PeterO wrote: > > But its not at all clear or intuitive why different boats may turn in one > direction or another when edged on one side only? And I doubt that I'm alone > in not understanding this even qualitatively. > > I'ld be very appreciative of an explanation or a reference! Are there any > standard texts that treat this subject? > This has to do with the unbalanced forces around the center of gravity. As the boat heels the under water hull changes shape. How it changes shape determines the direction of turning. I know of no easy and simple way to predetermine this since it involves many variables. For example, lifting forces, drag forces, and shifts in the center of gravity. The math gets pretty complex. If you are really keen on this kind of thing I suggest starting with Principles of Naval Architecture published by the Society of Naval Architects and Marine Engineers. You need only purchase the volume on Controllability (Vol #2 I think. I am at work and do not have it handy to check that) It has a list of technical papers dealing with specific problems. You will have to do some mental gymnastics with all of this since the research focussed on ships and sailboats. The principles remain consistent though so if you can manage the math you should find the rest understandable. I found the sailboat stuff most valuable since controllability when heeled means so much in sailing. Many theories about this have surfaced over the years. One famous one, the Metacentric Shelf Theory actually produced boats with excellent course stability over a wide range of conditions. The Colin Archer type cruising boats were designed using this theory I think. Later research proved that they worked for other reasons so it looks like you can do the right thing for the wrong reasons. :) It also turned out you could produce boats with poor directional stability using the Metacentric Shelf Theory. You can test this kind of thing best in a tank where you can easily measure the forces involved in a controlled setting. Not sure you can do it reliably in real life. Cheers, John Winters *************************************************************************** PaddleWise Paddling Mailing List - Any opinions or suggestions expressed here are solely those of the writer(s). You must assume the entire responsibility for reliance upon them. All postings copyright the author. Submissions: PaddleWise_at_PaddleWise.net Subscriptions: PaddleWise-request_at_PaddleWise.net Website: http://www.paddlewise.net/ ***************************************************************************
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