Date: Fri, 24 Jul 1998 10:49:14 +0200
From: Stefano Moretti <S.Moretti@agora.stm.it>
To: baidarka@lists.intelenet.net
Subject: Re: [baidarka] Paddles
Douglas Ingram wrote:
>
> Skin friction is not to be discounted in understanding the paddling
> efficiency of a canoe or kayak. John Winters has some nice data which show
> that, for canoes at least, the amount of skin drag exceeds the speed
> benefits of increased length at about 16.5'. Also inportant is keeping the
> skin of the canoe/kayak smooth, a rough skin caused either as the result of
> abrasion or lack of proper preparation and application, can DRAMATICALLY
> affect skin friction.
Doug, somebody should advise EVOLUTION that after several dozen million
years still hasn't acknowledged this fact, providing sharks and other
marine animals (Celacanthus etc) with coarse skins+ mucus. Skins that
in many cultures are still used as powerful abrasives when dry.
Same with fast driven hulls that are painted with hygrophyle (sorry for
spelling) bottom paint to reduce viscosity by providing water-water
interface.
Be as it may, water flux along a hull is anything but laminar in the
real world (water).
Stefano