Trans RINA, Vol 153, Part B2, Intl J Small Craft Tech, 2011 Jul-Dec


Examination of the data relating to classes of which six or more took part in the race clearly suggests that a high proportion of boats that suffered a B.2 knockdown were subsequently abandoned. A simplistic parametric analysis of the main particulars of the boats did not identify


any behaviour.


There were distinct indications that the more recent designs developed under the IOR Rule (more beamy, lighter and with higher centre-of-gravity) were more vulnerable to inversion than older designs.


3. POST-FASTNET INVESTIGATIONS


3.1 Wolfson Unit Research 3.1 (a) Introduction


In 1983 an investigation to determine what properties of sailing yachts are most likely to be associated with their


pronounced correlation with capsize


propensity to capsize in large undertaken at


Southampton


breaking waves was University


[3]. The


programme was divided into two parts comprising a hydrostatic evaluation of existing craft designed over the preceding 20 years, and an experimental phase in which a systematic series of models were subjected to tests in large breaking waves in the towing tank.


The first phase showed a pronounced tendency for the maximum righting moment and AVS to reduce between 1960 and 1980 (by 50% and 30% respectively). AVS is the heel angle beyond which a boat will invert. At the same time the positive area under the righting moment curve (a measure of the energy required to capsize in calm water) reduced, and the negative area (a measure of the energy required to right the boat from the inverted condition) increased. Clearly these trends


were


increasing the probability of more modern yachts having a slow recovery after an inversion.


Figure 1: Hull forms of models tested (taken from [2 & 3])


B-96


©2011: The Royal Institution of Naval Architect


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