Re: [Paddlewise] (un)Feathered paddles in surf

-----Original Message-----
From: John Winters <735769_at_ican.net>
To: paddlewise_at_lists.intelenet.net <paddlewise_at_lists.intelenet.net>
Date: Thursday, April 29, 1999 5:30 AM
Subject: Re: [Paddlewise] (un)Feathered paddles in surf


>>Matt wrote;>>
>
>-(SNIP)
>
>
>>Paddling across a very strong wind a feathered paddler needs to be careful
>>not to raise the blade too high or the wind can catch under it. This is
>easy
>>to compensate for and once the danger was recognized I never had to let go
>>of the upper blade (or twist it to spill the wind) again even in exteme
>side
>>winds. I will speculate that if one had to do a quick brace as a side wind
>>gust pushed you of balance, reactions rather than reason would take over
>and
>>you might well find yourself doing a sudden high brace. Now the
>unfeathered
>>blade would be inadvertently exposed to the high wind. This would tend to
>>counteract the brace, pushing you further over to the side you from which
>>you are already trying to recover.
>
>John Winters answered:>
>Possible I suppose but I never had that experience. I have had problems
>with twisted blades in beam winds. Perhaps one just learns to live with the
>problem which ever one you have.
>

>>Letting go of the paddle with one hand
>>(or twisting the shaft to spill the wind) won't be able to help you here.
>>Blade speed is roughly 2.5 times boat speed. A paddler paddling 4 knots
>into
>>a 10 knot wind would have (4 x 2.5) ten knots of additional paddle blade
>>speed to add to the wind speed (and doubling the relative wind creates 4
>>times the resistance).
>
>I think this may have an element of exageration. Parallel flow (to the
>water and hence normal to the blade) rarely occurs. Surface turbulence and
>the altered flow around the paddler can cause the flow around the blade to
>approach being parallel to the blade. Obviously this varies with the
>altitude of the blade etc. but in any case one cannot simply assume that
>the flow strikes the blade at anything near normnal to the surface.  Such
>and approximation needs more study before applying it without reservations.


True, but I doubt way out at the paddle blade (at least when it is at the
angle most effected by the wind) ones body has much effect. Thinking about
this possibility a little more: it would seam that you are helping my
argument here. Since the paddle is most effected when it is perpendicular to
the wind and since one paddles with the paddle out in front of the body, if
the flow is altered by the body way out to the paddle blades it is more
likely to be deflected at the paddle blade when the wind is from behind the
body and the paddle is therefore further downwind. Since an unfeathered
paddle is also deflecting the wind it is possible (especially near the end
of a stroke) that the upper blade (angled forward like a scoop) is
deflecting some wind into the paddlers wind catching body to some extent and
this might further slow the paddler down.

>Of course,  one must also factor in the height of the stroke. The
>traditional paddle users generally use lower strikes where the wind has
>much less effect anyway.

The feathered paddler also uses a lower stroke when desireable such as in
strong side winds. Of course, there is some loss of efficiency with a lower
stroke because the blade is sweeping in an arc and is futher from the
centerline of the kayak and spends less time at the most effective angle,
but sometimes the benefits are worth it.

>
>Sailors will have some familiarity with the altered air flow around a body
>(safe leeward effect) etc.
>
>>Turning around and ignoring that you would be moving
>>faster downwind for the same effort (which is working even more in my
>>arguments favor) a blade moving at 10 knots downwind in a ten knot
>following
>>wind would gain no benefit from the wind. At best the penalty for
>>unfeathered into the wind is far greater than any benefit garnered going
>>downwind.
>
>The pressure against the blade varies with relative velocities. Since the
>blade doesn't always travel parallel with the air flow (the blade travels
>in a roughly elliptical path or sometimes egg shaped path depending upon
>stroke mechanics) and much of the time its relative velocity is much lower
>than the approximation Matt used.
>
True again, but since the blade angle is also smaller at that time so is the
effect of the wind on it then. I expect whoever we tempt into figuring out
the added drag into a headwind due to using an unfeathered paddle will take
the time the blade spends at various angles to the wind into account.


>
>Having developed rather painful wrist problems from using feathered blades
>and having "cured" them using an unfeathered blade I suspect that the
>benefits of one over the other may have more to do with treating the paddle
>and paddler in a holistic manner rather than as isolated benefits and
>drawbacks.

The way feathered paddling is usually taught is a perscription for wrist
problems and while paddling unfeathered is one cure pushing with a straight
wrist and a somewhat open hand also works and doesn't have the disadvantages
of unfeathered paddling (and those due to switching feathers on bracing
skills) to contend with.
>
>The feathered paddle (in my case) has much less efficiency than the
>unfeathered paddle. No doubt some one will say, "You just didn't use the
>right stroke mechanics" and no doubt that would have an element of truth
>but maybe it works both ways.

How did you judge which was most efficient for you? Were you bending your
"control hand" wrist back on the feathered push? Do you think you can
convince top racers that if they switch to unfeathered they will be more
efficient? I can't believe that Olympic teams haven't looked into this
possibility, or would it just seem too far fetched for them to consider at
all? Maybe they are missing the boat here.
Matt Broze
>
>
>Cheers,
>John Winters
>Redwing Designs
>Specialists in Human Powered Watercraft
>http://home.ican.net/~735769/
>
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