BASIC STATISTICAL UNCERTAINTIES IN PREDICTING EXTREME SECOND ORDER SLOW DRIFT MOTION

Significant statistical variation is observed between different sub-records of a long (18 hours) slow-drift motion record obtained in 1:70 model tests. The scatter is observed in extreme values as well as in standard deviation and spectra of the signal A theoretical model, based on the classical Gumbel approach combined with existing results on extreme slow-drift behaviour, predicts around twice as much extreme value scatter for 2nd order slow-drift processes as for linear Rayleigh distributed processes. This basic statistical variability may well explain the experimentally observed scatter. The theoretical model predicts increased scatter with increased slow-drift motion damping. Results from numerical simulation on expected extremes with scatter are presented. Apart from some discrepancies for very high and very low damping, these results compare reasonably well with the theoretical model.

• Supplemental Notes:
  • ISOPE 1992, 2nd Intl Offshore & Polar Engng Conf; 14-19 June 1992; San Francisco, USA. Sponsored by Intl Soc Offshore & Polar Engrs (ISOPE) et al. Procs. Pubs by ISOPE, ISBN 1-880653-03-6. Vol III, p 526 [6 p, 8 ref, 6 fig]
• Authors:
  • Stansberg, C T
• Publication Date: 1992

Language

• English

Subject/Index Terms

• TRT Terms: Drift; Mathematical models; Motion; Statistical analysis
• Uncontrolled Terms: Numerical models
• Old TRIS Terms: Drift forces
• Subject Areas: Data and Information Technology; Marine Transportation;

Filing Info

• Accession Number: 00706301
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM