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,

ICE SEA MAN S HIP

by

George Q. Parnell Master Mariner

of the Company of Master Mariners of Canada Member of The Nautical Institute

Author: Capt. Geo. Q. Parnell MNI 43 Lacey Green Drive Kirkland (Montreal), Que. Canada H9H 3H6

Tel. (514)-695-5652 (Off.) 695-2928 (Res.)

Telex 05-821762

INTRODUCTION

From the age of the wind-driven Arctic whalers and early expedition vessels to the present age of nuclear icebreakers and modern ships strengthened against fee and equi.pped with powerful engines, operating a ship in ice has always been a specialised field, quite unlike any other. It calls for knowledge of and expertise in ice matters and for the highest degree of ice seamanship, even if occasionally this aspect has been ignored or forgotten - what can happen to ships in ice is best illustrated by case histories of shipping losses, records of ship repair yards and claims paid by insurance underwriters. In addition, it requires the possession of what is known in the trade as the "ice sense", the "feel" or the instinct for ice. None of these qualities can be acquired in a single day, and the inexperienced ice navigator would be wise to listen to the advice given to him by the ice pilot if one is employed in his vessel.

Hhen operating in waters where ice is present SPEED is a most vital factor as will be demonstrated in chapters which follow. The general rule is also to avoid ice if possible rather than to battle with it. In the case of a ship under way this means deviating from the original intended tracks, always looking for open water or easier ice conditions and going round the ice, not through it. Experience has demonstrated clearly that although by doing so the distance is increased it is actually quicker - and safer, because contact with ice is eliminated or minimised. It is not always possible of course to avoid ice, and sooner or later the navigator will be faced with the prospect of going through it if conditions allow. How this can be done with safety in mind is discussed in this manual.

In the case of a vessel alongside in a harbour where there is current or tide and drift ice is present, if such drift ice becomes heavy nothing will hold the vessel, not even a multitude of mooring lines, insurance wires and anchor chains secured ashore, and the same will apply to a vessel at anchor. The recommended practice in such cases is to move the vessel to a safe berth or anchorage where she can shelter from the moving ice.

As can be seen from the above, when operating in ice the safety aspect cannot be emphasised too strongly, but it must also be pointed out at the same time that the navigator who is too cautious in ice might cause endless delays resulting sometimes in cancellations of voyages and losses of earnings for the shipowner - the navigation season in ice regions like the Arctic can be very short and while passages always have to be made SAFELY they must also be made SPEEDILY (on the other hand, the reckless or inexperienced navigator might also wreck his ship in ice in a blind effort to maintain his schedules, as has happened in the past). Furthermore, it might be just vital for a vessel to pass through a certain area quickly to avoid rapidly deteriorating ice conditions and becoming trapped in ice, therefore any unnecessary delay of one day or even a few hours in some cases might easily result in much longer delays with increased risks later.

ii

If a definition of a good ice navigator were to be attempted, the following could be suggested: "a good ice navigator is one who knows how to combine safety of operations in ice with passages that are also made speedily and in good time".

Let the above brief remark3 and the notes and illustrations which follow serve as a useful guide - and as a warning too, in which case their inclusion in this introduction will be more than justified.

G.Q.P.

Montreal, Quebec

July 1986

iii

CONTENTS

Introduction

Page

i

PART 1: ICE

General Terms and Definitions 1

Types of Floating Ice 2

Sea Ice 3

A Brief Note on the Formation of Sea Ice 4

Disintegration of Sea Ice 5

6

7

8

9

17 under Different Conditions of Light at

18

19

20 Ice Cake, Brash Ice, Pancake Ice

21

22

23

24

25

26

27

Glacier Ice

Birth of an Iceberg

A Note on the Stability of Icebergs

Ice Identification

Visual Detection of Icebergs and Other Ice

Pack Ice

Ice Floes

Other Ice Terms in General Use

Fast Ice, Ice Shelf

Ice Islands

Tabular Bergs

Ice Ridge, Hummocked Ice, Rafted Ice

Ice Strips, Ice Patch, Floebergs

Pressure in Ice

Ice Summary

Night

iv

PART 2: ICE SEAMANSHIP

Basic General Safety Rules 30

Know your Ice 33

Stopping in Ice 33

FIG. 1 Looking for and utilising leads 34 and easier ice conditions

2Force of Impact Displacement x Speed 35

FIG 2: A clear message to all Ice 36 Navigators

waterline in ice

a vessel strengthened against ice

unavoidable

available ice charts

swinging in patches of open water or in leads

when negotiating pack ice

Ballasting and Trimming for Ice 37

Avoiding and Negotiating Ice 38

FIG. 3 The importance of ship's d)'aft and 40

FIG. 4 Drawing showing the "ice bf~lt" in 41

FIG. 5 When passage through ice becomes 42

FIGo 6 Avoiding large ice floes in the pack 43

FIG. 7 Recommended safe track based on 44

FIG. 8 Approaching ice 45

FIG. 9 Danger of damage to ship's side when 46

FIG.I0 Danger of the stern swinging 47

FIG.II Effect of ice conditions Oel speed 48

FIG.12 Keep well clear of icebergs 49

v

FIG.13 Ac tion to avoid icebergs and loose 50 ice

shore leads

correct procedure in curves

distance from icebreaker (1)

distance from icebreaker (2)

pressure in ice

running into ice dislodged by icebreaker

emergency procedure

there is current or tide

charts

FIG.14 Passing icebergs 51

FIG.15 Danger when proceeding thrclUgh 52

FIG.16 Going astern in ice 53

FIG.17 When beset (1) 54

FIG.18 When beset (2) 55

FIG.19 Ramming and backing in ice 56

FIG.20 Following an icebreaker in ice ­ 57

FIG.21 Following an icebreaker in ice (2) 58

FIG.22 Following an icebreaker in ice (3) 59

FIG.23 Following astern of icebreaker ­ 60

FIG.24 Following astern of icebre~ker ­ 61

FIG.25 Following an icebreaker in ice - no 62

FIG.26 Following an icebreaker - danger of 63

FIG.27 Operating astern of icebreaker ­ 64

FIG.28 Sheltering from drift ice when 65

FIG.29 Unsafe berths in icebound ports 66

FIG.31 The correct use of Canadian Arctic 68

vi

FIG~32 Glacier ice as radar target 69

screen

appear on the radar screen

RADAR, ICE AND SAFETY

through waters where ice is present

FIG.33 Ice as it may appear on the radar 70

FIG.34 Ice and ship targets as they may 71

FIG.35 General safety rules on passage 74

Useful Hints and Observations: 75

1. Anchoring in ice 75

2. Towing in ice 75

3. Braking effect of the rudder 75

4. Lights and signals for vessels 76 beset

5. Abandoning ship in ice 76

6. Freezing of ballast and fresh 76 water tanks

7. Freezing of fresh water tanks in 76 lifeboats

8. Additional fuel and stores 77

90 Searchlight 77

10. Recommended miscellaneous 78 useful items and equipment

Recommended Reading 79

Index 81

PART 1: ICE

General Terms and Definitions

1

ICE: General Terms and Definitions

Ice is frozen water, or water in solid state.

The freezing point of water depends on salinity i.e. the salt content of the water. The greater the salinity, the lower the freezing point.

Fresh water freezes at 00 C. (32 0 F.):

Sea water with salinity of 35 parts per thousand or corresponding specific gravity of 1.025 freezes at -1.9 0 C. (28.6 0 F.).

(It is to be noted that the MELTING point of ice is the same as the freezing point of the water from which it originated assuming the same salt content).

The physics and chemistry of ice is a highly complex matter presently subject of much field and laboratory studies and research. Briefly, there are various forms of ice in nature, the mariner being mainly concerned with FLOATING ice, and this type of ice is discussed and illustrated further in this chapter.

Floating Ice Sea level

j ThicknessDraft

The relationship between Specific gravity of ice will draft and height of ice depend on type of ice and its above sea level will de­ salt and air content. For pure pend entirely on the type fresh water ice it is said to and the age of ice. As be 0.916 or 0.917, and for a general indication, the icebergs about 0.9. An average draft could be anything of 0.9 for ice generally could from 6 times to as low as be considered in order for all 1 or 2 times the height practical purposes.

2

TYPES OF FLOATING ICE

__________ River Ice

A. FRESH WATER ICE

~Lake Ice

~New Ice

?---,young Ice

B. SEA ICE ~ --First Year Ice

~Old Ice

~ICebergS

C. GLACIER ICE Bergy Bits

(Ice of land origin) ~ Growlers

3

SEA ICE

Sea ice is ice formed by the freezing of sea water. As the freezing process continues sea ice grows in thickness, gradually loses its salt and by doing so becomes harder with age. It is usually classified according to its age or stage of development as shown below:

(1). New Ice: A general term for recently formed ice

(2). Young Ice: Sea ice in tran­sition between New Ice and Fi rst Year Ice

(3). First Year Ice: Sea ice of not more than one year's growth developing from young ice

(4). Old Ice: Sea ice which has survived at least one summer's melt

Frazil ice Grease ice Slush Shuga Thickness Ice rind to 10 em Nilas Pancake ice

___ Grey Ice 10 - 15 em 10 - 30 em

""Grey-white Ice 15 - 30 em

Thin First Year 30 - 70 em ("White" Ice)/.

30 em - 2 m -- Medium First Year 70 - 120 em

""ThiCk First Year over 120 em

Second Year Ice: Ice which has survived the

~ first summer. 2 m or more(Up

more

to 3

thick

m or

\

thick

Multi-year Ice: lIce which has survived at least two summers. 3 m or more thick

4

A BRIEF NOTE ON THE FORMATION OF SEA ICE

c=--:---:::-,' . '. "\

; .; . '" .............. -0"" #- _ .

Stage 1.

Sea water freezes at about _2 0 C. depending on salinity. At certain stage of freezing brine is trapped in small pockets in ice. At this stage this newly-formed ice is relatively soft and pliable.

Stage 2.

As the new ice is subjected to further freezing in winter salt gradually drains out through vertical channel­like openings linking the pockets of brine. The rate at which the salt is lost will depend on temperature.

Stage 3.

After about one year or more depending on temperature all salt is lost and the ice becomes pure fresh water ice. This ice gradually grows in thickness and after two more summers may grow to an average thickness of 3.5 m or more. At this stage it is extremely hard, has the characteristic blue-green colour, can stop even a powerful icebreaker and must be treated with respect by the navigator.

5

MELTING AND DISINTEGRATION OF SEA ICE

The process of melting and disintegration of sea ice is more complex than its formation and growth, and will depend on the salt content and the age of the ice. The simplified diagrams below illustrate some of the stages.

Puddles or pools

\ ~"'-V-',.d'n4( '.?~~.../

~

I \. I

I

As summer progresses,1 I \ I

II \ surface of the ice and

I I I. t ,I \

) \ . I ,I

I

the snow cover melt ~, I ,

: forming puddles or pools\ " _.--~,-, ....... ,.-... ,,\, .. .,,,..... ,,- ........ ........ "-.. of fresh or nearly fresh water, and these increase steadily in size.

Thaw holes

The puddles absorb more radiation from the sun than the adjoining ice surface and develop into thaw holes through the ice. This results in the gradual break-up of the ice.

Honeycombed appearance of some of the forms of sea ice in the final stages of

.... I -~ (. ... ' :r.J-/')e=~ ... " ......_. ,,... \ 9 ~" 'I. '/' "::.r;;, '" "\.._;.'- dt!fi"' .... •" '--'~ --.-;' ? . " ~ ..... , I -.- \<U I melting and disintegration .

~'" ,"F. <7V-,...,....... .S; ','lPI /''' ", -In7 ,.. -<I .,/.;/!II".& , .. .. -----.- II I ..".... ~ ..,1;>'1 I J

J ,.... - ~~ V" ~;." -\: '", .,,'" L:(fY ~ (IA "'......... Au .- J ' ·IP.." \-. -) & ' ':;;.oK,,' r.·;' A'. (k . ­

'" IJ".t".. 1 ,. 7·.-', .. ,r.:Y' '- ­1/ ~ .••.••. :...' ..... ,.','",-, ."

t;:J·_f.l . '~ ~

6

GLACIER ICE (Sometimes called GLACIAL Ice)

Glacier ice is ice originating from glaciers

--l- .--"

t n

~11:'i

Over 5

I I ..... ~ .,.'

m

\ \ \/'

-.- -

I

I " I ,,

I, ,..- ICEBERG !,", \ I

, . , . t.. 4. " ...... to , ..... , ., .". ... . .... .. --. " '

... ... ~ '-. . .. _.... - ".'...,:.........

Area 100 - 300 sq.m

., ;

.' I " '. BERGY BIT

'..-, ... /

'.\,.

• # ,f ' •• ' ,.. ..

tl-Rj?

Height less than 1 m Area 20 sq.m

_ll--~T:=J~__----f.~~.,__ ,r~ ". ~ ,.~ .~

'If .'~..." "

'''. '-1." .'

GROWLER

7

BIRTH OF AN ICEBERG (Calved from a GLACIER)

13reqk Movement

Stage L

"-....

1/' ~ 1l::?!~;vaDz~.. .'!~ .......... fo .... "" ............. .... r ...' \ , -'. .... .~ ......

\ \ \ ~ ,

\ \

.... '.. ....

'.... Se ... .... ... ..... - ..11 13 01'1' 11

.... -...... 0

Stage 2.

\ - ~ Iceberg I ,'7-r,-., ,}IITf!!!:!: ~ hi~ORE 'J!T!lllTllTTr/ C=~~l ........t I\c!"!. ~ ,- A .... r"'?-,'III/!,.

, -'.f .,' \ .' i ...... .. ..... \ .I .J\\ '.,. .: . .: . \ '... ..." .. ·"".4'"

\ \

\ \. ,

"', ',,- SeA. 13

........ h ........ , 01'1'ON ..... -.....

'\

- GLACIER -r

8

A NOTE ON THE STABILITY OF ICEBERGS

(This refers to icebergs floating down with the Labrador Current from the Baffin Bay area towards Newfoundland).

-=:"7 ;==­" " , G ~

" . \,, , • B ,,,i

\ ';

\. ..._' ..... ,- ........-. .-- .... '"

=:=t G:==• • Z I { • 1 "'. BZ " .... .

\......~ • • ill " _ ' ......; _Oo .. ,

Broadly speaking, the centre of gravity of an iceberg (G) is usually very close to and just above the centre of buoyancy (B). This results in relatively poor stability .

Due to continuous process of erosion and melting, particularly of the submerged portion, the shape of an iceberg is continually changing. When the iceberg becomes top-heavy and G and B move to G, and B, respectively,the iceberg will capsize.

After capsizing, G and B assume new locations GZand B and the process

Zwill continue until the iceberg completely melts or disintegrates after reaching the warmer waters of the Atlantic.

NOTE: this is yet another reason why ICEBERGS SHOULD NOT BE APPROACHED TOO CLOSELY , as theoretically, they are liable to capsize at any time. Records of some of the early Arctic explorers indicate that sometimes even a rifle shot might activate the capsizing process, the forces of buoyancy and gravity being so delicately balanced.

9

ICE IDENTIFICATION

Fresh Water Ice

~sealceType

-------- Glacier Ice

Thickness ~-:?:\ Thickness increasing with age as freezing continues until it

/, reaches maximum dependir ", .... " ...~._ ... , ..-.....'. 0

on locality

Snow cover (white)

Colour (bare ice)

_ ro2?>n.~ ./,,;,><-f...~ /'• :s:. wP~

'\#= ~:

t. o

"

: I' :

Colour of sea ice changes with age

", .......... , , . oo • , .

Hardness - Varies with type of ice. Hardness of sea ice increases with age and with fall in temperature below freezing. In the Arctic, after surviving one or two summers or longer sea ice becomes very hard and dangerous to shipping.

Concentration - Concentration is the amount of ice cover in relation to the area of water in which the ice floats. It is measured in tenths: 1/10 (10%) to 10/10 (100%)

10

ICE IDENTIFICATION

Ice Type

A. FRESH WATER ICE

B. SEA ICE

(1) • New Ice:

Frazil ice

Grease ice

Slush

Shuga

Ice rind

Nilas

Thickness to 10 cm

General Colour and

Appearance

White, crystal­like where bare. Identified by locality rather than appearance, e.g. St. Lawrence River above Quebec or the Great Lakes

Newly-formed ice gives the sea a soupy, oily or matt appearance

Characteristics of Practical Importance to the Mariner

Very hard ice, danger­ous to shipping when thick, its hard­ness for all practical purposes the same as glacier ice or old sea ice, and little affected by age.

This type of ice is relatively soft and pliable in comparison with fresh water ice or old sea ice, will not normally constitute any danger to the hull of a modern steel vessel except small craft of light construction (although it might block engine cooling water intakes of a vessel which has no ice class)

I ce Type

B. SEA ICE (1) . New Ice

(Contd) •

Pancake Ice to 10 cm

(2) • Young Ice 10-30 cm

Grey ice 10-15 cm

Grey-white 15-30 cm

General Colour and

Appearance

~::r-:~_ --:~='='d~"'b'Q.~ ,..".~

'1::>"" .·O.""'~~

Approximately circular in shape, 0.3 to 3 m across in size, with raised rims due to pieces rubbing together. Colour white or grey-white

Dark grey or light grey in colour, becoming whiter with age

]]

Characteristics of Practical Importance to the Mariner

A type of New Ice (see previous note)

Still containing some salt and relatively soft, but now growing thicker and gradually becoming harder. Its effect on ships will depend on type, power, ice class and concen­tration

12

Ice Type

B. SEA ICE (Contd.)

(3) • First Year Ice 30 cm to 2 m

Thin Fi rst Year Ice ( "White" Ice) 30-70 cm

Medium Fi rst Year Ice

70-120 cm

Thick First Year Ice over 120 cm

General Colour and

Appearance

see below

Generally white or milky-white in colour

This type of ice gradually changes colour as it becomes older and acquires a green or greenish tint after about one year depend­ing on temperatures

Characteristics of Practical Importance to the Mariner

Although this ice may not be as hard as OLD ice, it can neverthe­less be a serious obstacle to navigation when of certain thickness and concentration. Many ships have sustained hull and propeller damage in this type of ice (e.g. in the Gulf of St. Lawrence in winter). This ice must therefore be treated with respect. When rafted or ridged it can be a serious obstacle even to powerful icebreakers, and should never be under-estimated.

NOTE: the term "White" Ice is a Canadian term commonly used in the Gulf of St. Lawrence.

13

Ice Type

B. SEA ICE (Contd.)

(4) • Old Ice 3 m or more

Second Year Ice

2 m or more

Mul ti-year Ice

3 m or more

General Colour and

Appearance

All the old ice has a green or greenish tint changing to blue-green or intense blue with age as in the case of multi-year ice where bare

Characteristics of Practical Importance to the Mariner

The characteristic green-blue or blue colour of this ice must act as a useful warning to the ice navigator. This type of ice is EXTREMELY HARD and very dangerous to shipping, not excluding icebreakers, especially the very hard multi-year ice. For all practical purposes it can be con­sidered to be of the same hardness as floating STEEL-REINFORCED CONCRETE. Striking a large piece of this type of ice would have the same effect as striking a solid concrete dock wall. Even at a very slow speed the consequences could be disastrous.

14

General Colour Characteristics of and Practical Interest

Ice Type Appearance to the Mariner

c. GLACIER ICE Opaque white or For all practical (Sometimes flat white on purposes the hard­called the surface, ness of this ice is GLACIAL green-blue or the same as multi­ICE) intense blue year ice and just as

where bare. dangerous to shipping. (See previous Note). It appears in the form of icebergs, bergy bits and growlers,

Height of which the notorious over 5 m \ GROWLER is the most

-.4 \. ,,/~ dangerous particularly, ~ "

, • at night or in Iceberg

, i

r reduced visibilityII

I i

,,I

~

I

undetectablebecause it is

by practically

radar/

......-.__ .. - _... ~ .....~,." .. , when there is even slight sea running.

Height 1 to 5 m

Bergy Bi t

I, I

~

'\ \

.. ~ ~---

" , \ .. J

/­-

Height less than 1 m

Growler

./ \.. ,'-,.......

15

ICE IDENTIFICATION: General Note

(1). The various colours of ice as described in the above ice identification table are not intended as an infallible guide and should not be interpreted too literally bearing in mind that they refer to the colour of bare ice and that sometimes the colours might appear different to different observers.

(2). Furthermore, all ice is generally white in appearance but under certain conditions of light at night might look distinctly black. This phenomenon is illustrated in the drawing on the page following the end of this note.

(3). In the Arctic, however, any ice that looks vaguely blue-green or blue could without any doubt be glacial ice or old ice in one form or another, and if the navigator was not quite sure about the exact colour he would be wise not to contemplate this matter too long and assume for safety's sake that the ice is HARD ice and take action accordingly. After all, if his ship collides with an ice floe 3 1/2 metres thick and the size of two football fields it will hardly matter whether the floe was blue-green or blue - the result is likely to be just as devastating.

(4). In any event, after a snowfall all ice looks white and can be very difficult to identify. In the Arctic this invariably takes place towards the end of the summer season, and with limited hours of daylight and much reduced visibility can lead to potentially dangerous situations.

16

_:e ahead of the vessel MUST be identified before the vessel can proceed, ~~J operating under such conditions calls for high degree of ice :: Yl.petence.

17

Moon astern, iceberg ahead. Can be detect­ed visually if sharp lookout kept.

§:~~~~~".t===: . '-­

Moon astern, ice ahead. Reasonably well visi­ble, but only at short range if sharp lookout kept.

Moon ahead, iceberg ahead. Barely visible and diffi­cult to detect - looks black and blends with the night ­very dangerous.

-:3

Moon ahead, ice ahead. May appear as black strips blend­ing with other dark patches on the horizon and difficult to see. If ice is present under such conditions, stop and wait for daylight before proceeding.

Visual detection of icebergs and other ice under different conditions of light at night (assl~ing clear night and good visibility).

18

PACK ICE: the term Pack Ice refers generally to any accumulation of sea ice other than fast ice

Concentration:

o to 1/10

OPEN WATER

.~

1/10 to 3/10

VERY OPEN PACK

4/10 to 6/10

OPEN PACK

7/10 to 9/10

CLOSE PACK

CONSOLIDATED PACK 10/10 Floes frozen together

COMPACT PACK 10/10 No water visible

9/10 to 10/10VERY CLOSE PACK

19

ICE FLOES

A floe is a relatively flat piece of floating ice usually described as 20 m or more across. Floes can be classified according to size as illustrated below:

t Small floes: 20 to 100 m across

~:.--:-. - . ~-:---.~.~" ;-". - --a ... .'" \ ..' t, ',- ~, I

:. ~. •. .. i••••• ••u .... 'i. , ••• " ; ,'1 ~ •••••••• 'f • '" •• ,0 , ........ '" •• tI•• t

Medium floes: 100 to 500 m across

-:*"7' ,.. ..";:'-... -::<: ... .. .. ~............. ~~

.... ,"-, ", .f .. t <1 1 •••••••••••••••••••••••• -.1

Big floes: 500 m to 2 km across

-, ­.... ~....-::- c::-::z ~ ..... - ::;>~~---~ ~---

, : tI o

., ,.. ......... •• i •• •• • • t ••••••••••••: It _ ..................... ••••••• .,.1

! Vast floes: 2 to 10 km

~~-:-:r ....... .-c _ :::-::>: tiC -­F~--:'7 ';"'...-...... -. -- ........ - - ~,

'., .•..• t, It '" 11" <I' 00 ',.~ " ............... • It , • " .., " .. " " •••••

Giant floes: over 10 km (5 miles) across

& ~ .. - - -.'.-- __ . --.7 ... - ." ..".... .. .." "1- "h"".

!. II·· 0 • ,t •.• "~"'."""'" 4 If" I ·' .t , •• ,.1-0 <"'" -. -0 1

I

20

OTHER ICE TERMS IN GENERAL USE

Floes are smaller than 20 m across

ICE CAKE

Fragments of ice not more than 2 m across

BRASH ICE

New ice, approximately circular, about 0.3 m to 3.0 m across

PANCAKE ICE

21

FAST ICE: sea ice attached to the shore

Shore +.

"--.~==~~ __ .f. _ .._ ;'1,-;\......~ ...... .... ~ )~"..""..~ - . j

",., , ...... II ...... .~ • ••• '" '" ". .J

,)t. _/'" ,~;;'N'"'. 7;'" , /)

~~:;';;j7,jf' ;~~-.,~~77':??;;1»' I' ';I'~,-;;nI' '1'1' "r'" "'77)7 r r"

ICE SHELF: fast ice more than 2 m thick above sea level

t

~ ...-~ t"7 -~ .."...

);..................o' • _ ..

~ ~tV ~

22

ICE ISLANDS

, T

... ~ "S. -.::.::r-.-.........._~ _.,..;.~". -----..-----------~~~---:::L.

,. • "", r •• '-..... •• ..",. .. !l

i, t 30-50 m i

1 1... . , ..... • • ' • • * • " • I) " I. '. , • ••'" ~ •, • '-, ••• t' , f\l .' ,~ , •• , • ..".. '" .... " •• I ••• e •• •

Ice islands: a rare form of tabular bergs found only in the Arctic Ocean. About 5 m above sea level and some 30 to 50 m in thickness, area from a few thousand square m to about 500 square km or more. Are said to have "ribbed" appearance when seen from the air. Drift with sea ice at an average rate of 1 to 3 miles per day. Have been used by scientists as floating stations for periods of up to several years.

23

TABULAR BERGS

t {'

"'"'" (-. ~'-

\

30 m

",/

..... -" . 1\

1

•I f,,,,, •, J

{' •\ } 170 m\, f ~.,,, ,f

f 1, \,•,, ,f" \.. .-" ... __ - il • -. ....... - _ ........

_ _, __ .. ' .. 0-_ .... .....­

Tabular bergs are flat-topped and rectangular in shape, originate mainly from ice shelves and are commonly seen in the Antarctic where they can be of very large sizes, some reported as nearly 100 miles in length. Can also be found in the Arctic.

24

ICE RIDGE

!.. ~A ,,'" ,/ (-'- ~.' ..... ~, ..... ...... ~ .... -.. ••••• I' '\' ~.l· ' .. ~~-, .... ".~.'

'. f' · ,..~"'1' LI.~ t .... ,ll t '.' ..) ,.. , KEEL

... ... \\. i

til

tlKeels" may extend as much as 50 m below sea level

HUMMOCKED ICE

RAFTED ICE

..\ ....... .,. ..-4lI .. ,,.."" ,.....~~'~ • • ••-:.:.-,. ,'At .",,-: ,,;...... ·.t'•• f •••• ~ .• 't., ',.'.'

Common in newly-formed sea ice

25

..~;';;;O;~':'..;).':.ro~_·::"-.o:?l';"""'=-· ­...........:1_ ::-¥,...~,.- .-..~.;s--.

_. _. _ 0 ,~ .......

--::ii'~ 0 ;""'='.' ~'.I' ~ _ _._.0 _

1~~·~"t','t:;"~Ib~J~·"" -..di' ',_J6_.

,,­ ~,,~ ...... *'

A long narrow area of pack ice about 1 km

,- or less in width composed of small fragments of ice

ICE STRIPS

., .. ,D_fI'fg •

,,'0 ., . ­~~ ........-::..:'- An area of pack ice~ -'':;.:--'''~_ ... ~....(- - .... ~ .,r-' ~~

less than 10 k"m~.. ..~.. ~'"----=~t:=- .. ~r.l""--..."..,-~...- ::::.- ~ ­ (5 miles) across

ICE PATCH

o

aL, FLOEBERGI

/"\~)~~~~ ~ '.~ - ,'I .(A •• f~.".' 7· - "" ....... , f.::::;.

.., ..... .~ . ..\. a ' ~'\ " ' ••• 0 ,. ~ /" _ ~l I. :

, "

'.....''." ".._~' ..,.J

A floeberg is a massive piece of sea ice compo'sed of hummocked ice frozen together, thickness up to 5 m above sea level.

26

PRESSURE IN ICE (Ice "Under Pressure")

(J c::::;o~o ~

r' ~C'" (] 0 ~: ~/!J c/ ~I 0 n

Shore No wind

, ' , J : I '..... " )e••••• I' --II' ,. J

Open pack, no pressure. Passage through such ice can be made with reasonable ease and safety during day­light hours in good visibility depending on type of ice and vessel's ice class.

Due to wind action the open pack now becomes very close pack or consolidated or compact pack with ice hummocking and ridging, and floes freezing together. In this state it could be impassable even by powerful icebreakers.

27

ICE SUHMARY

(1). Ice MOVES. Under the influence of wind and current it is in an almost perpetual state of MOVEMENT - pack ice mainly under the influence of wind. Thus ice conditions in a given area are constantly CHANGING. With a change of wind the ice situation can completely change, sometimes virtually within hours. Thus very close pack can become open or very open pack, and conversely very open pack can become an impassable very close pack ice with ice under pressure. The experienced ice navigator constantly watches for changes in ice conditions and utilises them to his best advantage. When caught in heavy drifting ice the ship will be virtually at the mercy of the ice and will drift with it and go wherever the ice will take her. In the proximity of the shore, this can lead to potentially dangerous situations.

(2). Ice can be very HARD, and therefore dangerous to shipping. The hardness of sea ice increases with age and with fall in temperature, and in the Arctic the sea ice which has survived one or two summers or more becomes a very tough material, practically as hard as steel. Fresh water ice does not change much with age and is also very HARD, and the navigators whose ships operate in such areas as the St. Lawrence River in winter or in the Baltic (almost fresh water ice) should be fully aware of this fact.

(3). Ice FUSES when temperature falls below freezing. Thus an area composed of a number of separate ice floes and other loose fragments of ice which normally would be easily negotiated can turn quickly into one SOLID MASS of ice and pose serious problems even for icebreakers. The experienced ice navigator knows this and acts accordingly.

(4). After a SNOWFALL ice in the pack can be ve'ry difficult to identify. This calls for utmost caution and experience when passage through such ice is made.

(5). Ice is SELDOM UNIFORM - usualiy there couid be different types of ice in the pack. Thus for example, when negotiating at full speed what may seem like thin ice or some other form of light ice for miles on end, the navigator would be wise, especially in the Arctic, to be always on the lookout for floes or fragments of hard ice that could be interspersed with the light ice, more often than not under snow cover. In the Arctic the floes or fragments could be hard, multi-year ice; in the Gulf or in the estuary of the St. Lavrrence River they could be batture floes. Both must be avoided.

28

(6). When under PRESSURE pack ice is much more difficult to negotiate than when the pressure is off, an.d as a general rule depending on circrnnstances, passage through ice under pressure should normally be avoided.

(7). There are different TYPES of ice depending on hardness, thickness, floe size and concentration. Before proceeding through ice it must be fully identified. This can only be done visually.

dIliSNVWV3S 381 : Z .LlIVer

30

---------,

ICE SEAMANSHIP: BASIC GENERAL SAFETY RULES

(1) "Know your ice before you go through it". In other words) before attempting any passage through ice it is vitally important that the ice is identified as to: Type

Thickness Hardness Floe size Concentration

This identification must be made VISUALLY, and of course requires good knowledge of ice and experience. No instrument can do it.

(2) At night or in reduced visibility when passing through areas where ice is present, particularly hard ice or ice floes, speed must be reduced or vessel stopped until visibility improves and the navigator can see and identify ice ahead of the ship. This is NORMAL PROCEDURE.

(3) Force of Impact varies as 2Speed

or 2 Force of Impact varies as Displacement x Speed

This law of physics, vital to the ice navigator because of the effect of speed as well as displacement when contact with ice is made, deserves to be engraved in gold letters on the bridge of every ship operating in ice. If the TITANIC had only reduced speed that fateful night in 1912, the tragedy which followed could have been avoided.

31

(4) Any vessel operating in ice should be so ballasted and trimmed that the propeller tips and the rudder are as deep as possible even if this means carrying additional ballast not normally carried, provided of course that it is practical and safe to do so. If the vessel is reinforced against ice, ideally the draft and trim should be such that all contact with ice would be confined to the "ice belt" which forms part of the hull. As a general rule, ships handle much better in ice when loaded than when light.

(5) Ice must always be avoided if there is an alternative as a safety as well as time-saving measure, even if this means large alterations of course and deviation from the original intended route.

(6) When, due to the extent of the ice cover, ice cannot be avoided and passage through ice becomes inevitable if the vessel is to reach her destination, the following factors must be fully taken into consideration as a matter of course before any long passage or operations in ice generally are attempted;

1. type of ice; 2. time of the year, weather and temperature; 3. area of operation; 4. vessel's ice class in relation to the type of ice expected; 5. state of hull, machinery and equipment, and quantity or

bunkers and stores left; 6. draft and depth of water over the propeller tips and the

rudder; 7. ice experience of the person in charge on the oridge.

32

(7) Unscheduled contact with ice: if, for some reason, collision with ice or with an iceberg suddenly becomes inevitable, try to manoeuvre the vessel if time permits so as to strike the ice squarely with the bow which is the vessel's strongest point, rather than with the ship's side which is much more vulnerable to damage. This wou~d of course apply to all collision cases generally, but it would be of special significance to a vessel operating in ice because the woint of impact would be most likely at or below the waterline. (As an' example, it has been calculated that if the TITANIC had struck the iceberg squarely with the bow instead of altering course at th~ last minute and side-swiping it and gashing her side from forward to aft below the waterline as a result, the vessel would have sustain~d heavy bow damage but would not have sunk).

The above basic general safety rules can now be discussed in more detail.

33

DISCUSSION

KNOW YOUR ICE

Once ice has been identified appropriate action is taken. For instance, if the ice turns out to be thin new ice passage through it can be made at full speed following the original intended route. If the ice is thick first year ice or old ice which cannot be negotiated considering the ice class of the vessel, the navigator will be faced with the following alternatives:

1. Stop and wait till conditions improve with the change of wind/tide;

2. Stop and wait until an icebreaker is available;

3. In the absence of any ice charts or latest ice reports, sail along the edgl~ of the ice and look for leads or areas where ice conditions are better and where entry can be safely made. This situation is illustrated in Fig. 1. It will require some patience as it may be necessary to sail along the ice edge for many miles before a suitable point of entry can be found. (Clearly, this is one occasion when the feel for ice or the "ice sense u combined with experience will be indispensable).

STOPPING IN ICE

The constant alterations of course and speed for hours if not for days on end with frequent long stoppages may seem strange to the average deep-sea navigator, however~ all this is part and parcel of the daily life of a ship operating in ieee The rule is simple: if you are in ice and the visibility is poor and you cannot see what is ahead of you, you must stop and wait till visibility improves.

34

d TrackIntende

Actual Track

5

Miles

.. leads anFIG. 1 oking for and utilis1ng d easier La d-tions.ice con 1

35

t--__ splacement ~~d2 ]F_o_r_c_e_O_f_I_m_p_a_c_t_~_D_l_·

The implications of this rule are as follows:

1. Vessel's speed it affects the force of im

is pact.

a MOST VITAL factor when operating in ice Using unity for convenience:

as

Speed in

Knots

Force of

Impact

1 1 2 4 3 9 4 16 5 25

10 100 15 225

Thus, in the case of a vessel striking heavy ice at 4 knots the force of impact would be sixteen times as or at 15 knots 225 times what it was at the speed of one knot. The consequences of this can be well imagined.

2. A large vessel moving at an excessive speed will cause more damage to herself when striking heavy ice than a small vessel at the same velocity (because of the displacement factor in this case).

3. It is far more dangerous for a large vessel to proceed at an excessive speed at night or in reduced visibility through ice-infested waters than for a smaller vessel b{~cause of the difference in stopping distances.

36

2 I~rce of Impact Displacement x Speed J

R.M.S. TITANIC - 1912 A fine ship lost - over 1500 people drowned

I

/; /

:'''. ..;.;. ':) ::.:"1

-II ..

'--.'­ ~J ~;;::

/ ....:..:..-_­,,/ .... ­

I "... I ... ,

II

\J . (/ fiI

Probable shape of the iceberg IJ

t _I ....... _. ---".-)l I, J,

I J

,I' (

TI1e TITANIC sunk mainly because of excessive speed in waters where icebergs and pack ice were present.

\

.~ ~ :)

0:. 'I -=­

FIG. 2 A clear message to all ice navigators

37

BALLASTING AND TRI~1ING FOR ICE

The depth of water over the propeller tips should always be borne in mind when operating in ice, and the ship should be so ballasted and trimmed that the propeller is completely submerged and is as deep as possible. If this cannot be done and blades are exposed above the water or are just under the surface the risk of damage due to propeller striking ice is greatly increased. As a general rule, for operations in ice ships in ballast should have all ballast tanks full and be ballasted as deeply as possible, some ships being equipped to carry water ballast in a cargo hold or holds as part of normal procedure.

All ships have their own characteristics, and being trimmed by the stern may not always be best for operating in ice. Some ships handle in ice better when trimmed slightly by the head, but this can only be determined from practical experience. Trimming by the head means of course decreasing depth of water over the propeller, and this must be kept in mind.

The importance of ship's draft in ice is illustrated in Fig. 3 (a) a"nd (b) and in Fig 6\ 4. As can be readily seen, in light conditIon the ptopeller would be vulnerable to ice damage with the tips barely under the water surface. The extent of such vulnerability would depend on the thickness and type of ice.

Sometimes it is not possible to ballast a vessel to a suitable deep draft for ice, a condition which can easily develop in practice when there is ~o cargo on board. The least the navigator can do in such case is to avoid ice as much as possible and if forced to pass through ice, swing the stern away from the ice when turning in leads to avoid contact. If passage through heavy ice had to be made in this condition the risk of damage to propeller and rudder would be increased.

38

AVOIDING AND NEGOTIATING ICE

Figs. 1, 5-15 and others in the book illustrate methods used in avoiding or negotiating ice in order to accomplish speedy passages and at the same time reducing risks associated with ice.

As can be seen, large alterations of course and deviation from the intended routes are common and are in fact part of normal procedure, vessels occasionally steering almost opposite courses to avoid areas of heavy ice or ice under pressure. Experience has shown clearly that although by doing so distance is increased it takes less time to accomplish such passage with corresponding savings in fuel. On the other hand, passage through ice when ice has to be actually negotiated involves the following risks:

1. Risk of damage to hull, propeller and rudder;

2. Risk, in many cas(~s practically a certainty, of becoming BESET - this may mean long and costly delays waiting for an icebreaker, and there is also the additional risk of damage to propeller or rudder when efforts are being made to free the vessel, particularly when using stern power.

When passage through pack ice becomes unavoidable it should only be made in daylight and in good visibility. Sometimes it might become necessary to make such passages at night or in reduced visibility with the help of a searchlight if ice conditions and state of visibility allow (e.g. in an emergency or to enable a vessel to pass through a certain area in good time due to rapidly worsening ice conditions), but normally such tactics are not recommended and should certainly never be attempted by inexperienced navigators.

~~--.~-~-==-=--=======~==-----===========-======================~=~--

39

Speed on Passage through Ice

Once decision has been taken to enter and to proceed through pack ice, vessel's speed (always a most vital factor as ha.s already been demonstrated for good reasons) wilJ have to be carefully selected and then adjusted from time to time in accordance with ice conditions as passage progresses. The guiding factors will be: type, hardness and thickness of ice, concentration and the amount of open water or leads, visibility and the vessel's ice class and engine power. The decision at what speed to proceed is a difficult one: if too slow, vessel will be beset, and this could mean costly delays and increased risk of damage when trying to free her; if too fast, damage may result due to collisions with ice floes'# As a general rule, vessel must be kept moving or ice will stop her - although sometimes due to ice conditions it might be wiser to stop and wait till conditions improve. The normal recommended safe procedure is as follows:

a. avoid any hard ice in the pack and any larger floes. Go round the floes, not through them (inexp(~rienced navigators, particularly in~ Gulf of St Lawrence, have an inexpJicable suicidal tendency to persIstently try and slice through large floes ("t full speed - see Figs. 5 and 6).

b. when contact with any hard ice or with large floes becomes inevitable, use helm and engine so as to minimise impact and thus avoid damage.

- The use of radar in ice 1.S discussed briefly under RADAR, ICE AND SAFETY (ppe 72-73).

40

(a) Light

(b) Loaded

., , \

• I. ....• ··"v·'·",.(" .•••..•..

Depth of water propeller

I : ,'" ..Jt j . I

••• "to.,.........,"~ •••• ,~

over

FIG. 3 The importance of ship s draft and waterline in ice in relation to propell ~r and rudder.

41

Upper boundary

Ice Belt Zone

Lower boundary

Vessels operating in ice should be so ballasted and trimmed that any contact with ice would be made within the "ice belt" zone.

FIG. 4 Drawing showing the "ice belt" (shaded) in a vessel strengthened against ice

42

(> '. o

. O'.­~

.?f'

~ ---­ Actual track followed through pack ice utilising leads, patches of open water and lighter ice conditions generally, avoiding any hard ice or large floes. Note large course alterations and deviations from tne original track.

o 5 10

l- J

Miles

FIG. 5 When passage through ice becomes unavoidable.

'r, \., \ , \

(medium)

<6 ....

\, \

\, \

ice, damaged

"';)

!~3

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

" 71 " " '" . track--.. l~ e('omm('llded• / C,,' Ie

.- ";/l c?D / 0-,) "::l, ~c

d b ?/ > - / C2 LJ/ • C ~••0·

I ~c;c ~ 11 f D~ /)

LJ. I ~ / Floe (big)rhnb \. G

\ - '/- Beset

';::, \\ ~ t3ak (in hard

.::. \ ~ :'tj, ,as we 11)

Ci a••.~ ,,' I l\ .. 0 A : I\;J. "­\ , . /.'..-...... ----' ..--- \) 'b

·d... ".

It ... ","0 d1 ..., ....

I, I f

D~ /,O'l:" (f h

,. '...V' {1

o "

--- Intended tral.:k

FIG. 6 Avoiding large floes in the pack on passage through ice.

1

--

44

d d Safe Track Recommen e -- - :::- -" .-- -- "~

5025o

.........

\ \ \ \ \ \ \ \ \ ~

Miles

FIG. 7 Recommended safe track based on available ice charts.

45

D~~'O//'~~~/--'\: -(///1 C) :~~~O"l-J'bjt:/.!J0P"Ed···~··!/U(Dp,..'::::v·~·;,k-'~~O V ~ ~~ ~r\.ohf\.:V~ ~·:~G~U;- U . >:l t?c; LJ.?' ~<.r.d{(L .,.O' •••

'D" . t2 -- t1{~'\R~·(.\~ .~" ~.n.... a O~ub ~~'- ;'~~ : :5-,'L) ~ .. >~''0 ' ~ ~~U . )./ .{5/:70~j<l· .~ . c:::> .

<0 .., .•. ,.. • , .: 0 cO' .- ,

G ~ I'A ....:"", ."'.....

• • ...-•.l \ \

0·'· .. · I I

Open water

I

I

,.,7 - ,/ /'

I

(P '

::y- .... .--~

..... /

.//"

,.:>f... When approaching ice speed must be immediately reduced or engine stopped.

When entering ice vessel must be completely stopped or barely moving.

Entry must be made at right angle to the ice.

The point of entry should be carefully selected after scanning the ice before entering even if it means sailing for some distance so that entry is made where ice conditions are best for the vessel.

Once ice has been entered speed can be increased as required depending on ice conditions and the vessel's ice class.

FIG. 8 Approaching ice.

-..... .

I

f (

() I

/

. ~ . .(J" . / t . 't' . /

-1t /

/ /

/

FIG. 9 Danger fpatches of 0 damage t . pas nging inthrough open water or . 0 ship's sidpack ice. 1n leads d . e sageur1ng when owi

47

b

o I It> ,;

~t\"'Qp:~~~~p~\~r?7~9. i:lVt/:jVoO·r-----lJf\PQ.c--.. ~ ;;-7 l), VU/\'o

'j, " . '-----J'L> Q' ''0-.' . Dj /a CS c::::)' U ' .' 0" ~ • ~'q-1 0'( (~9J..~

. . ~"" .. V<,§ r, Contact , -- . \-:--:------<-----CEj ~~)V ~ '. \~C)--l/ 0 • 0, r.' ',I • ~ () rat) \' \ 1

\ 0 (\ [j-

A \' I.... \,)0

'j). U,Q)\ ~ \ .f0.. r1 0/'\

~Y:~?1 .. :~ D~A \ .....<\ VLJ J ,p J::"/\(I(lfl)\~ ~ (jOY--J . (J(J:~Do~<--J D<~~ ')/ U \\~Q~A d~~r1:fl o~\7:, I &S-/Il J\d V

r-.\J 1\ V 1\ t­/ ,'(s.u~j.) Q \j )'.

DV~rJo'-J~cJ~\'.GbnP:, ," /o' :'( ID"-J 0D o1)a.? J,. ~, ,

) A d .(1./) ~ '--.),. ~ () U··"V \~ 11 - b 6 "

' ~"~. l.>

~ a'C)({..' . . J, .cJ. . / ... " t>,

. D' '0' I ,/ h"D

, 0

~ I ••.••• :-'

000"",: • . - ...

With controllable pitch propeller it may become necessary in this case to "kill" the engine (i.e. to stop it as distinct from reducing pitch to zero) to avoid or minimise damage to the propeller when the stern is swinging and contact with hard ice becomes inevitable.

FIG. 10 Danger of the stern sevinging when passing through patches of open water or in leads with risk of damage to propeller or rudder.

48

Position 3

Close pack or hard ice

Position 2

Patch of open water or light ice

position 1

Close pack

When passing through this patch of light ice or open water speed may pick up rapidly if engine revs are maintained and must therefore be reduced in time so that on reaching Position 3 vessel is stopped or barely moving.

14 knot vessel, engine at "Full Speed", actual speed in ice: about 6 knots.

FIG. 11 Effect of ice conditions on speed when negotiating pack ice.

49

I j~--~: .. <.-'- . . .I -----ffl,,I.~._ ...~.· ',. •

'

~-~ .- ~ -" .. '., . '- """"......",,, .. ,, .. : -- /"-- . ". '''.~

Ram .. t.

'. , • . ~" .., Underwater part . '. ..

~1 '. :,~ .'

, . '°. 4

""'"

..~ " \ .. '" ..' -.,- -. -.-..-.-....•.. -. ,," ",

\.~

_-1", ? --. --! ;V-,~_.r. - '-..... - --..::. -- --::;:.''­," ,0'

....... •••• ,' .. '0 ... ' • " 0' ..........

:' '. 0' '0 .::.:::.~.,•

- ......:0' ..:

"

.'.

FIG. 12 Keep well <lear of icebergs.

I

-----

50

\ ' ... \

.... ".\

A \

\ \ \ \ \ \ \ \ \ I \ \ \

.' '1 "B"

. Ell In clear weather:

(1). Keep well clear of all icebergs. Do not pass icebergs less than t mile

... and preferably more.

": (2). Make a small course altera­tion of 2 or 3 degrees or so well in time rather.

Unnecessary, than a large alteration too large when the iceberg is very alteration close (see diagram).

: : :

•

.•

(3). In areas such as the Arctic the season can be very short. Frequent large un­necessary course alterations only prolong the voyage

•····,·•· and result in burning costly fuel for nothing,

,

···,,

,

·,·· At night or in poor visi ­bility (when it is still considered as safe to pro­"..' ceed at an appropriate speed):

Intended track from (4). Give all icebergs a WIDE

I"AU to BERTH. The reasons for this are illustrated in Fig. 14.

\ Good

II\

track (5). Sometimes a large and quick course alteration may be­come necessary; always bear in mind that any such alteration may result in

II~I

\ I

5o

~I

Icebergs Miles

contact with ice on EITHER SIDE OF THE VESSEL (see Fig. 35).

FIG. 13 Action to avoid icebergs and loose ice.

51

(a) WI~D

~. )0

~ ~~/\

\' : "'""'­ - '­ ~

'..

Debris from iceberg

_~.. ~ "­ /'-t A

1, ..../ t~.U" .::..j <.~./ 1.;J -;:;;;;r

.

",

\

" . \.

...._. ......

", ,0 ...... "

'~ :",...

• •••,.,lO

It must be remembered that wherever there are icebergs there may also be growlers or other ice debris which break away from icebergs and usually drift downwind, and which should be avoided (see diagrams above and below). Normally they should be passed to windward.

(b) '>~? WIND

Dt

\ .,. \

.-:;C~\ tmER~\ ~ ~O·::'

I \ I I \,,

Pass to windward if possible1 \

FIG. 14 Passing icebergs.

52

.'

SHORE

" .

.j,

A "shore lead" is a stretch of navigable water between pack ice and the shore. With an off-shore wind such leads can develop and are sometimes used by ships to avoid pack ice. When proceeding through shore leads the ice navigator must constantly watch for any changes in wind direction and in ice c onditions as with a change of wind his vessel may become trapped in ice with the risk of being driven ashore.

FIG. 15 Danger when proceeding through shore leads.

53

I_~-

ICE ICEI I

(1). Caution must be exercised when going astern in ice because of risk of damage to rudder and propeller.

(2). When going astern in ice make sure you are not backing directly into any hard ice with stern and propeller.

(3). If you have to go astern in ice make sure the rudder is DEAD AMIDSHIPS .

FIG. 16 Going astern in ice.

54

0. -""\ I ,,/ \

\/ >"I I \ \ ,/ / \

J\ / \ f \ / \ I\ / J\ / I ICEICE

/\ /\( \ / \ \ \ / I ---..~ I ~rJ

One way to free the vessel would be to go Full Ahead and Full Astern on the engine alternately throwing the helm hard-a-port and hard-a-starboard in order to swing her. This may loosen the ship a bit after a while when you can go Full Ahead and try to move through the ice if the ice is not too heavy.

IF THE SHIP STARTS MOVING ASTERN MAKE SURE TO PUT THE HELM DEAD AMIDSHIPS.

FIG. 17 When beset (1).

55

-----. i,--­

\ . I \I , ; \

! ~..r-~

I, ~~ .r:-::..-..+-+--+--J.:.:""'t I

I t . ". "h.

!--.:=-:--:-----;('----->----.,--:::--'\...--'~\ 7~--:--=... -~I ,'-------. ,. \ Ii . \. /"

-" --........ • p " ..... ;0 ... \ '-- -­ , .. '--..... ' •• ' '.' "0' _,"". '. ' ••••••.• - '-, _ ,-' __/1 .,'

, _. I

I

, II 1-'(~-J.

j _/

,/-- --I,....i .1...__... _. -_._---~~,..---.

':7~ -_. _#"._- _.. ~."""--._. - -" -.-.

,-"","", ~. - . .. .. . '---.­

' ....­-- ,.' ....-~ --"'" -­

Another way to free the vessel would be to pump and transfer ballast (or, in a smaller vessel, to move deck loads if this was possible) from side to side alter­nately so as to produce list and loosen the ice, or even pump ballast to change the trim. This, however, is a somewhat lengthy and time-consuming procedure not normally used in larger vessels although it could be employed if there was no other way to free the vessel and ensure passage through ice if an icebreaker was not available.

FIG. 18 When beset (2).

56

RAMMING AND BACKING IN ICE

In the course of this procedure ice is rammed with the bow while moving ahead in order to break it by sheer impact and weight as illustrated in the drawing, and then the vessel is backed out of the ice and into the broken ice astern. The procedure is then repeated, and in this manner slow progress can be made ahead through a patch of heavier ice so as to reach open water or an area where ice is less heavy.

':. ~ .. " T \ ...... ~ '"

".. _ .... " <T ~ ., .... , . - .. ........ , ,. v· .

,' .... ~

BROKEN ICE UNBROKEN ICE

IMPORTANT NOTE :

This is a dangerous procedure which should be used with utmost discretion as heavy damage to the vessel could easily result. Particularly in heavy or in hard ice it should never be attempted by vessels with low or no ice class and with a bulbous bow, except possibly in some extreme emergency.

FIG. 19 Ramming and backing in ice.

57

Escorted vessel

FIG. 20

2J The bow of the escorted vessel't '. (point "A") must follow the track .~ •.~ of the icebreaker's stern t\} Q::~ (point "B").\Y 'D ~. .

V..·• ~ A J C)to \\ c=;:J, ""5;..:[" L) "'M· A' . ';,~~ , .. , ,. .~

'. -,...,0···· '-b -.!.'(~', ~c~.,.~. n (l' ,Cl,o,Cj \U u,~,.Up ....:..., '.:, ,

1

." 0. ~~CS' .b p"~., Do

\ ..,~. .t '" ... : . ~', . ., " '. ' \ . ~ 0 C"'""'- • ~ • ' "" ~ '. I" 'i JI /f.. ., . \ ./ ". J

Following an icebreaker in ice - correct procedure in curves (1).

58

: Escorted vessel

- NOT LIKE THIS ...

k 'n ice - correctFIG. 21 Following an icebrea(~r).~ procedu~e in curves

59

FIG. 22 Following an icebreaker in ice - correct procedure in curves (3).

60

' NO PRESSURE IN ICE

T en goodrack stays op 'icebreakerd between bistance sel can eI d escor t ed ves'an d '' maintaine . i

I i

I i ----- distance~--- ~ icebreaker ­

FIG. 23 astern Ol.Following k r (1).from icebrea e

61

ICE UNDER PRESSURE

Track closing rapidly, escorted vessel must keep as close as possible to the icebreaker if progress is to be made.

FIG. 24 Following astern of icebreaker - distance from icebreaker (2).

62

Unsafe positions 1 and 2; risk of damage to hull or propeller due to contact with ice near the edges of channel made by icebreaker.

FIG. 25 Following an icebreaker in ice - no pressure in ice.

63

'e/.'-t..

,01s••••

[6.

"

. .

" :' ~~

0

r> _= r----.~ c=::> Cj~v~. 1:::5.;-<?,~,~~~, pbQ:~\ --;!):: IC~breaker 0 I tS.' '~i~~~6

\\) ..,,~~~"-. ,. ~':~ r(~ '" '\~~\ , " {J~::j H''Y [J

':'~" "'\, '" .~. ',"':0" ~: r-... . "', ,/1 )\ "I } ,,~ ••

, " I· :/ (., D."'\>' , ..,()~" ,~Oi. " ~;,;,~,.W·V':;,'. ~. '.... ." .. :. • \J~ , , ,. .

~ <""--.., , ~ B-" , , , \) . ,00 ~ :,'," ... ,. ~'"'. ..... .. .:., . "'. ,- ,~ .. , ...... :... ,,' ~' .. '

Ice sometimes dis- .:. ~I\J' , \ ~'::" \.' p" 'n lodge~ by, icebreaker, t·· ••" ~ , " :",' " VI

float1ng 1nto and '., ",'.' .

"0 '~, \ ';'~'D cJ ': ~ \)\ \ . '::. :,:,>. '06 '()vI

\ ,"..t. <U;.

v ----.J / '"'--' u~ \\ . 1/(I:/J ~' 0 ')

- I'

:D.,:·· \

\.~ ~ .. :A'::.

..... C--J ~ DQ~\. ~ O~ a,·::;~~ \'

..' UlJJ) \\ \\ ' , ': Escorted ~.

l\ \'" r-----.. 0 , i: 'l to- ,,' ' ~ ,'\ 1 \

~',,' ":' , ';,\~ I "

.. /\ VCj L) 6 '. .- L,.J,' ,:.' t:>" . 6.c311, .. t8~

FIG. 26 Following an icebreaker in ice - danger of running into ice dislodged by icebreaker.

64

Go hard-a-port or hard-a-star­board and bury the bow in the ice. Stop the engine and go Full As tern.

Heavy Ice

In hard or heavy ice this manoeuvre WILL NOT WORK as the bow will be deflected by the ice, therefore go Full Astern in time to avoid collision.

FIG. 27 Operating astern of icebreaker in ice ­emergency procedure when icebreaker unexpectedly slows down or stops.

65

.'. 'J

'p'r

Shel ter Area

Shore

Ii

r-'11ft; J) Dock(:):;0 j

O:,Q (1/ J

o····~~········ I~ "/':' ~ Shelter

C-J Area

r; .~

.. 0:O·~

J6 ..:: I I ~

(a). In harbour: alongside (b). In the lee of the or at anchor. land.

Note: when sheltering for only short periods or in emergencies in either of these situations vessel could1Movement of drift ice be merely stopped using helm and engine to maintain posi­tion until the danger was past.

r'-----·

FIG. 28 Sheltering from drift ice when there is current or tide.

L

66

D

o

c

K '<6 4' '.",

(~

Recommended procedure:

(1). When drift ice is present (as in a river berth in winter) do not allow mooring lines to be slack. Once ice begins to accumulate between the dock and the ship's side it may be very difficult to bring her back alongside, and mooring lines may carry away under pressure as has often happened in the past. If ice begins to form under the stern it may become necessary to turn the propeller from time to time.

Experience has demonstrated clearlyl (2). that if ice is heavy nothing will hold the vessel, not even anchor cables secured ashore.

(3) . When lying alongside an exposed dock which lies in the path of moving heavy drift ice or icebergs careful watch must be maintained on ice conditions and engine kept on stand-by or at short notice so that vessel can cast off quickly and move temporarily to a safer area nearby to seek shelter and re-moor when the ice is gone. In Canadian Arctic ports and anchorages where there are no pilots this is standard procedure.

WHEN MOVEMENT OF HEAVY ICE IS IMMINENT, IN THE ABSENCE OF ANY WORD FROM SHORE THE MASTER WOULD BE WELL ADVISED TO TAKE INITIATIVE HIM­SELF, ORDER A PILOT IF THERE IS STILL TIME AND THE AREA IS A PILOTAGE AREA, AND MOVE TO A SAFER BERTH. IF THERE IS NO TIME, CAST OFF AND LOOK FOR AN AREA SHELTERED FROM ICE. DO NOT STEM LARGE FLOES IN A CURRENT - IT IS USE­LESS AND DANGEROUS. IF IN DOUBT BEFORE CASTING OFF CONSULT LOCAL PILOTS BY RADIO, BUT IF THIS IS NOT POSSIBLE PLAY IT SAFE, CAST OFF, LOOK FOR SHELTER AND DO NOT GET CAUGHT IN HEAVY ICE.

Unsafe berths in icebound ports.FIG. 29

67

.<f If) e;;:.---7

o

"\,, " "

Recommended procedure:

(1). Put a good spring out on the dock from forward, preferably a double spring or better;

(2). Use helm (starboard in this case) and engine (ahead) to swing the stern in and out and away from the dock. Keep engine going ahead until the wash from the propeller sweeps away all the loose ice, then dock her.

Sometimes it may take several hours to dock the vessel in this manner in ice, but there is no other way unless vessel has tug or shore assistance.

'- .... ~

j)

v .,

(J ~

D

o

c

K

FIG. 30 Docking alongside when ice is present.

68

111 /11.

" ,I

, \ \

+' I

I ('

~, 103 '-.

'" ~..,q "-

"All

"

+ .

B

+' , UNSAfE

TRACK\

I ..

"'\11

0~l? /12..

1/6"'. ", 6 q

J

J 77

I l' J /oj,

0

/" 87

;"

I 95'

,-f.11~ I

18

" COMZECT

TI\A C1<'

FIG. 31 The correct use of Canadian Arctic charts.

(1). Ships must navigate wi th caution when in Arctic waters as much of the information on charts is of a reconnaissance nature, and many of the charts are marked to this effect.

(2) . As an example, when proceeding from point "A" to point "B" as shown in Fig. 31 above, the track must follow the line of soundings even if this means an increase in distance. Blank areas with no soundings indicate that these areas have not been surveyed, that depths are not known, that there could be rocks, shallows or foul ground, and SUCH BLANK AREAS MUST THEREFORE BE AVOIDED.

69

Normally a good target

,,' , '

,/r '

j. "II" ','-

Iceberg1 ./

~ / i\

~ _ ............ _' .._,./'I /' ~ --? .,

i \

r" ,

II '

I \

f \ I \

'\

Not so good

Bergy bit .~/;~

,, .... , I .. ,I

( .... ....

'\

Very poor target

(GROWLER with seas breaking over it)

----'----"'---~----.~ j ., ............ .....---... ~-------~---... ~.

.' ,\ .

......... '

IN DARKNESS OR IN POOR VISIBILITY SLOW DOWN OR STOP

THIS IS STANDARD PROCEDURE

FIG. 32 Glacier ice as radar target.

I

70

Iceberg -----...,~D

Open water

Floe

Brash ice

"

./ ., .'\11

I.J Pack ice

Floe

Iceberg

Growler

Sea surface: moderate or slight sea. Growlers do not show up or are lost in the clutter. Smooth floes may appear as open water. Open water with brash ice may appear as ice of undetermined type.

FIG. 33 Ice as it may appear on the radar screen.

71

Iceberg

Iceberg

I ()

[)

,. ~

(/

4 q

Shi-p

Floes

, (@

.:' ;::'~:~~)&::' "' , ....-.J.,... ' · f:'f,~:·:·:,;· '" ~ .." ,.... .J (

, ~

~\ , @',

Sea surface: smooth sea. In this case echo from another ship may appear the same or very similar to echoes from icebergs. In poor visibility this could result in a potentially dangerous situation.

FIG. 34 Ice and ship targets as they may appear on the radar screen.

72

RADAR, ICE and SAFETY

Notes and Recommended Procedures.

(1). Ice is an inferior radar target and may not return echoes.

(2). Due to ducting effect, temperature inversion, weather conditions and other factors, EVEN ICEBERGS may sometimes not show on the radar screen.

(3). In rough seas radar is practically useless for detection of small bergs, bergy bits or growlers. The ice navigator can rest assured that under rough sea conditions a growler will be lost in the clutter or, being awash with the seas breaking over it, the echo may never be returned, particularly in rain or in snow.

(4). Pack ice may be detected by radar at a distance of several miles, but once in the pack radar is normally of not much use. Smooth ice may look like open water, and open water with brash ice in it may look like ice. Furthermore, radar will only return echoes from the ice but will not tell the navigator what type of ice it is and how hard or how thick the ice is. Icebergs usually return strong, almost unmistakable echoes, but this must never be taken for granted. Under certain conditions radar has been of help as it may show leads and patches of open water, but generally conning on passage through pack ice is done by eye alone. The author has found radar very useful for detection of batture floes in the estuary of the St. Lawrence River when these floes were surrounded by open water.

73

(5). If the visibility and ice conditions are still such that you can alter course for the ice in time or bring the vessel to a complete stop in time to avoid ice, proceed with utmost caution at a safe speed with sharp radar AND visual watch maintained, ready to stop or to manoeuvre at any time.

(6). In reduced visibility when ice is present or can normally be expected it is dangerous to proceed. If the visibility is such that course cannot be altered or ship manoeuvred in time to avoid ice, STOP AND WAIT TILL VISIBILITY IMPROVES SUFFICIENTLY before resuming passage. If this takes place at night, STOP AND WAIT TILL DAYLIGHT. In some cases radar can be used to assist when passing through very open pack of low concentration or through an area where loose ice is present at night or in reduced visibility (when the navigator can still see sufficiently ahead) provided the sea is SMOOTH, radar reception GOOD and SMALL ICE CAN BE DETECTED, but this type of passage requires experience and even then should always be attempted with caution.

(7). In Arctic waters or elsewhere when a multitude of icebergs can be seen on the radar screen at night or in reduced visibility as is often the case, it would be wise to remember for safety's sake that any of the echoes could be another SHIP on collision course or nearly so. This is known to have happened in practice in the past.

- Figures 32, 33 and 34 illustrate some of the problems associated with radar reception in ice at night or in reduced visibility.

(Note: the above remarks apply to conventional types of radar such as are normally carried in commercial vessels. New advanced radar systems for use in ice are presently being developed and tested, and if successful may well change the whole concept of ice detection and ice avoidance).

74

GENERAL SAFETY RULES ON PASSAGE THROUGH WATERS WHERE ICE IS PRESENT OR CAN ' NORMALLY BE EXPECTED

Ice

o p:J .-,-­

Range of

visibility

0 c1-... _--G1-t::.f

(1). The entire sector ahead of the vessel's beam must be contin­ually watched by the lookouts with the aid of binoculars for any signs of ice, particularly the vital sector directly ahead of the vessel which must never be left unattended. Vessel must be ready to alter course at any time to avoid ice AND to reduced speed if necessary.

(2). When visibility is reduced or when ice concentration increases, or both, it may no longer be safe to merely alter course to avoid ice ahead as by doing so vessel may run into other ice on either side, as shown by the dotted line in the diagram. In this situation SPEED must be such that on sighting ice vessel can be brought to a complete stop in time or manoeuvred in time to avoid it, always bearing in mind the degree of ice concentration and type of ice.

(3). IF DUE TO VISIBILITY CONDITIONS OR OTHER CAUSES SUCH YtANOEUVRING BECOMES TOO DIFFICULT OR TOO RISKY, OR IF IN DOUBT AT ANY TIME, STOP AND WAIT TILL VISIBILITY IMPROVES,

FIG. 35 General safety rules on passage through waters where ice is present or can normally be expected.

7S

USEFUL HINTS and OBSERVATIONS

1. Anchoring in ice.

Not recommended because of risk of damage or losing the anchor cable. Cargo ships working cargo off a "beach" using barges occasionally anchor, but are always ready to pick up the anchor and move to a safer area when ice starts moving in. Use helm and engine to maintain position instead of anchoring. If anchoring, only very short length of cable should be used so that the anchor can be picked up quickly if necessary. Windlass should be kept ready for instant use, and of course strict watch maintained for any drift ice.

2. Towing in ice.

Towing in ice has been successfully accomplished by icebreakers and other vessels on some occasions in the past, but normally towing is not recommended except in emergencies. In heavy ice it would certainly be very difficQlt if not impossible. Special towing (or pushing) techniques are sometimes used by icebreakers and other specialised vessels in the Baltic and elsewhere, but these are outside the scope of this discussion.

3. Braking effect of the rudder.

It is very useful and important to remember that during passage through ice frequent use of the helm especially in the hard-over position has the effect of slowing down the vessel, and this can be used to ,advantage so that reducing speed using the engine with the consequent loss of steerage can be avoided. It will also assist to bring the vessel to a crash stop in an emergency. On the other hand, when pushing through ice or proceeding astern of an icebreaker giving too much rudder may bring the vessel to a complete stop, and this should be borne in mind to avoid unnecessary delays.

76

4. Light and signals for vessels beset.

When beset in ice or when stopped in ice with the engines shut down it is customary to display the "Not Under command" (NUC) lights and shapes in daytime or at night when there are other ships in the vicinity.

5. Abandoning ship in ice.

Experience of ships being abandoned while in ice indicates that both lifeboats and liferafts can sometimes be placed on the ice. While still on the ice floes inflatable liferafts would provide a most useful and needed temporary shelter.

6. Freezing of ballast and fresh water tanks.

To avoid risk of damage to tanks due to freezing the usual practice is to keep the tanks not more than 90% full to allow for expansion. Exposed side or top side tanks would be particularly vulnerable during windy weather with the chill factor in effect. Double bottom tanks might also freeze, particularly in the case of a vessel lying alongside the same dock for extended periods. Fresh water freezes at 0° C. and sea water at about _2° C. depending on salinity, therefore tanks filled with salt water might freeze a little later or might not freeze if temperature did not fall sufficiently low. In the case of vessels actually in pack ice (which has a damping effect on swell) the free surface effect would probably be practically eliminated or reduced, hut would of course be felt once the ship reached open water. With a vessel under way and ballast tanks only partly full the risk of freezing would be reduced due to the movement of water inside the tanks.

77

7. Freezing of fresh water tanks in lifeboats.

Fresh water tanks and water containers or cannisters in lifeboats would also be subject to damage from freezing, and should be kept no more than 75% full. In sub-zero weather they would freeze anyway, and in the event of abandoning ship the crew would be faced with the prospect of having no fresh water, only frozen water tanks. It would be very useful for vessels operating in such cold regions to carry small fuel-burning stoves for melting ice or snow as part of normal life-saving equipment. In some Canadian ships operating in ice regions water containers for lifeboats are sometimes kept inside the heated accommodation near the boat deck ready to be put into lifeboats in case of an emergency.

8. Additional fuel and stores.

Additional fuel, fresh water and stores should be carried in ships operating in ice regions to allow for delays and stoppages in ice due to ice conditions or while waiting for an icebreaker. Also in the case of ships uaing lighter grade fuel for manoeuvring, consumption may increase rapidly as manoeuvring in ice over extended periods may be involved.

9. Searchlight

For ships operating in ice a good searchlight is a MUST as it will enable the vessel to proceed at night under certain conditions, rather than be stopped and lose valuable time waiting for daylight. It should be carried preferably forward in the bow so as to throw a beam of light directly ahead of the vessel. Sometimes in smaller ships small searchlights mounted on the upper bridge or in the bridge wings have been used with some success, but in a larger vessel with the bridge and machinery aft such searchlight would be quite useless and would probably blind the navigator as well.

78

10. Recommended miscellaneous useful items and equipment:

- Salt and sand in bags for melting ice on decks, gangways etc.

- De-icing liquid in containers or spray cans for de-icing and cleaning of wheelhouse windows in sub-zero weather. Vinegar is as good a substitute as any for cleaning windows when there is nothing else, using soft cleaning paper or old newspapers instead of rags.

- Anti-freeze for lifeboat engines cooling systems.

- Plentiful shovels, scrapers, crowbars and hardwood mallets for removal of ice from hatches, decks etc.

- Warm clothing for the crew.

- Safety harness for going over the side to take drafts from ladders etc. Falling into the water in cold regions where ice is present or when temperature is close to zero would mean a certain and quick death from hypothermia (loss of body heat) unless some form of rescue was immediately available which is usually not the case.

- Vessels operating in cold regions with open bridge wings and bare steel decks should have wood gratings in the wings.

- Some ships in which view from the wheelhouse is badly obstructed by deck cranes, masts etc. have to be conned while in ice from the upper bridge, usually an open bridge. It would be extremely useful in such cases for the sake of comfort (and safety) to have at least a suitable shelter erected on the upper bridge for the conning officer or the ice pilot. If such shelter has windows, experience has shown that these should be made of glass (not plastic) for easy cleaning and de-icing without damaging the surface when they become useless.

- THE END ­

79

RECOMMENDED READING

Armstrong, Terence Brian Roberts Charles Swithinbank

McDonald, E.A., Capt

Armstrong, Malcolm C.

ILLUSTRATED GLOSSARY OF SNOW AND ICE, Second Edition Scott Polar Resear'ch Institute Cambridge 1973

POLAR SHIPHANDLING Arctic Institute of North American, Washington D.C. 1965

PRACTICAL SHIP-HANDLING Brown, Son & Ferguson, Ltd. Glasgow 1980

ICE NAVIGATION IN CANADIAN WATERS

Government of Canada Ottawa 1972

Sailing Directions ARCTIC CANADA, Vol. 1

Government of Canada Ot tawa

Sailing Directions GULF AND RIVER ST. LAWRENCE

Government of Canada Ottawa

80

THE MARINER'S HANDBOOK

Ministry of Defence Taunton 1973

MANUAL OF ICE SEAMANSHIP H~O. Pub. No. 551

u.s. Navy Hydrographic Office Washington D.C. 1951.

81

Abandoning ship in ice,

Additional fuel and stores,

Anchoring in ice,

Anti-freeze,

Approaching ice,

Arctic whalers,

Astern, going in ice,

Avoid ing ice,

Ballast tanks, freezing of,

Ballasting and trimming for ice,

Bergy bit,

Beset in ice,

Braking effect of the rudder,

Brash ice,

Bummocks,

Canadian Arctic charts, correct use of,

Charts, ice, recommended safe track,

Close pack,

Concentration, ice,

Conning ship in ice,

Compact pack,

Consolidated pack,

INDEX

76

77

75

78

45

I

53-54

31, 34, 38, 42-44, 49-51, 57-60, 62-63, 65, 73, 74

76

31, 37

2, 6, 69

54-55, 76

75

5, 20

24

68

68

18

9, 26

I

18

18

82

Damage to ship's side,

Danger of stern swinging,

De-icing liquid,

Docking alongside in ice,

Draft, of ice,

Draft, ship's and waterline,

Drift ice,

Fast ice,

First year ice,

Floebergs,

Force of impact,

Free surface effect in ice,

Freezing of ballast and fresh water tanks,

Freezing point of water,

Fresh water ice,

Glacier (glacial) ice, as radar target,

Gratings for bridge decks,

Grease ice,

Grey ice,

Grey-white ice,

Growlers,

Hummocked ice,

Hypothermia,

46

47

78

67

1, 9

40

65-66

21

3, 12

25

30, 35

76

76-77

1

2, 10

2, 6-8, 14 32, 72

78

3, 10

3) 11

3, 11

2, 6, 14, 70, 71

24

78

83

Ice, after snowfall, 15

brash, 5, 20

cake, 20

colour of, 10-15

concentration, 18

disintegration of, 5

drift, 65-66

fast, 21

first year, 3, 12

floating, 1, 2

floeberg, 25

floes, 19-20

frazil, 3, 10

fusing of, 27

general definitions, 1-28

glacier (glacial), 2, 6-8, 14

grease, 3, 10

grey, 3, 11

grey-whi te, 3, 11

hardness of, 4, 9-15

honeycombed, 5

hummocked, 24

84

Ice, i~e~tification of,

:'slands,

keel,

lake,

new,

melting point of,

multi-year,

old,

pack,

pancake,

patch,

pressure,

puddles,

rafted,

ridge,

rind,

river,

rotten,

sea,

seamanship,

shelf,

specific gravity of,

speed in,

strips,

thickness of,

9-25

22

24

2

3,10

1

3, 13

3, 13

18

3, 11, 20

25

26

5

24

24

3, 10

2

5

2, 3-5

30-78

21

1

30-31, 35-36, 39, 48, 64, 73-74

25

3, 9, 10-14

85

Ice, types of,

uniform,

unscheduled contact with,

"white",

young,

Ice belt, in a ship,

Icebergs, general,

detection of,

keeping clear of,

Icebound ports,

Icebreaker, working with,

Ice class, of a ship,

Ice keel,

Ice sense,

Lake ice,

Leads, in ice,

Leads, shore,

Nilas, 3, 10

Old ice,

Open pack,

Open water,

2-3, 6-8

28

32

3, 12

3, 11

31,37,41

2, 6-8, 14, 17, 23, 36, 49-51, 69-73

17, 69-73

49-51

66

57-64

II, 32, 39, 41, 45, 56

24

I, 33

2

34, 43

52

3, 13

18

18

86

Pancake ice,

Patch, of ice,

Power, indiscriminate use of in ice,

Pressure in ice,

Propeller, depth of tips under water,

Puddle, 5

Radar, ice and safety,

Rafted ice,

Ramming and backing in ice,

Recommended miscellaneous useful items and equipment,

Recommended safe track based on available ice charts,

Ridge, 24

River ice,

Rotten ice,

Rudder, braking effect of,

Rudder and draft in ice,

Safety harness,

Safety in ice,

Salinity of water,

Salt, in bags,

Sea ice,

Searchlight,

Sheltering from ice,

Shuga, 3, 10

3, 11, 20

25

I

26

31, 37-38, 40

70-74

24

56

78

44

2

5

75

37-38, 40

78

30, 72

1

78

2-5, 10-13

77

65-66

87

Slush ice,

Snow cover on ice,

Specific gravity, fresh water

icebergs,

ice generally,

Speed, effect of ice on,

Speed in ice, excessive,

Speed in ice,

Stability of icebergs,

Stopping in ice,

Strips, of ice,

ice,

3, 10

9

1

1

1

48

30-31, 35-36

30, 35, 39, 48,

8

30, 33

25

64, 73-74

Tabular bergs,

TITANIC, R.M.S.,

Towing in ice,

23

31, 32, 36

74

Unscheduled contact with ice,

Unsafe berths in icebound ports,

32

66

Very open pack,

Very close pack,

18

18

Warm. clothing,

"White" ice,

78

3, 12

Young ice, 3, 12