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

Ralph wrote that this feathered Vs unfeathered paddle business takes on the
odor of religion. I disagree. In this particular case I think he discussion
has an objective of greater understanding of the topic. By raising
objections to each other's points we close in on the crux of a complex
subject and the end product (if we obtain one) may enlighten someone. On
the other hand, if I can find my little wax feathered paddle and some pins
I can put this to rest with out much more discussion. :-)

Matt wrote;

(SNIP)

>This diversion of flow
>around the paddler (that causes the "safe lee" and "hopeless" positions in
>sailboat racing) if it occurs to any significant degree would only mean
that
>the paddlers unfeathered blade would be perpendicular to the flow a little
>later in the stroke.

Perhaps but only depending upon stroke mechanics and then the force would
not act parallel to the line of travel although it might exert a force
against the paddler's arms that might increase his effort. Not sure about
that though. The problem that arises has to do with the turbulent flow
around the boat and paddler. I know of no research on this (I take that
back. I think New Zealanders  some years back worked on sprint boats that
resulted in fairings around the cockpit. Ruled illegal right away though).

I think one has to treat this paddle thing as a system rather than isolated
parts. That makes it complicated and may defy resolution.


>Maximum drag is what I meant by most effected. Not much changes, drag
wise,
>if the flow is withing 25 degrees to perpendicular, so the unfeathered
>paddle would have to be very close to the body to get much benefit from
this
>effect.

I suppose "very close" becomes an issue. For example, I my boat in the
water this afternoon and found the following; During the power phase the
distance from the paddle to my body never exceeded 1'8". Well within the
range where interference effects occur. From exit to power phase the paddle
traveled across the free stream flow and one might even start to suspect
some positive lift occuring. (HMMM?)

As I played about the thought crossed my mind that the paddle might even
serve to reduce net drag. (HMMMM again)


>This may be true in special cases, but my personal experience racing has
>been that when we turn into the wind is when I (in my single) can finally
>catch the double that had been previously out of reach. (Then I use this
>effect--hiding from the wind--behind them and their wake to "draft" them
and
>get a rest before passing). Of course, any angle much off of directly into
>the wind would be a disadvantage to the bigger frontal area of a double
with
>twice the number of paddlers sticking up into the airflow. That could be
the
>reason I caught up or maybe they were all just using unfeathered paddles
>into the wind and I wasn't.

This really surprises me (not the drafting part but being able to catch
doubles directly up wind) . Perhaps these doubles were pretty poor boats or
paddlers or, as you say, you did not paddle directly into the wind but at
an angle. I have never seen any top level single sprint racers who could
beat top level tandem sprints although once one gets down in the standings
four or five places the double paddlers may have slower times than the top
singles. I suspect this comparison has more validity than mixed racing
particularly where the tandems may have poor characteristics.


(SNIPS all over)
>
>If you held the paddle blade directly in front of yourself that would be
>true but it would be hard to paddle much that way (but a near vertical
>stroke might provide a small benefit here).

Maybe this needs clarification. This is, in fact what I do when paddling
strongly. Perhaps before discussing this further we need to define the
stroke under discussion. It sounds like Matt is discussing a stroke that I
would consider inappropriate for use with an untwisted paddle i.e. long
shaft, straight fore and aft stroke, and paddle held at a large angle to
the water. The old racing paddlers used this kind of stroke. The more
modern stroke sweeps across the body and gets held more vertially.  I have
found the "wing" style of stroke superior when one produces high output
regardless of the paddle type (so far). I have some test paddles underway
that i hope will help clarify this.


If we could just get some bored university student to do some wind tunnel
test for us we would enter fat city. Failing that I guess we will have to
muddle along with less sophisticated stuff.

Cheers,
John Winters
Redwing Designs
Specialists in Human Powered Watercraft
http://home.ican.net/~735769/


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