Re: [Paddlewise] Your expertise needed again

-----Original Message-----
From: Steve Cramer <cramer_at_coe.uga.edu>
To: Paddlewise <paddlewise_at_lists.intelenet.net>
Date: June 22, 1999 8:16 AM
Subject: Re: [Paddlewise] Your expertise needed again


>
>> Poly does scratch differently from laminated boats by having raised
hairs
>> of material that increase resistance over time more than similar
scratches
>> on laminated boats that do not protrude from the surface.
>>
>The question I was interested in the answer to was do these scratches make
>a detectable difference in the performance? Greg Barton can probably tell
>the difference. A test tank can probably tell the difference. Would be
>expect anyone else to be able to tell the difference between a new poly
>hull and a scratched one?

At the end of a long day it does make a difference but I doubt if many
people can get in a scratched boat a tell it has more resistance without a
smooth boat to compare it with.

I have this little story to support the point. Some years back a person who
owned one of my canoe designs came to me asking if I had redesigned the
boat. He said that a friend had bought a new one and it was faster than his
old model. He said he tried the new boat and there was no question it was
faster.

Now the interesting part. Both boats came from the same mold and weighed
within five pounds of each other. The only difference seemed to be the
badly scratched bottom of the old boat.

So, can you tell the difference? Maybe not. But, on the other hand it
exists and maybe so given the proper circumstances. For the numerically
infatuated I increase the coefficient of friction by 0.001 for poly boats
in KAPER. It seems to fit the test tank data we have.

>
>No question that glass hulls are prettier. Although it's rare to see the
>multicolor effects that Perception and Dagger do in plastic done in glass.

Hmmm, some people would not consider that "better" aesthetically. :-)

As the Devil once said, "Pretty, but is it art?"

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

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