Capsize Risk Assessment Using Fredyn Ship Motion Predictions
Abstract
This report presents a method for predicting capsize risk of intact ships in a seaway. Ship speed and heading are assumed to be independent variables, and the joint distribution of significant wave height and peak wave period is obtained from a wave scattergram. For a given set of operating and environmental conditions, the time domain program Fredyn is used to determine the occurrence of ship capsize. For irregular seas, the dependence of capsize on wave process realization is modelled by fitting a Gumbel distribution to maximum absolute roll angles obtained from several different wave phase seed numbers. Ten simulations of 30 minute duration can adequately provide the distribution of maximum hourly roll angle for a given seaway and ship operating condition. Sample computations for a Canadian Patrol Frigate suggest that the method gives realistic estimates of annual capsize risk. The current implementation conservatively assumes that ship speed and headings are independent of wave conditions. Future work will examine ship operational profiles to include the influence of capsize avoidance action.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1999
- Accession Number
- ADA375836
Entities
People
- K. A. Mctaggart