An investigation into the self-righting of a modern racing yacht in waves

Ocean sailing yachts can, and do, capsize from time to time, and so the saf ety of those who sail on them is linked directly to their ability to self-r ight once capsized. Current regulations used for racing yachts are based on statical concepts, which have been shown to be inappropriate (Renilson et al 2000). In order to gain an understanding of the dynamic factors involved , experiments were conducted on a 1/12.5 scale model of an ocean sailing ya cht in waves in the towing tank at the Australian Maritime College. Two dif ferent experimental procedures were developed: Testing in a single breaking wave, and testing in steep irregular waves. Four variations of the limit o f positive stability were tested, together with one condition which had a d ifferent roll radius of gyration, without water on board the model. In addi tion, two variations of the limit of positive stability were tested to repr esent the condition with 4000 kg of water on board. From the tests it was p ossible to conclude that, for the given yacht, if the limit of positive sta bility is decreased from 119 deg to 104.7 deg the yacht is much less likely to self-right under the action of waves, with or without 4000 kg of water on board.