The research underpinning the book was initiated by a group of OCIMF member companies, the American Institute of Merchant Shipping (AIMS) and the International Salvage Union (ISU). The British National Maritime Institute (NMI) was commissioned to carry out intensive model testing with free floating and tethered models that was validated with full scale drift data obtained from a number of vessels, predominantly VLCC's but also some smaller tankers.
1. Introduction
1.1 Purpose of Investigation
1.2 Details of Models
1.3 Synopsis of Experiments and Computations
2. Experiments with Free Models
2.1 Description of Experimental Method
2.2 Calculation Wind Forces and Moments
2.3 Arrangement of Test Series
2.4 Results: Twin-Screw Model 5481
2.4.1 Free-Drift Experiments
2.4.2 Manoeuvring with Limited Power Available
2.4.3 Manoeuvring with Rudders Flying Free
2.5 Results: Bulbuos-Bow Model 5480A
2.5.1 Free-Drift Experiments
2.5.2 Manoeuvring with Limited Power Available
2.5.3 Manoeuvring with Rudder Flying Free
2.5.4 Effect of Heel with Power Available
2.5.5 Force to Move Model out of Trough
2.5.6 Wind and Waves from Different Directions
2.6 Results: Rounded Bow Model 5480B
2.6.1 Free-Drift Experiments
2.6.2 Manoeuvring with Limited Power Available
2.6.3 Manoeuvring with Rudder Flying Free
2.6.4 Effect of Heel with Power Available
2.6.5 Force to Move Model out of Trough
2.6.6 Wind and Waves from Different Directions
2.7 A Note of Coriolis Effects
2.8 Summary of Main Conclusions
2.8.1 Free-Drift
2.8.2 Controlled Drift
2.8.3 Towing Forces to Head into Weather
3. Measurements of Drift Forces in Waves
3.1 Experiment Arrangement
3.1.1 Introduction
3.1.2 Programme of Tests
3.1.3 Sea-State Spectra
3.1.4 Mooring Arrangements
3.1.5 Force Measurements
3.1.6 Instrumentation
3.1.7 Conduct of the Tests
3.2 Results Obtained
3.2.1 Method of Presentation
3.2.2 Accuracy and Repeatability
3.2.3 Effect of Wave Encounter Angle
3.2.4 Effect of Seastate
3.2.5 Effect of Rudder
3.2.6 Effect of Hull Shape
3.2.7 Effect of Trim
3.3 Conclusion
4. Calculations of Drift Forces in Waves
4.1 Introduction
4.2 Method of Calculation
4.3 Ship Models
4.3.1 Model 5480B
4.3.2 Modified Model with L/B=4.5
4.3.3 Natural Periods
4.4 Spectral Model
4.5 Numerical Models
4.6 Results
4.6.1 Regular Waves
4.6.2 Irregular Waves
4.7 Comments on Results
4.7.1 Regular Waves
4.7.2 Irregular Waves
4.8 Comparisons between Calculated and Measured Results
5. Conclusion
6. References
The Oil Companies International Marine Forum (OCIMF) is a voluntary association of oil companies (the ‘members’) who have an interest in the shipment and terminalling of crude oil, oil products, petrochemicals and gas. OCIMF’s mission is to be the foremost authority on the safe and environmentally responsible operation of oil tankers, terminals and offshore support vessels, promoting continuous improvement in standards of design and operation. Learn more at www.ocimf.org