Re: [Paddlewise] speed with versus against the current

Joy wrote;

(SNIP)
>
>I'm not sure about this.  When you say "the sensation of greater work" do
>you mean that you feel like you're working harder, or that you feel like
>you're working more efficiently (i.e. more results for same level of
>effort)?  I definitely find that it feels easier to paddle into a
>light-moderate headwind and seas than to paddle with a light-moderate
>tailwind and following seas - same as what Jerry was saying.

Whenever one changes pace from natural pace to a new slower or faster pace
the sensation of work increases even if effective work remains constant.

>
>You said that when going upstream:
>
>> the force on your paddle will
>> be less because the paddle speed through the water is lower
>
>Now I never took physics past high school, and I'm not mechanical, but
>won't the force on your paddle be the combination of your force against
>the water and the water's force against your paddle?  So the paddle speed
>is lower because there is opposing force from the water, but in fact the
>combined forces should be the same, no?

The force on the paddle is F = CdAv^2

If velocity through the water is reduced the force is reduced. When you are
paddling upstream the water has a velocity in the same direction as your
paddle.  In context, to maintain the same thrust while paddling upstream
one must paddle at a faster blade velocity relative to the paddler (and
boat). To develop the same thrust as you would in still water the blade
velocity through the water must be the same.

>
>I've never timed myself going upstream and downstream over the same
>distance in the same conditions.  However, I think one of my paddling
>buddies said he did, and it wasn't an illusion of speed - he actually went
>upstream/upwind faster than downstream downwind.  (Greg, have I got that
>right?)

Not very likely.

>
>Earlier this week, before reading this stream, I found just the same
>thing - out on a lake in a borrowed K-light, going downwind with small
>following swells was no fun and the boat didn't handle well and
>definitely moved slowly.  I thought I was just tired, but when I turned
>to go home I positively flew, and it was a blast!  I really wish I had
>timed it.

Here you are adding an additional factor -  a boat that handles poorly. If
it were a better handling boat your downwind speed would have been much
better than your upwind speed. You might even get the boat to surf if the
waves were large enough. It is possible that some boats handle so poorly
downwind that they might actually be slower but that is never the case with
a well designed boat. Anyone with such a poor boat should seriously
consider selling it to some poor unsuspecting chump that you don't much
like.

Do not confuse the performance of one boat with the performance of all
boats.

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



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