Robert wrote; (SNIP) > >I don't know about boat hulls, but with airplane wings, a rough surface, >such as clear and especially rime icing not only increases the coeficient >of resistance (called drag) it completeley destroys the lift capacity of >the wing. A little roughness on the surface destroys the laminar flow... >In other words... it won't fly. I would suspect that a boat hull might be >similarly, although not as drastically, effected. I mean, it is not going >to sing. However, it is not the resistance that is so critical with the >wing, but the destruction of laminar flow. The question is John, does this >analogy apply to the boat hull and is the 3% therefore, worse than it >sounds? No. In the case of the airplane the loss of lift is the serious part not the drag. In the boat case it is just more drag. Laminar flow only exists over a very short portion of the boat (rarely more than a foot or two) due to the constant yawing, particulate in the water, wave action, pitching, surging etc. The increase I quoted is for an increase over the normal turbulent flow condition existing for a hydrodynamically smooth surface. Note this is turbulence in the boundary layer and not eddy making that may occur at the stern. 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/ ***************************************************************************Received on Wed May 27 1998 - 03:54:35 PDT
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