Rogue Waves 2004Rogue Waves 2004

Ship design rules and regulations – an

overview of major themes

Gil-Yong Han

Int’l Association of Classification Societies

An overview of major themesAn overview of major themes

IMO Goal-Based

Standards

IACS Common Structural Rules

* Freak Waves

Risk-Based Approach

Role of IACSRole of IACS

•SETTINGSETTING

•IMPLEMENTINGIMPLEMENTING

•MONITORINGMONITORING

RULES’RULES’Hull structure + machinery engineering

What are the class rulesWhat are the class rules

Complying with Class Rules:- Provision of adequate global strength;(ships capable of withstanding still water and wave induced loads

with the specified stress criteria)

- Provision of adequate local strength of individual components

(steel material requirements and scantling formulations are to ensure that ships resist modes of buckling, fatigue, yielding, brittle fracture)

- Rules provide direct calculations procedures for determination of scantlings.

Relation with IMO and flag States

IMO Conventions – Statutory RequirementsSOLAS Convention states that in addition to the Conventions requirements, ships shall be designed, constructed and maintained in compliance with class rule requirements of a classification society which is recognized by the Administrations;

Many of the flag States authorize class societies to apply the IMO Conventions (statutory req.) on their behalf by design appraisals and surveys.

What IACS can not doWhat IACS can not do

A strength of “classification” concept is that the Societies act as independent bodies, giving an independent and unbiased assessment of the status of ship’s hull and machinery;

However, they are not guarantors of the safety as they have no control over how a ship is operated and maintained.

The current regulatory framework – The current regulatory framework – shipping safetyshipping safety

Coastal StateRegulations

Flag StateRegulations

UnderwritingClauses

OperationalProcedures

IndustryStandards

ClassificationRules

InternationalConventions &

Regulations

Safety & QualityManagement

Systems

Port StateControls

Chartering &VettingCriteria

Risk-Based Approach in shippingRisk-Based Approach in shipping

In many cases, enhancing the safety rules (structure incl.)

were driven by accidents;

Following high profile accidents (Herald of Free Enterprise,

Exxon Valdez, Piper Alpha), a risk-based approach in ship

design and operation was introduced;

IMO, supported by IACS, recommends FSA to be applied, to

examine potential areas and introduce risk reduction

measures before a tragedy happens.

Bulk Carriers – top priority.

Example: BC Accidents Trend Example: BC Accidents Trend

LOSS OF LIVES

0

20

40

60

80

100

120

140

160

180

200

Years

No

. li

ves l

ost

BULK CARRIER LOSSES

0

5

10

15

20

25

1990

1991

1992

1993

1994

1995

1996

1997

1998

1999

2000

2001

2002

Years

No

. vessels

lo

st

0 10 20 30

Collision

Grounding

Structural

Flooding

Machineryfire/explosion

Machinery failure

Cargoloading/unloading

Cargofire/explosion

Cargoshift/capsize

Contact object

Unknown

1993-2001

2002

Source: INTERCARGO Annual Report 2002

ChangesChanges

• A systematic method is put in place to establish the ship safety

rules of the basis of assessment of risks, costs and benefits –

final decisions are now robust and defensible.

• However, this risk-based approach “supplements” the traditional

prescriptive rule-making, allowing variation from prescriptive

rules, provided that the ship (system) risks are maintained at

acceptable levels.

Widespread consensus -

Make ships durable and fit-for purpose

ExpectationsExpectations

Regulatory Regulatory ExpectationExpectation

SafeSafe

Environmentally Environmentally friendly friendly

Easy for inspection Easy for inspection and maintenance and maintenance

Industry Industry ExpectationExpectation

Robust and ReliableRobust and Reliable

Fit for purpose Fit for purpose

User friendlyUser friendly

Goal-Based StandardsGoal-Based Standards

Common RulesCommon Rules

New regulatory frameworkNew regulatory framework   

2

3

REGULATION

SELF-REGULATION

Safety objectives

Risk acceptance

criteria

Prescriptive rules

Policies, management systems and best practices

Operational requirements

Objectives Objectives –– Common Structural Common Structural RulesRules

• To eliminate competition between class societies on standards

• To embrace the intentions of the anticipated IMO requirements for Goal-Based Standards for new buildings

• To ensure that a ship meeting these new standards will be recognised by industry as being safe, robust and fit for purpose as would have been required

• To employ the combined experience of all class societies to develop an agreed standard, or set of Rules

IACS Common Structural RulesIACS Common Structural Rules

Net scantling approachNet scantling approach

Buckling and ultimate limit stateBuckling and ultimate limit state of the hull girderof the hull girder

Dynamic loadingDynamic loading

Fatigue lifeFatigue life

Coating lifeCoating life

Transparency and ease of use: Transparency and ease of use: (Under the old rules, the corrosion margin (Under the old rules, the corrosion margin

is given as a percentage, now an absolute min figure corrosion margin)is given as a percentage, now an absolute min figure corrosion margin)

Draft Rules: Draft Rules:

– Fatigue lifeFatigue life [ 25 years ][ 25 years ]

– Coating lifeCoating life [ 10 years ][ 10 years ]

– Corrosion additionsCorrosion additions [ 25 years ][ 25 years ]

– Structural strengthStructural strength intact conditions intact conditions

– Residual strengthResidual strength assumed damagedassumed damaged

Principal new elementsPrincipal new elements

• Net scantling approachNet scantling approach is used throughout the new Rules

• Inclusion of procedures for the assessment of buckling and ultimate limit statebuckling and ultimate limit state of the hull girder

• Inclusion of new methods for describing dynamic dynamic loadingloading

• Inclusion of new methods for determination of the fatigue lifefatigue life

• Development of a Rule format that provides transparency and ease of usetransparency and ease of use

New regulatory frameworkNew regulatory framework

SELF-REGULATION

Safety objectives

Risk acceptance

criteria

Prescriptive rules

Policies, management systems and best practices

Operational requirements

IMO

Goal-Based Standards

Goal-Based FrameworkGoal-Based Framework

Goal Based Safety Objectives

Goal Based Functional Requirements

Goal Based Verification of Compliance Criteria

Tier I

Tier II

Tier III

Industry Standards, Codes of Practice and Safety and Quality Systems for Shipbuilding, Ship Operation,

Maintenance, Training, Manning, etc.

Tier V

IACS Common Rules,

Technical Procedures and Guidelines

Tier IV

IMO

Goal B

ase

d S

tand

ard

sIM

O G

oal B

ase

d S

tand

ard

s

GBS represents the top tiers of framework, against which the ships safety is verified both at design and construction stages and during the operation

MechanismMechanism

The mechanism by which the goal-based

standards will be put in place is:

• IMO sets the goal;

• IACS develops class rules that meet the so-

determined goals;

• Industry and IACS develop detailed

guidelines and recommendations for wide

application in practice.

Goal Based Standards + IACS RulesGoal Based Standards + IACS Rules

Optional sub systems and components

Optional sub systems and components

Detailed rule requirementsDetailed rule requirements

Major systems and equipment

Major systems and equipment

Main shipfunctionsMain shipfunctions

Overall objectives

Fun

ctio

nal R

equi

rem

ent

sG

oals

Rul

es

IMO

Class

Example: Safety ObjectivesExample: Safety Objectives

Goal Based Safety Objectives

Goal Based Functional Requirements

Technical Procedures and Guidelines, IACS Common Rules

Industry Standards, Codes of Practice and Safety and Quality Systems for Shipbuilding, Ship

Operation, Maintenance, Training, Manning, etc.

Goal Based Verification of Compliance Criteria

Tier I

Tier II

Tier III

Tier IV

Tier V

IMO

Goal B

ase

d S

tand

ard

s

Design LifeDesign Life

Environmental ConditionsEnvironmental Conditions

Structural SafetyStructural Safety

Structural AccessibilityStructural Accessibility

Quality of ConstructionQuality of Construction

Example: Functional RequirementsExample: Functional Requirements

Goal Based Safety Objectives

Goal Based Functional Requirements

Technical Procedures and Guidelines, IACS Common Rules

Industry Standards, Codes of Practice and Safety and Quality Systems for Shipbuilding, Ship

Operation, Maintenance, Training, Manning, etc.

Goal Based Verification of Compliance Criteria

Tier I

Tier II

Tier III

Tier IV

Tier V

IMO

Goal B

ase

d S

tand

ard

s

Fatigue LifeFatigue Life

Coating LifeCoating Life

Corrosion AdditionsCorrosion Additions

Strength CriteriaStrength Criteria

Verification CriteriaVerification Criteria

Compliance with the goal-based standards during shipbuildingCompliance with the goal-based standards during shipbuilding

Plan review and approvalPlan review and approval Structural calculationsStructural calculations Surveys during constructionSurveys during construction

Compliance with the goal-based standards on ships-in-serviceCompliance with the goal-based standards on ships-in-service Periodic surveys and thickness measurementsPeriodic surveys and thickness measurements Structural reassessment based on survey and thickness measurementsStructural reassessment based on survey and thickness measurements

DeliverablesDeliverables

• A new complete set of Rule covering the structural requirements for oil tankers and bulk carriers for new construction and for those ships subsequently in service.

• Supporting guidance to amplify the Rules, including the procedures for carrying out direct calculations and for fatigue life assessment.

• Background documents explaining the implicit safety levels, design principles and assumptions on which the Rules are based.

• IACS Common Structural Rules will be in line with the IMO Goal-Based Standards.

Freak Waves FindingsFreak Waves Findings

• Traditionally, this type of waves have been observed Traditionally, this type of waves have been observed

only occasionally under unexpected conditions. only occasionally under unexpected conditions.

However, by virtue of an advance mode of However, by virtue of an advance mode of

measurement and data analysis techniques, such an measurement and data analysis techniques, such an

occurrence is analyzed;occurrence is analyzed;

• Better understanding of the mechanism generating Better understanding of the mechanism generating

such waves has been gained;such waves has been gained;

• The analysis of casualty database and the forecast of The analysis of casualty database and the forecast of

such waves can lead to the development of a such waves can lead to the development of a

mechanism by which masters can be alerted so as to mechanism by which masters can be alerted so as to

enable them to take precautionary action;enable them to take precautionary action;

Freak Waves FindingsFreak Waves Findings

For future study:For future study:

• The design practice is moving a more consistent probablistic The design practice is moving a more consistent probablistic

method, e.g. method, e.g. EExtremes are determined for a given return period xtremes are determined for a given return period

–– expected lifetime of the structure. For consideration in ship expected lifetime of the structure. For consideration in ship

design, the probability of occurrence and also the probability of design, the probability of occurrence and also the probability of

a ship encountering such waves are needed. This involves a a ship encountering such waves are needed. This involves a

rigirous analysis of shipping casualty data. Lack of information rigirous analysis of shipping casualty data. Lack of information

of the core causes of the reported casualties can lead to a of the core causes of the reported casualties can lead to a

misleading or unfounded conclusion. misleading or unfounded conclusion.

• According to the Maxwave study, due to their extreme According to the Maxwave study, due to their extreme

steepness, they last for very short period of time before steepness, they last for very short period of time before

breaking. Hence, the probability of a ship meeting such waves breaking. Hence, the probability of a ship meeting such waves

is even lower that the actual occurrence of freak waves in open is even lower that the actual occurrence of freak waves in open

ocean;ocean;

• SShape of freak wave profiles in space and time including their hape of freak wave profiles in space and time including their

kinematics and ship responses to freak waves are to be kinematics and ship responses to freak waves are to be

documented.documented.

Freak Waves FindingsFreak Waves Findings

• AA distinction between the offshore platform and moving ships distinction between the offshore platform and moving ships

• The validity of a non-linear theory and mathematical model for The validity of a non-linear theory and mathematical model for

freak waves needs be verified. freak waves needs be verified. ENDEND

CSR + GBSCSR + GBS