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Fiberglass vs plastic
On 28-May-2004, (William R. Watt) wrote:
If a paddler is routinely using a kayak under conditions where skin friction
dominates, they'd be better off using a shorter kayak. If they are routinely
pushing against wave-making resistance, they should get a longer kayak.
Sorry it's not an inverse relation.
??? The more you say about small craft hydrodynamics, the more I realize
how little you understand.
Skin friction increases with length, while wave-making resistance decreases
with length. Minimum total resistance is where the sum of the two is minimum.
For a given displacement, this occurs when the two are roughly equal. This
will also yield the optimum length for a given velocity at that displacement.
If you paddle where skin friction dominates, that means the kayak is too long.
If you paddle where wave making resistance dominates, the kayak is too short.
I don't think 10% is out of order in anything less than rough conditions.
You're still talking thru your hat, Willy. Unless you can cough up a valid
reference, I'll go with Brian's numbers.
Brian didn't provide any data.
He said 2% or so.
You can work it out from the data on my
website. I'd be interested in seeing more precise data than what I have. I
could only find generalizations at the time.
You have no such data that I've seen. Where do you have the data that indicates
how much resistance is due to scratches?
You should get out more. Rough conditions are when kayaking gets interesting.
The fact is that kayaks are used in rough conditions (as would be defined by
marine architects) _most_ of the time.
And where do you get that data, in your dreams?
"The Shape of the Canoe" by John Winters.
Mike
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