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From: Ron and Barb <rbdunningtons1_at_home.com>
subject: [Paddlewise] Length vs Speed
Date: Mon, 14 May 2001 15:58:13 -0500
I try to understand the various attempts to explain the relationship between
speed and length of a boat and, not being into any sort of higher math, fail
miserably. It seems to me that length is only one of many factors that
determine the speed a particular hull can produce. What about hull material,
weight, width, cross section at various points along the boat? To simply state
a longer boat is faster is very misleading. Some long boats are designed to
carry heavy loads, not to go fast.





I would like to see a comparison of, or statistics on, the rate of forward
movement (MPH or FPM) produced by some standard of say, 1 horsepower using 75
Sq. In. of paddle surface, with assumed paddler weights in increments from 120
to 200 lbs., all other factors (wind, current, etc.) being zero. This would
tell me something about what to expect from that boat as far as speed goes.  






It think John Winters mentioned something like this on his site but I can't
find it. Anyone have his current site address?





Regards,





Ron





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From: Michael Daly <michaeldaly_at_home.com>
subject: Re: [Paddlewise] Length vs Speed
Date: Mon, 14 May 2001 21:37:16 -0400
From: "Ron and Barb" <rbdunningtons1_at_home.com>


> It seems to me that length is only one of many factors that
> determine the speed a particular hull can produce. What about hull material,
> weight, width, cross section at various points along the boat? To simply state
> a longer boat is faster is very misleading.  

That's right, so it's important to say "all other things being equal" when comparing
boats of different length.

> I would like to see a comparison of, or statistics on, the rate of forward
> movement (MPH or FPM) produced by some standard of say, 1 horsepower using 75
> Sq. In. of paddle surface, 

That's a small paddle.  The CD Sabella is 84 sq in and that's a small blade.  100-110 would
be more typical.

One horsepower, on the other hand is a massive amount of power.  I seem to remember
reading years ago that Eddy Mercx (the five time Tour de France winner from way back)
could put out one-half horsepower.  Real people can put out much less.  One-tenth of 
a horsepower would probably represent what a reasonably fit paddler could do for a 
long time.  (If you can find it, the Aug '98 Sea Kayaker has an article by Matt Broze on
power versus speed and what kind of paddler it represents).  Kayaks are about the
lowest powered vehicles on the water.

>with assumed paddler weights in increments from 120
> to 200 lbs., all other factors (wind, current, etc.) being zero. This would
> tell me something about what to expect from that boat as far as speed goes.  

The Sea Kayaker reviews give the drag estimates for kayaks in force versus speed
for the kayak plus 250 pound payload.  Using this with the Aug '98 SK will do it
for you.

Mike


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