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What do we face in the design?
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Existing Tanker Fleet
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World 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
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A new type of VLCC is Born
MALACCA-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 !
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Double vs Single Hull Tankers
• Increased Strength Requirements
• Increased Stability Requirements
• Increased Cargo Temperature
• Increased Ballast Surface
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Structural Design Considerations
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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 ND
Computer 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 by
POSEIDON-Plating
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It is not over yet!
2nd Stage of Analysis Æ 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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Sloshing
Critical for:
Ltank>0.1L and/or Btank>0.5B
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Slamming
Critical at Low Draft Fwd-High Speed
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Fatigue Assessment
Critical 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 Details
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Design Proper Structural Details !
Quiz:Find what is missing below
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LAST BUT NOT LEAST
Operational 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
Overall frequencyweighted r.m.s.values
from1 to 80 Hz
A
Passenger Cabins for
instance
mm/s
mm/s2
Area Classification
B
CrewAccommo
dation for instance
mm/s2 mm/s
C
Working Areas
for instance
mm/s2 mm/s
Values above which
adverse comments
143
4
214
6
286
8
are possible
Values belowwhich
adverse comments
71.5
2
107
3
143
4
are not probable
Note: The zone between upper and lower values reflect the shipboard vibration environment
commonly experienced and accepted
• Vibration Level Prediction
• Analysis of coupled
machinery/foundation
vibrations
• Vibration measurement
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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!
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