Brian wrote; (SNIP) : > > Wouldn't providing enough initial stability to enable reentering require > increasing the beam so much as to reduce final stability to the point that > capsize in the first place could conceivably be more likely? > > Not necessarily. Stability is obtained in four basic ways. 1. Lowering the CG. 2. Increasing displacement 3. Increasing waterplane area. 4.Increasing beam. The first and second do not increase the capsizing moments in rough water and favorably increase the stability range. The third does not have to increase the capsizing moments so much as increasing beam since it can be done while retaining narrow beam. In addition it is also possible to shape the hull in such a way as to increase the stability range (secondary stability) without increasing initial stability. Usually this is accomplished through flared topsides. Dan wrote; > How would this make sponsons redundant? Forgive me if I am a bit slow, > but I really do not understand your point. Of course one could design a > boat which, due to it's substantial beam, always has the same stability > as Boat X with sponsons deployed. But the problem with such an approach > is that you cannot reduce the beam for those times when a less beamy > boat is desired. With sponsons you can increase the beam *temporarily* > for the purpose of taking a crap or a nap (or whatever), and then reduce > the beam once it is time to paddle. How do you intend to achieve this if > the boat is beamy to begin with? Personally, I do not like the feel of > beamy boats, but I do like the option of temporarily increasing the > beam. As always, this is just my humble opinion. You are not slow. Stability takes up a large portion of most naval architecture books and is an extremely complicated topic. The nature of stability changes as the boat heels beyond seven to ten degrees and what seems good at low angles of heel is not good at high angles of heel. More importantly the nature of stability provided by form differs from that provided by displacement and CG location. I hope the response to Brian's question clears that up a bit. My suggestion was not that everyone should have any type of boat. It was that there are other ways of skinning this cat. They will not please everyone just as no one boat will please everyone. Sponsons are one method of solving certain problems but they aren't the only solution or maybe not even the best solution for some types of paddling or paddlers. The introduction of another solution should not be construed as a criticism of any solution but rather the introduction of another possibility that may be "better" for some one. We have heard here from people who do wet re-entries into narrow boats without any assist. Some might prefer to put ashore for a nap. Some have clever methods of handling bodily functions. Some use paddle floats . If one likes sponsons and finds them useful then that is good. My concern has always been that most people do not understand or are unaware of the downside of things. I know of no rescue device or technique that is fool proof or 100% reliable or does not have some aspect that will turn off at least one paddler. I have attended SNAME (Society of Naval Architects and Marine Engineers) symposia where people with more letters behind their names than I have in mine argue over these things. :-) Cheers John Winters Redwing Designs Specialists in Human Powered Watercraft http://home.ican.net/~735769/ *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net ***************************************************************************
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