GOALDS MHuss Presentation 2010-09

8/8/2019 GOALDS MHuss Presentation 2010-09

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GOALDS WS 2010-09-08, M Huss

RULES AND STANDARDS

should define what is to be

achieved (safety of lives,property, functionality ...)

should express publicexpectations on performance

Rules Standards

provide a broad spectrum of requirements on design and

operation of ships that together will lead to an acceptable

level of safety

compliance with standards = fulfillment of expectations

Traditional IMO regulations are a combination

should provide a common

understanding of how thingsare to be done

should facilitateimplementation and

communication

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GOAL-BASED STANDARDS

Explicitly formulated objectives, functions andstandards distinguished from each other

Objectives are achieved by fulfilling functionalrequirements; standards are provided as solutions

May provide a generic scheme for the formulation ofrequirements and regulations for the future, that willfacilitate:

Safety monitoring and analysis

Alternative solutions

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MAJOR IMPACT OF SOLAS 2009

Harmonized assessment methodology for dry cargo

and passenger ships survivability after a collision

Ended a long era of prescriptive requirements ontransverse bulkheads and subdivision of passenger

ships based on floodable length and margin linecriteria

Reduced variation in actual survivability performanceand at the same time increased flexibility in designsolutions for passenger ships

Increased survivability of new ro-ro cargo ships andlarge passenger ships

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A PERFORMANCE STANDARD

The standard does not stipulate how the ship should

be subdivided, instead the performance of aproposed arrangement is evaluated for typicaldamage scenarios

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The probabilistic methodology introduces a varietyof test scenarios that will cover real contactsituations better than a few representative test cases

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! ! !

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

p2

p3+4

p5+ p

6+ p

7+ p

5+6+ p

6+7+ p

5+6+7


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The probabilistic methodology introduces a varietyof test scenarios that will cover real contactsituations better than a few representative test cases

The performance is on the other hand evaluated byrather generic criteria that may not fully cover everypossible chain of events after a flooding

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CORE COMPONENTS

1. Required overall level of survivability accountingfor any foreseeable situation where the ship haslost some of its watertight integrity (index R).

2. Distributions describing the degree of survivabilityunder a specific damage (s).

3. Distributions describing damage position andextent (p, r, v).

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DAMAGE POSITION AND EXTENT

Based on scattered collision statistics from a variety

of ship types and situations

Generic distributions coupled to length and breadthnormalized with respect to the stroked ship size;

Vertical extent described by a constant distribution(increased compared to previous for cargo ships)

Improvements: to include grounding (and other largescale flooding below the WL) in the genericdistributions

Recommendations: to maintain a simple and robustformulation of damage distributions

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SURVIVABILITY

The basis is a common format based on three

characteristics of the GZ-curve at equilibrium afterflooding (range, max, heel). Only heel differsbetween cargo ships and passenger ships

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SURVIVABILITY



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0 5 10 15 20

Range

0

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0.9

1

s

new GZ!0.12

new GZ=0.10new GZ=0.08

new GZ=0.06

new GZ=0.04

new GZ=0.02

existing GZ!0.10

existing GZ=0.08

existing GZ=0.06

existing GZ=0.04

existing GZ=0.02


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SURVIVABILITY



Additional requirements for passenger ships forintermediate stages of flooding and heeling moments

Evacuation routes are to be effective after flooding

Improvements: could well be differentiated fordifferent arrangements and ship types as needed inorder to better describe capability; as long as thesurvivability measure is kept on a comparable level!

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REQUIRED OVERALL SURVIVABILITY

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In the case of passenger ships:

R =15,2252.5

5,0001s ++

!

NL

In the case of cargo ships greater than 100 m in length (Ls):

R =152

1281

s +

!

L

Previous SOLAS Ch.II-1 B-1:

R = (0.002 + 0.0009Ls)

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3

Res. A.265(VIII):

R = 1!

10004Ls + N+1500

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No of passengers (Ls=100,200,300,400)

Requiredinde

xR

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Requiredinde

xR

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Requiredinde

xR

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Requiredinde

xR


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REQUIRED OVERALL SURVIVABILITY

Is based on the weighted sum of survivability atthree different loading conditions (ds, dp, dl) that doesnot necessary follow the actual operational profile

Improvements: If we believe to have representative

models for damage distributions and consequenceswe should aim at harmonized also the safety levelrequirements

Future development: R could be expanded/dividedinto separate components (terms) to includedifferent safety targets (lives, property,environment ...)

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SOLAS 2009 AS DESIGN STANDARD

Increases dramatically the extent of analysiscompared to deterministic standards, but enablesmore flexible design solutions

Not ideal for easy design optimization but supportsidentification of safety critical design spots

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SOLAS 2009 AS DESIGN STANDARD

Increases dramatically the extent of analysiscompared to deterministic standards, but enablesmore flexible design solutions

Not ideal for easy design optimization but supportsidentification of safety critical design spots

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Consideration to meet higher damagestability standards

Additional watertight deck 8 abovefreeboard deck

Raise position of air vents from abovedeck 8 to above deck 10

Result (GM=1.4/1.0/0.85)

R = 0.663 A = 0.513 (vents above deck 8)

A = 0.739 (vents above deck 10)


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SAFETY LEVEL IN SOLAS 2009

A more consistent level of safety than in theprevious deterministic rules

The probabilistic standard has obtained an equalgeneral level of safety, and taking SOLAS 2009 as a

whole the level has been raised for most ship typesconcerned

Water-on-deck for ropax ships is still under dispute

since it is not explicitly targeted within the presentsurvivability criteria

Is the safety level sufficient?

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SUMMING UP THE STATUS

SOLAS 2009 has achieved:

harmonization of the methodology to assesscollision damage stability for dry cargo and

passenger ships

a more consistent level of safety and at the sametime increased design flexibility for passengerships

the basis for a clear structure that could beincorporated into a goal-based standard system

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SUMMING UP THE STATUS

SOLAS 2009 has not yet achieved (but could befurther improved and developed to achieve):

harmonization of damage stability assessment for

all types of flooding causes and all types of ships

fully comparable survivability criteria (s)

harmonization of safety level requirements (R)

the optimum regulation text

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GOALDS MHuss Presentation 2010-09

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