On 30 Apr 01, at 16:07, Michael Edelman wrote: > I've read a lot about seasocks lately. Some of it seems to be based on > good physics but not necessarily direct experiment. Actually, the theory about the partial vacuum is not good physics. The material of the seasock is so soft it can not cause any pressure difference between the air in the boat and the air in the seasock. The burping does nothing to the air pressure, it only reduces the amount of ait within the boat, and increases the amount of air within the seasock. In order to create a pressure difference you need: - a stiff material that can be loaded in bending (pressure vessel) -or flexible material that is loaded in tension (blown up balloon) The seasock is a flexible material, bot not loaded in tension unless you would burp it by vacuumising the interior of the boat using a pump. Greetings, Merijn > ************************************************************************** > * 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/ > ************************************************************************** > * ****************************** Merijn Wijnen Vinkenhofje 8 5613 CN Eindhoven The Netherlands Tel.: 040-2939991 (job: 040-2650539) Fax: same as tel., call before sending or try twice E-mail: Home: merijn_at_music.demon.nl Job: m.wijnen_at_ind.tno.nl Web-site: http://www.music.demon.nl *************************************************************************** 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/ ***************************************************************************
Merijn, you said: "Actually, the theory about the partial vacuum is not good physics. The material of the seasock is so soft it can not cause any pressure difference between the air in the boat and the air in the seasock. The burping does nothing to the air pressure, it only reduces the amount of ait within the boat, and increases the amount of air within the seasock." How would you explain the seasock retention, in good terms of good physics? I've noticed an interesting, perhaps related phenomenon lately. I now have a drytop, latex seals at neck and wrists. I tighten the waist bungy as far as bearable. If a little water gets into the cockpit, say from re-enter and roll practice, I then pump it out with a foot pump. As the water is pumped out, the spray deck depresses, and the cag starts to cling like shrink wrap on me! I then let in a little air by releasing the spray deck at the side of the coaming. If you can vacuum bag a boat, you can vacuum bag a paddler! Regards, Peter Treby 37º 42' S 145º 08' E *************************************************************************** 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/ ***************************************************************************
Hi Peter, > "Actually, the theory about the partial vacuum is not good physics. > The material of the seasock is so soft it can not cause any pressure > difference between the air in the boat and the air in the seasock. > The burping does nothing to the air pressure, it only reduces the > amount of ait within the boat, and increases the amount of air within the > seasock." How would you explain the seasock retention, in good terms of > good physics? It is quite simple: The amount of air in the boat is defined by the volume of the cockpit minus gear volume, this amount of air is constant. Using a seasock you split the air within the boat in two parts: between boat and seasock, and within the seasock. By burping the seasock you move air from between boat and sock to within the sock. After the sock is fixed on the coaming no air will enter the room between boat and sock, so the sock will stay of you. It is a bit like I've noticed an interesting, perhaps related phenomenon > lately. I now have a drytop, latex seals at neck and wrists. I tighten the > waist bungy as far as bearable. If a little water gets into the cockpit, > say from re-enter and roll practice, I then pump it out with a foot pump. > As the water is pumped out, the spray deck depresses, and the cag starts > to cling like shrink wrap on me! I then let in a little air by releasing > the spray deck at the side of the coaming. If you can vacuum bag a boat, > you can vacuum bag a paddler! Actually, if you use a seasock in a hardshell with footpump this would be a very effective way of burping the sock, if you let some air into the seasock through the tube of you spray skirt. Greetings, Merijn > > Regards, > Peter Treby > 37º 42' S 145º 08' E > > > > > ************************************************************************** > * 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/ > ************************************************************************** > * ****************************** Merijn Wijnen Vinkenhofje 8 5613 CN Eindhoven The Netherlands Tel.: 040-2939991 (job: 040-2650539) Fax: same as tel., call before sending or try twice E-mail: Home: merijn_at_music.demon.nl Job: m.wijnen_at_ind.tno.nl Web-site: http://www.music.demon.nl *************************************************************************** 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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