25.05.20052003-12-10

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What do we face in the design?

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Existing Tanker Fleet

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World Oil MovementsWorld Oil Movements

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Oil Tanker Categories

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Principal Dimensions of Tankers I

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Principal Dimensions of Tankers II

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Principal Dimension Considerations

• Breadth Limitations (Panama Canal)

• Draft Limitations (Trade Route)

Suez Canal

Malacca Straits

25.05.20052003-12-10

A new type of VLCC is BornMALACCA-MAX

T=20.5m Cargo same as a large VLCC

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Double vs Single Hull Tankers

• We have come a long way !

25.05.20052003-12-10

Double vs Single Hull Tankers

• Increased Strength Requirements

• Increased Stability Requirements

• Increased Cargo Temperature

• Increased Ballast Surface

25.05.20052003-12-10

Structural Design Considerations

25.05.20052003-12-10

Structural Design Considerations

• Longitudinal Strength (Global Bending/Shear)

• Transverse Strength (Primary Support Members)

• Buckling (In combination with above)

• Fatigue (Long Term Effect)

• Ultimate Strength (Extreme Load/Plasticity)

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Longitudinal Strength (Beam Model)

• Minimum Section Modulus (IACS Requirement)

• Static and Wave induced Bending and Shear

• Sagging and Hogging

• Sagging dominates in Full Load

• Hogging dominates in Ballast Load

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Transverse Strength (Local Loads)

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Typical Midship Section of a VLCC

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More Mid-ship Sections

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How to do it? Cavalry To the Rescue!

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POSEIDON NDComputer Supported Tanker Scantling

Assessment

• Rule Based Structural Design

• First Principle Structural Design

• Support of Plan Approval Procedure

• Condition Assessment

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Midship Section of a Suezmax Tanker Created byPOSEIDON-Plating

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It is not over yet!2nd Stage of Analysis FEA

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Model of a Suezmax Tanker without Deck and Shell Plating

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FE Model 319,000 dwt VLCC

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The bad and the ugly:Sloshing and Slamming

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SloshingCritical for:

Ltank>0.1L and/or Btank>0.5B

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SlammingCritical at Low Draft Fwd-High Speed

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Fatigue AssessmentCritical AreasCritical Areas

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Fatigue Input (In addition to Stresses)Wave Scatter

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Material Tolerance (S-N curves)

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Detailed Stress Analysis (Zooming)

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In Conclusion of Fatigue 101

• Miner Damage Accumulation Model

• North Atlantic Wave Input

• Weibull Stress Distribution

• Proper S-N curves (depend on approach)

• Satisfy Target Life (>20 years)

BUT…………

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The Fatigue Doctor: Good DetailsThe Fatigue Doctor: Good Details

25.05.20052003-12-10

Design Proper Structural Details !Quiz:Find what is missing below

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LAST BUT NOT LEASTOperational Considerations in Design

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Ship Acoustics

• Noise prediction

• Optimisation of engine foundations

• Optimisation of structure-borne noise insulation index

• Noise measurements

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Vibrations

• Local Vibration Analysis

• Mast Vibration Analysis

• Shaft Vibration Analysis

• Vibration Level Prediction

• Analysis of coupled machinery/foundation vibrations

• Vibration measurement

Area Classification A

Passenger Cabins for instance

B Crew Accommo

dation for instance

C Working Areas for instance

Overall frequency- weighted r.m.s.-values from 1 to 80 Hz mm/s2 mm/s mm/s2 mm/s mm/s2 mm/s Values above which adverse comments are possible

143

4

214

6

286

8

Values below which adverse comments are not probable

71.5

2

107

3

143

4

Note: The zone between upper and lower values reflect the shipboard vibration environment commonly experienced and accepted

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The Big Enemy: Corrosion!

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Coatings do not last forever!

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Protection of Cargo Oil Tanks

• Pitting corrosion caused by sulphur components in combination with water

• Formation of hydrochloric acid

• Sulphur reducing bacteria

• Susceptible areas to be protected by coatings

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Where to Protect?

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Do not Forget : Eco-friendliness

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THANK YOU FOR YOUR ATTENTION!