Date: Thu, 23 Jul 1998 10:42:34 -0700 (PDT)
Message-Id: <199807231742.KAA01840@ns.intelenet.net>
To: baidarka@lists.intelenet.net
From: redcanoe@pangea.ca (Douglas Ingram)
Subject: Re: [baidarka] Paddles
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.
Each hull has a theorectical maximum hull speed. that point is reached when
the bow wave created has a wavelength matching the length of the hull.
After that, you are paddling "uphill". It is possible to cheat a little by
having a bow that can cut through the bow wave crest by being very skinny,
and having a stern which doesn't squat (much), at the same time having a
nice clean waterline. Returning the medium after the passing of the boat
consumes more energy than the parting of it.
As for the paddles, consider these points:
-deeper water is more "solid" than surface water. Getting your paddle in
deeper will provide more forward thrust for the same effort, than working it
only in the slippery surface water, which slides back with each stroke.
Look for whirlpools, and avoid them as evidence of slippage. Look for
paddle blade shapes which allow you to do this. There will be more load at
the tip of the paddle, down deep, than there will be near the throat, so it
doesn't need to be as big.
-big strong strokes consume a lot of energy. They also cause the canoe to
push up the bow wave in one big effort, and then slow down as you prepare
for the next big strong stroke. You will find it more restful to take
shorter strokes, concentrating your efforts in the power phase of the
stroke, and having a short recovery. This will make your work less
strainful at any given time, as well as maintaining a more constant speed
through the water.
-big blades slow down your stroke rate as it takes more effort to get a good
stroke, blades which are too small make you feel like a windmill.
-one of the factors which affect aboriginal paddle design is in fact the
sound that they make while in use, That way a person could identify the
group membership of the user without ever seeing them. I just finished some
work on a couple of canoe paddles, one from Panama, and the other from
Guyana. This was exactly the case with those paddles.
>Gene Smith wrote:
>>
>> Anybody know of any hydrodynamic studies of paddles - both single and
>> double? Some recent paddling has convinced me that there is a point where
>> paddling harder adds a great deal more to energy expended than it does to
>> thrust. I'm curious to know if any studies have been done to try and
>> pinpoint the area of maximum paddling efficiency.
>
>What you describe has much more to do with increase of friction and wave
>resistance. Take any issue of sea kayaker and read the numbers in kayak
>essays, and you will see that resistance increases geometrically with
>speed.
>
> I'd also like to know
>> more about the paddle designs of indigenous peoples - they seem often to be
>> very different than the shapes I am used to seeing in modern use. Any
>> clues?
>
>paddles in many cultures were not seen as mere propulsion, but also had
>to serve different needs (silence of operation when hunting or
>approaching the enemy for example). In the western coast of Africa I've
>seen many paddles shaped like pointed hart shaped leaves. Very pointed,
>and the extremities were often let dragging in the water to avoid noise
>from dripping water. Pointed enough to be quite offensive tool.
>
>This is all I know... Stefano
>> Gene Smith
>
>
>
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