stored in warm locations onthe ship; and

e) where fixed water-based fire-fighting systems are locatedin a space separate from the main fire pumps and usetheir own independent sea suction, this sea suction shallbe also capable of being cleared of ice accumulation.

Note 1: When the additional class notation COLD DI is assigned,requirements a) to d) above are fulfilled.



For a ship operating in low air temperature and having theadditional class notation COLD (H tDH , E tDE), the exposedfire safety systems and appliances are to comply with theapplicable requirements of Pt E, Ch 10, Sec 11 of the Rulesfor Steel Ships.

3.7 Life-saving appliances

3.7.1 Escape


When, according to the outcome of the operational assess-ment, the ship is operating in areas and during periodswhere ice accretion is likely to occur, means shall be pro-vided to remove or prevent ice and snow accretion fromescape routes, muster stations, embarkation areas, survivalcraft, its launching appliances and access to survival craft.

Exposed escape routes shall be arranged so as not to hinderpassage by persons wearing suitable polar clothing.

When a ship is operating in low air temperature, adequacyof embarkation arrangements shall be assessed, having fullregard to any effect of persons wearing additional polarclothing.

3.7.2 EvacuationPOLAR CODE REFERENCE: Part I-A, Chapter 8, 8.3.2

Ships shall have means to ensure safe evacuation of per-sons, including safe deployment of survival equipment,when operating in ice-covered waters, or directly onto theice, as applicable.

When means to ensure safe evacuation are requesting anadditional source of power, this source shall be able tooperate independently of the ship's main source of power.

3.7.3 SurvivalPOLAR CODE REFERENCE: Part I-A, Chapter 8, 8.3.3

For a ship assigned with the service notation Passenger shipor Ro-ro passenger ship, a proper sized immersion suit or athermal protective aid shall be provided for each person onboard.

For any ship where immersion suits are required, they shallbe of the insulated type.


NR 527, Sec 4

When, according to the outcome of the operational assess-ment, the ship is operating in extended periods of darkness,searchlights suitable for continuous use to facilitate identifi-cation of ice shall be provided for each lifeboat.

No lifeboat shall be of any type other than partially ortotally enclosed type.

Appropriate survival resources, which address both individ-ual (personal survival equipment) and shared (group sur-vival equipment) needs, shall be provided, as follows:

a) life-saving appliances and group survival equipment thatprovide effective protection against direct wind chill forall persons on board;

b) personal survival equipment in combination with life-saving appliances or group survival equipment that pro-vide sufficient thermal insulation to maintain the coretemperature of persons; and

c) personal survival equipment that provide sufficient pro-tection to prevent frostbite of all extremities.

When, according to the outcome of the operational assess-ment, a potential of abandonment onto ice or land is identi-fied, the following applies:

a) group survival equipment shall be carried, unless anequivalent level of functionality for survival is providedby the ship's normal life-saving appliances;

b) when required, personal and group survival equipmentsufficient for 110% of the persons on board shall bestowed in easily accessible locations, as close as practi-cal to the muster or embarkation stations; and

c) containers for group survival equipment shall bedesigned to be easily movable over the ice and be float-able.

When, according to the outcome of the operational assess-ment, the need to carry personal and group survival equip-ment is identified, means shall be identified of ensuring thatthis equipment is accessible following abandonment.

When carried in addition to persons, in the survival craft,the survival craft and launching appliances shall have suffi-cient capacity to accommodate the additional survivalequipment.

Passengers shall be instructed in the use of the personal sur-vival equipment and the action to take in an emergency.

The crew shall be trained in the use of the personal survivalequipment and group survival equipment.

Adequate emergency rations shall be provided, for the max-imum expected time of rescue (ETR).

3.8 Safety of navigation

3.8.1 Nautical informationPOLAR CODE REFERENCE: Part I-A, Chapter 9, 9.3.1

Ships shall have means of receiving and displaying currentinformation on ice conditions in the area of operation.

3.8.2 Navigational equipment functionalityPOLAR CODE REFERENCE: Part I-A, Chapter 9, 9.3.2

Ships shall comply with SOLAS regulation V/22.1.9.4, irre-spective of the size and, depending on the bridge configura-tion, have a clear view astern.

For a ship granted with an ice class or one of the servicefeatures Icebreaker, the following applies:

a) either two independent echo-sounding devices or oneecho-sounding device with two separate independenttransducers shall be provided

b) where the required equipment has sensors that projectbelow the hull, such sensors shall be protected againstice

c) when the ship is granted with the additional service fea-ture POLAR CAT-A or POLAR CAT-B, the bridge wingsshall be enclosed or designed to protect navigationalequipment and operating personnel.

When, according to the outcome of the operational assess-ment, the ship is operating in areas and during periodswhere ice accretion is likely to occur, means to prevent theaccumulation of ice on antennas required for navigationand communication shall be provided.

Ships shall have two non-magnetic means to determine anddisplay their heading. Both means shall be independent andshall be connected to the ship's main and emergencysource of power.

When, according to the outcome of the operational assess-ment, the ship is proceeding to latitudes over 80 degrees,the ship shall be fitted with at least one GNSS compass orequivalent, which shall be connected to the ship's main andemergency source of power.

3.8.3 Additional navigational equipment


When, according to the outcome of the operational assess-ment:

• the ship is not operating in areas with 24 hours daylight,the ship shall be equipped with two remotely rotatable,narrow-beam search lights controllable from the bridgeto provide lighting over an arc of 360 degrees, or othermeans to visually detect ice

• the ship is involved in operations with an icebreakerescort, the ship shall be equipped with a manually initi-ated flashing red light visible from astern to indicatewhen the ship is stopped. This light shall have a range ofvisibility of at least two nautical miles, and the horizon-tal and vertical arcs of visibility shall be conform to thestern light specifications required by the InternationalRegulations for Preventing Collisions at Sea.

3.9 Communication

3.9.1 Ship communication


Communication equipment on board shall have the capabil-ities for ship-to-ship and ship-to-shore communication, tak-ing into account the limitations of communications systemsin high latitudes and the anticipated low temperature.

Note 1: When a ship is navigating above latitudes of 76°N or 76°S,the GMDSS equipment is to be compliant with the requirements forsea areas A1 to A4 (refer to COMSAR/Circ. 32 Harmonization ofGMDSS requirements for radio installations on board SOLASships).


NR 527, Sec 4

Two-way on-scene and Search And Rescue (SAR) coordina-tion communication capability in ship shall include:

a) voice and/or data communications with relevant rescuecoordination centres; and

b) equipment for voice communications with aircraft on121,5 MHz and 123,1 MHz.

The communication equipment shall provide for two-wayvoice and data communication with a TeleMedical Assist-ance Service (TMAS).

A ship with one of the additional service notations Ice-breaker shall be equipped with a sound signalling systemmounted to face astern to indicate escort and emergencymanoeuvres to following ships as described in the Interna-tional Code of Signals.

3.9.2 Survival craft and rescue boat communication capabilities


When a ship is operating in low air temperature, all rescueboats and lifeboats, whenever released for evacuation,shall:

a) for distress alerting, carry one device for transmittingship to shore alerts,

b) in order to be located, carry one device for transmittingsignals for location,

c) for on-scene communications, carry one device fortransmitting and receiving on-scene communications.

Note 1: Requirements above are fulfilled when, on each rescueboat and lifeboat, the following communication devices are car-ried:

• one equipment of EPIRB type for ship to shore communications

• one equipment of SART type for transmitting signals for loca-tion

• one equipment of VHF type (portable or fixed) for on-scenecommunications.

When a ship is operating in low air temperature, all othersurvival craft shall:

a) in order to be located, carry one device for transmittingsignals for location,

b) for on-scene communications, carry one device fortransmitting and receiving on-scene communications.

Note 2: Requirements above are fulfilled when the following com-munication devices are stored on board in order to be carried oneach survival craft:

• one equipment of SART type for transmitting signals for loca-tion

• one equipment of VHF type for on-scene communications.

Recognizing the limitations arising from battery life, proce-dures shall be developed and implemented such that man-datory communication equipment for use in survival craft,including liferafts, and rescue boats are available for opera-tion during the maximum expected time of rescue.

4 Pollution prevention

4.1 Pollution by oil

4.1.1 ApplicationPOLAR CODE REFERENCE: Part II-A, Chapter 1, 1.2

The requirements of [4.1.2] to [4.1.5] apply only to shipsgranted with the additional service feature POLAR CAT-A orPOLAR CAT-B.

4.1.2 Fuel oil tanksPOLAR CODE REFERENCE: Part II-A, Chapter 1, 1.2.1

A ship with an aggregate oil fuel capacity of less than600 m3 is to be assigned with the additional class notationPROTECTED FO TANKS, as defined in Part A of the Rulesfor Steel Ships.

4.1.3 Cargo oil tanks of oil tankers less than 5000 tons deadweight

POLAR CODE REFERENCE: Part II-A, Chapter 1, 1.2.3

A ship assigned with one of the following service notations:

• Oil tanker

• FLS tanker

• Combination carrier/OBO ESP

• Combination carrier/OOC ESP,

and with a deadweight less than 5000 tons, is to have theentire cargo length protected with double bottom tanks,wing tanks or spaces other than cargo and fuel oil tanks,arranged in accordance with the applicable requirementsgiven in Pt D, Ch 7, Sec 2, [3.2.4] of the Rules for SteelShips.

4.1.4 Cargo tanks of ships other than oil tankersPOLAR CODE REFERENCE: Part II-A, Chapter 1, 1.2.2

A ship not assigned with one of the service notations listedin [4.1.3] shall have all cargo tanks constructed and utilizedto carry oil separated from the outer shell by a distance ofnot less than 0,76 m.

4.1.5 Oil residue tanksPOLAR CODE REFERENCE: Part II-A, Chapter 1, 1.2.4

All oil residue (sludge) tanks and oily bilge water holdingtanks shall be separated from the outer shell by a distanceof not less than 0,76 m. This requirement does not apply tosmall tanks with a maximum individual capacity not greaterthan 30 m3.

4.2 Pollution by sewage

4.2.1 Sewage treatment plantPOLAR CODE REFERENCE: Part II-A, Chapter 4, 4.2.1

A sewage treatment plant is not required when the ship hasa sufficient onboard storage capacity for liquid effluentallowing the fully loaded ship to operate without discharg-ing any sewage substances into the sea during the expectedtime of operation. Note 1: When the additional class notation NDO-x days is assigned,requirement above is fulfilled and a sewage treatment plant is notrequired.


NR 527, Sec 4

When the ship operates in areas of ice concentrations lessthan 1/10 and is assigned with:

• the service notation Passenger ship or Ro-ro passengership, and/or

• the additional service feature POLAR CAT-A or POLARCAT-B,

the discharge of sewage into the sea is allowed only with anapproved sewage treatment plant certified by the Society to

meet the operational requirements in regulation either 9.1.1or 9.2.1 of MARPOL Annex IV.

When the ship operates in areas of ice concentrationsexceeding 1/10 for extended periods of time, the dischargeof sewage into the sea is allowed only for a ship having theadditional service feature POLAR CAT-A or POLAR CAT-Band using an approved sewage treatment plant certified bythe Society to meet the operational requirements in regula-tion either 9.1.1 or 9.2.1 of MARPOL Annex IV.


NR 527, App 1

APPENDIX 1 POLAR WATER OPERATIONAL MANUAL (PWOM)

1 General

1.1 Application

1.1.1 The Polar Water Operational Manual (PWOM) isintended to address all aspects of operations. When appro-priate information, procedures or plans exist elsewhere in aship's documentation, the PWOM itself does not need toreplicate this material but may, instead, cross-reference therelevant document.

As a guidance, a table of contents is given in this Appendix.

Not every section will be applicable to every polar ship. Forinstance POLAR CAT-C ships that undertake occasional orlimit polar voyages will not need to have procedures for sit-uations with a very low probability of occurrence.

Noting an aspect as ‘not applicable’ also indicates that thisaspect has been considered and not merely omitted.

1.2 Table of contents

1.2.1 A detailed table of contents with guidances are givenin Tab 2 to Tab 5 for each division of the PWOM listed inTab 1.

Table 1 : Contents of PWOM

Table 2 : Contents for operational capabilities and limitations

Division Title

1 Operational capabilities and limitations

2 Ship operations

3 Risk management

4 Joint operations

1 - OPERATIONAL CAPABILITIES AND LIMITATIONS

Chapter 1 - Operation in ice

1.1 - Operator guidance for safe operation

The PWOM should establish the means by which decisions as to whether ice conditionsexceed the ship's design limits should be made, taking into account the operational limitationson the Polar Ship Certificate. An appropriate decision support system, such as the Canada'sArctic Ice Regime Shipping System, and/or the Russian Ice Certificate as described in the Rulesof Navigation on the water area of the Northern Sea Route, can be used (1).Bridge personnel should be trained in the proper use of the system to be utilized. For ships thatwill operate only in ice-free waters, procedures to ensure that will keep the ship from encoun-tering ice should be established.

1.2 - Icebreaking capabilities The PWOM should provide information on the ice conditions in which the ship can beexpected to make continuous progress. This may be drawn, for example from numerical anal-ysis, model test or from ice trials. Information on the influence of ice strength for new ordecayed ice and of snow cover may be included.

1.3 - Manoeuvring in ice No guidance.

1.4 - Special features Where applicable, the PWOM should include the results of any equivalency analyses made todetermine Polar Ship category/ice class. The manual should also provide information on theuse of any specialized systems fitted to assist in ice operations.

Chapter 2 - Operation in low air temperatures

2.1 - System design The PWOM should list all ship systems susceptible to damage or loss of functionality by expo-sure to low temperatures, and the measures to be adopted to avoid malfunction.

Chapter 3 - Communication navigation capabilities in high latitudes

The PWOM should identify any restrictions to operational effectiveness of communications and navigational equipment that mayresult from operating in high latitudes.

Chapter 4 - Voyage duration

The PWOM should provide information on any limitations on ship endurance such as fuel tankage, fresh water capacity, provision stores,etc. This will normally only be a significant consideration for smaller ships, or for ships planning to spend extended periods in ice.

(1) Guidance on methodologies for assessing operational capabilities and limitations in ice (POLARIS) as described in IMO Circu-lar MSC.1/Circ.1519, can also be used.


NR 527, App 1

Table 3 : Contents for ship operations

2 - SHIP OPERATIONS

Chapter 1 - Strategic planning

Assumptions used in conducting the analyses referred to below should be included in the Manual.

1.1 - Avoidance of hazardous ice For ships operating frequently in polar waters, the PWOM should provide information withrespect to periods during which the ship should be able to operate for intended areas ofoperation. Areas that pose particular problems, e.g. chokepoints, ridging, as well as worstrecorded ice conditions should be noted. Where the available information is limited or ofuncertain quality, this should be recognized and noted as a risk for voyage planning.

1.2 - Avoidance of hazardous temperatures

For ships operating frequently in polar waters, the PWOM should provide information withrespect to, the daily mean daily low temperature as well as the minimum recorded tempera-ture for each of the days during the intended operating period. Where the available informa-tion is limited or of uncertain quality, this should be recognized as a risk for voyage planning.

1.3 - Voyage duration and endurance

Procedures to establish requirements for supplies should be established, and appropriate safetylevels for safety margins determined taking into account various scenarios, e.g. slower thanexpected steaming, course alterations, adverse ice conditions, places of refuge and access toprovisions. Sources for and availability of fuel types should be established, taking into accountlong lead times required for deliveries.

1.4 - Human resources management

The PWOM should provide guidance for the human resources management, taking intoaccount the anticipated ice conditions and requirements for ice navigation, increased levels ofwatch keeping, hours of rest, fatigue and a process that ensures that these requirements will bemet.

Chapter 2 - Arrangements for receiving forecasts of environmental conditions

The PWOM should set out the means and frequency for provision of ice and weather information. Where a ship is intended tooperate in or in the presence of ice, the manual should set out when weather and ice information is required and the format for theinformation.When available, the information should include both global and localized forecasts that will identify weather and ice patterns/regimes that could expose the ship to adverse conditions.The frequency of updates should provide enough advance notice that the ship can take refuge or use other methods of avoiding thehazard if the conditions are forecast to exceed its capabilities.The PWOM may include use of a land-based support information provider an effective method of sorting through available informa-tion, thereby providing the ship only with information that is relevant, reducing demands on the ship's communications systems. Themanual may also indicate instances in which additional images should be obtained and analysed, as well as where such additionalinformation may be obtained.

2.1 - Ice information The PWOM should include or refer to guidance on how radar should be used to identify icefloes, how to tune the radar to be most effective, instructions on how to interpret radar images,etc. If other technologies are to be used to provide ice information, their use should also bedescribed.

2.2 - Meteorological information No guidance.

Chapter 3 - Verification of hydrographic, meteorological and navigational information

The PWOM should provide guidance on the use of hydrographic information.

Chapter 4 - Operation of Special Equipment

4.1 - Navigation systems No guidance.

4.2 - Communication systems No guidance.

Chapter 5 - Procedures to maintain equipment and system functionality

5.1 - Icing prevention and de-icing

The PWOM should provide guidance on how to prevent or mitigate icing by operationalmeans, how to monitor and assess ice accretion, how to conduct de-icing using equipmentavailable on the ship, and how to maintain the safety of the ship and its crew during all ofthese aspects of the operation.

5.2 - Operation of seawater systems

The PWOM should provide guidance on how to monitor, prevent or mitigate ice ingestion byseawater systems when operating in ice or in low water temperatures. This may includerecirculation, use of low rather than high suctions, etc.

5.3 - Procedures for low temperature operations

The PWOM should provide guidance on maintaining and monitoring any systems and equip-ment that are required to be kept active in order to ensure functionality; e.g. by trace heatingor continuous working fluid circulation.


NR 527, App 1

Table 4 : Contents for risk management

Table 5 : Contents for joint operations

3 - RISK MANAGEMENT

Chapter 1 - Risk mitigation in limiting environmental condition

1.1 - Measures to be considered in adverse ice conditions

The PWOM should contain guidance for the use of low speeds in the presence of hazardousice. Procedures should also be set for enhanced watchkeeping and lookout manning insituations with high risks from ice, e.g. in proximity to icebergs, operation at night, and othersituations of low visibility. When possibilities for contact with hazardous ice exist, proceduresshould address regular monitoring, e.g. soundings/inspections of compartments and tanksbelow the waterline.

1.2 - Measures to be considered in adverse temperature conditions

The PWOM should contain guidance on operational restrictions in the event that temperaturesbelow the ships polar service temperature are encountered or forecast. Thesemay include delaying the ship, postponing the conduct of certain types of operation, usingtemporary heating, and other risk mitigation measures.

Chapter 2 - Emergency response

In general, where the possibility of encountering low air temperatures, sea ice, and other hazards is present, the PWOM shouldprovide guidance on procedures that will increase the effectiveness of emergency response measures.

2.1 - Damage control the PWOM should consider damage control measures arrangements for emergency transfer ofliquids and access to tanks and spaces during salvage operations.

2.2 - Fire-fighting No guidance.

2.3 - Escape and evacuation Where supplementary or specialized lifesaving equipment is carried to address the possibilitiesof prolonged durations prior to rescue, abandonment onto ice or adjacent land, or otheraspects specific to polar operations, the PWOM should contain guidance on the use of theequipment and provision for appropriate training and drills.

Chapter 3 - Coordination with emergency response services

3.1 - Ship emergency response The PWOM should include procedures to be followed in preparing for a voyage and in theevent of an incident arising.

3.2 - Salvage The PWOM should include procedures to be followed in preparing for a voyage and in theevent of an incident arising.

3.3 - Search and rescue The PWOM should contain information on identifying relevant Rescue Coordination Centresfor any intended routes, and should require that contact information and procedures beverified and updated as required as part of any voyage plan.

Chapter 4 - Procedures for maintaining life support and ship integrity in the event of prolonged entrapment by ice

Where any ship incorporates special features to mitigate safety or environmental risks due to prolonged entrapment by ice, thePWOM should provide information on how these are to be set up and operated. This may include, for example, adding additionalequipment to be run from emergency switchboards, draining systems at risk of damage through freezing, isolating parts of HVACsystems, etc.

4.1 - System configuration No guidance.

4.2 - System operation No guidance.

4 - JOINT OPERATIONS

Chapter 1 - Escorted operations

The PWOM should contain or reference information on the rules and procedures set out by coastal States who require or offericebreaking escort services. The manual should also emphasize the need for the master to take account of the ship's limitations inagreeing on the conduct of escort operations.

Chapter 2 - Convoy operations No guidance.


NR 527, App 2


APPENDIX 2 METHOD FOR DETERMINING EQUIVALENT ICE CLASS

1 General

1.1 Application

1.1.1 This Appendix is a guidance intended to help in thedetermination of equivalency with standards acceptable bythe Society. The methodology is consistent with the guide-lines for the approval of alternatives and equivalents as pro-vided for in various IMO instruments (MSC.1/Circ.1455),while it allows the use of a simplified approach.

1.2 Principles

1.2.1 The basic approach for considering equivalency forPOLAR CAT-A and POLAR CAT-B ships can be the same forboth new and existing ships. It involves comparing other iceclasses to the Polar Classes. For ice classes under POLARCAT-C, additional information on comparisons of strength-ening levels is available (refer to the annex to HELCOMRecommendation 25/7 Safety of Winter Navigation in theBaltic Sea Area). The responsibility for generating the equiv-alency request and supporting information required shouldrest with the Owner/operator. Review/approval of anyequivalency request should be undertaken by the Society.

1.2.2 The scope of a simplified equivalency assessment isexpected to be limited to:

a) materials selection

b) structural strength of the hull

c) propulsion machinery.

1.2.3 If there is not full and direct compliance, then anequivalent level of risk may be accepted in accordance witha guidance provided by the Society. An increase in theprobability of an event can be balanced by a reduction in itsconsequences. Alternatively, a reduction in probabilitycould potentially allow acceptance of more serious conse-quences. Using a hull area example, a local shortfall instrength level or material grade could be accepted if theinternal compartment is a void space, for which a localdamage will not put the overall safety of the ship at risk orlead to any release of pollutants.

1.2.4 For existing ships, service experience can help in therisk assessment. As an example, for an existing ship with arecord of polar ice operations, a shortfall in the extent of theice belt (hull areas) may be acceptable if there is no recordof damage to the deficient area; i.e. a ship, that would gen-erally meet POLAR CLASS 5 requirements but in limitedareas is only POLAR CLASS 7, could still be considered as aPOLAR CAT-A ship. In all such cases, the ship documenta-tion should make clear the nature and the scope of any defi-ciencies.

1.3 Process of assessment

1.3.1 Steps of assessment

The process includes the following steps of assessment:

a) selection of the target POLAR CLASS for equivalency

b) comparison of the materials used in the design with theminimum requirements under the target POLAR CLASS;identification of any shortfalls, and

c) comparison of the strength levels of hull and machinerycomponents design with the requirements under the tar-get POLAR CLASS; quantification of the levels of com-pliance.

1.3.2 Additional steps of assessment

Where gaps in compliance are identified in the previoussteps, additional steps should be necessary to demonstrateequivalency, as outlined below:

a) to identify any risk mitigation measures incorporated inthe design of the ship (in addition to the requirements ofthe Polar Code and the target POLAR CLASS)

b) to provide, where applicable, documentation of serviceexperience of the existing ships, in conditions relevantto the target POLAR CLASS for equivalency, and

c) to undertake an assessment, taking into account infor-mation from all the previous steps, as applicable, andon the principles outlined from [1.2.1] to [1.2.4].

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