>The subs' speed will determine the amount of >energy to be dispersed. Unless the bottom (and sides) of the basin the sub >is in can disperse the energy from the pressure in front of the sub it would >seam that it would eventually (how soon is unclear but given the >incomressible nature of water I would think it would have to happen very >quickly) end up at the surface and be used to lift some water above the >level of the surface creating waves whether they be detectible or not. For what it is worth is worth, "The modern submarine experiences no wave-making resistance whatsoever when submerged more than three diameters from the free surface". (Thomas Gilmer, "Introduction to Naval Architecture", the text book for naval architecture at the U.S. Naval Academy.) >On the other hand maybe no wake is really necessary as the pressure at the >bow and the lower pressure at the stern may just mean the water moves faster >over the hull to fill in the low pressure area behind the sub balancing the >system. Most hydrodynamicists call this form resistance. Scragg and Nelson studied form resistance on rowing shells and worte an interesting paper on this. >Back when I was trying to understand weatherhelm I looked in a lot of books >and while many of them mentioned it and some even described how ships add >funnels and such forward to compensate none of the books I found gave an >expanation and I had to devise my own. H. Eda has published at least ten papers on this that have provided me with a lot of help. Also, Nomoto's "Balance of Helm of Sailing Yachts" can prove useful and "Principles of Naval Architecture" also provides good background. (SNIP) 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 Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
At 7:29 AM -0400 6/3/99, John Winters wrote: >>The subs' speed will determine the amount of >>energy to be dispersed. Unless the bottom (and sides) of the basin the sub >>is in can disperse the energy from the pressure in front of the sub it >would >>seam that it would eventually (how soon is unclear but given the >>incomressible nature of water I would think it would have to happen very >>quickly) end up at the surface and be used to lift some water above the >>level of the surface creating waves whether they be detectible or not. > >For what it is worth is worth, "The modern submarine experiences no >wave-making resistance whatsoever when submerged more than three diameters >from the free surface". > >(Thomas Gilmer, "Introduction to Naval Architecture", the text book for >naval architecture at the U.S. Naval Academy.) I will accept no _measurable_ wave-making resistance whatsoever. Physics does not generally work with forces disappearing all-together, they instead get to be so small that you can ignore them completely. The equation for wave velocity has depth as one factor. There is no theoretical limit to this depth having a calculatable effect on wave velocity, but there is a practical limit where you can say "if the depth is greater than a certain number of wavelengths, you can ignore it." I went swimming yesterday, and as I did my breaststroke across the lake, I watched as I pushed my hands in front of me at different depths. Close to the surface, there was a distinct wake and I could feel the drag. When I pushed my hands forward at lower depths, the wake and drag decreased. With my very course measurement apparatus, at about 2 radi was deep enough that I couldn't detect a wake or a change in drag. Nick Schade Guillemot Kayaks 10 Ash Swamp Rd Glastonbury, CT 06033 (860) 659-8847 Schade_at_guillemot-kayaks.com http://www.guillemot-kayaks.com/ >>>>"It's not just Art, It's a Craft!"<<<< *************************************************************************** PaddleWise Paddling Mailing List Submissions: paddlewise_at_lists.intelenet.net Subscriptions: paddlewise-request_at_lists.intelenet.net Website: http://www.gasp-seakayak.net/paddlewise/ ***************************************************************************
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