Yachting's next revolution?


 
We look at Hugh Welbourn's Dynamic Stability System - a lateral retractible foil to leeward...
The yachting world is on the verge of its next significant revolution with a new invention that adds stability when sailing. Over the last decades keels have got deeper, their weight concentrated in a lead bulb at their extremity. Water ballast systems have since allowed sea water to be pumped into tanks up to weather, at times adding more than 50% to the displacement of the boat. This allowed bulbs to get smaller and overall displacement to be reduced when unballasted, but has the downside of requiring displacement to increase substantially (as the water ballast is pumped on board) when additional righting moment is required – not the best solution off the wind or in a moderate sea state. Canting keels, where the bulb is cranked up to weather (first introduced in the Mini class in the early 1980s and adopted by the Open 60s over the course of the 1990s) neatly solved this inherent weakness of water ballast. Since then centreline water ballast tanks have appeared on canting keel Open 60s, used to alter overall displacement and to adjust fore and aft trim. While a canting keel and centreline water ballast configuration ticks most of the boxes in terms of achieving a boat that has a mode for every point of sail, wind strength and sea state, this set-up still has its downsides. There are several aspects of a canting keel/centreline water ballast set-up that are plain inefficient. For example the canting foil in this set-up should perhaps be more accurately described as a ‘strut’, as all it does is hold the bulb out to weather. Its function of providing lift and preventing leeway, as it would on a fixed keel boat, is vastly diminished when canted and so something must be fitted to compensate – and in the majority

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