On the assessment of parametric roll in random sea

Jørgen Juncher Jensen, Anders Smærup Olsen

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


The aim of the present paper is to advocate for a very effective stochastic procedure, based on the First Order Reli-ability Method (FORM) well-known within structural reliability. Due to the efficient optimisation procedures imple-mented in standard FORM codes and the short duration of the time domain simulations needed (typically 60-100s to cover the structural memory effects in the response) the calculation of the upcrossing rate of a given level of the re-sponse is very fast. Thus complicated non-linear effects can be included. An application for roll motions of ships will be discussed. A simple non-linear dynamic model for roll including the effect of heave is formulated in the time domain. Closed form expressions are used for the heave motion and for the wave-induced roll moment. The instantaneous GZ curve is derived numerically, but only for one regular wave. Inclu-sion of parametric roll in the example has not been possible due to shortcomings in the present model of the GZ curve and the lack of a coupling to pitch. However, provided more accurate hydrostatic and hydrodynamic models are used, parametric roll could be accounted for, too, in the proposed stochastic procedure.
Original languageEnglish
Title of host publicationWorld Maritime Technology Conference
Place of PublicationLondon, UK
PublisherIMarEST Publications
Publication date2006
Publication statusPublished - 2006
EventWorld Maritime Technology Conference 2006 - Queen Elizabeth II Conference Centre, London, United Kingdom
Duration: 6 Mar 200610 Mar 2006


ConferenceWorld Maritime Technology Conference 2006
LocationQueen Elizabeth II Conference Centre
Country/TerritoryUnited Kingdom


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