Re: [Paddlewise] speed with versus against the current

I may have a fundamental misunderstanding of the original post, but I
will 
comment anyway:

John Winters wrote (in response to Joy):
> 
>snip
> >
> >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.

The V, of course, is velocity of the paddle relative to the water.  So,
if you are paddling with
the same cadence and stroke length, etc. (neglecting for the moment the
effect of
wind speed on your velocity relative to the water), you produce the same
thrust whether you
are paddling upstream or down.  You also move at the same velocity
relative to the water.
Your speed made good (speed over ground) is then the vector sum of your
velocity
relative to the water and the velocity of the water relative to the
ground.

Of course, you do feel your acceleration/deceleration (relative to
ground) when
you enter water that is moving.  Maybe that's the basis for the feeling
that
you're working harder when you're paddling in a contrary current.  It
doesn't
explain the apparent difference in boat performance, however...
> 
> >
> >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.

I have noticed that when paddling with the wind, I "feel" like I'm going
slower.  But
I'm pretty sure it's just because my velocity relative to the wind and
waves is
slower, so it "appears" like I'm going slower.  In hot weather, I think
the additional
cooling one gets when paddling into the wind is significant.  Also,
sometimes when going
with the waves (wind), I have to work harder to keep the boat going
straight.  Especially
if I'm using poor technique.  This is related to wind and waves, and not
directly
to current speed/direction.

My contribution,  

Dave Carlson
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