Date: Fri, 24 Jul 1998 09:10:17 -0700 (PDT)
Message-Id: <199807241610.JAA09502@ns.intelenet.net>
To: baidarka@lists.intelenet.net
From: redcanoe@pangea.ca (Douglas Ingram)
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
Rough skins on canoes and kayaks are usually the result of scratches and
roughness such as all those tiny fibres from the canvas poking out and
creating additional surface area, rather than the uniform micro roughness of
a shark skin, or those fancy bottom paints which cause a very small
turbulence at the interface which creates an even more slippery surface.
Douglas Ingram
Red River Canoe & Paddle
P.O. Box 78, GRP 4, RR 2
Lorette, Manitoba
Canada
ROA OYO
(204)878-2524
URL: www.wilds.mb.ca/redriver
e-mail: redcanoe@pangea.ca