Re: [Paddlewise] random followups

I wrote:
> In looking at watercraft one should consider any parameter
> close to one extreme or the other to be very suspect.

John responded:
>>>>Hmmm. No extremes. Does that mean the kayak business has become the
McDonalds of boat building?<<<<<

Hardly, there is a lot of room for variation in the 95% of the range that
are in the 1st and 2nd percentiles.
Perhaps I should qualify my statement some because there are possible
exceptions. Unless there is one overriding goal that makes all others pale
to insignificance taking any parameter to the extreme (relative to other
boats) is going to leave one with a very specialized craft that if one is
lucky (and/or very good at boat design) will at least do one thing well. At
least in an unconstrained situation. In a constrained situation, one where
there is an artificial rule (such as a length rule in Olympic Flat Water
kayaks--unlike with rowing shells, BTW) then the boat designs for racing
will likely cluster up near what is allowed by the rules (and in their
overall length to waterline length ratio as well). furthermore other things
will be done to the design to try to "beat" the rules. If there were no
rules constraining length, a designer could go to further extremes, well
beyond where any benefit is likely to be derived, and into territory where
there are substantial negatives (even in the one area that is trying to be
maximized). I once calculated that I should be able to paddle a 100' long by
12" wide kayak (one with a potential hull speed of over 13 knots) at the
blinding speed of 1.5 knots. A 100' long kayak is really taking it to
extremes (relative to typical kayaks) but there are single kayaks designed
for unconstrained racing that are up to 23' long (which for even the
strongest humans is probably too long to have any advantage except in the
shortest of sprints). As in most human endeavors the momentum in a positive
direction often overshoots the mark before reality has had a chance to reign
in the exuberance. Just look at the stock market.

For those who want to build THE MEDIAN sea kayak I can report that of 124
single sea kayaks measured for Sea Kayaker magazine the median dimensions
are 17 feet long, 22.6" wide, a waterline length and width of 15' 2" and
21.8", a center of buoyancy of .51, and a prismatic coefficient of .53. (THE
AVERAGE is 16' 9" by 23" and the prismatic coefficient goes to .54)

Due to the popularity of recreational kayaks the average length of all
non-racing non-whitewater kayaks I keep track of has been going down while
the average width has been going up. The average of over 1250 hard-shell
fiberglass and plastic kayaks built in North America is now 14' 6.4" long
and 25.2" wide. Of the 700 or so of the same types of kayaks (that I have
data on) that are built outside North America the average length is 15'
10.2" and average width is 23.2". For nearly 500 wood kayak designs from all
around the world the averages are 16' 1.6" by 23.7".  Taking them all
together (but leaving out skin boats) the average is 15' 2.77" long by
24.34" wide. Is it a coincidence that the kayak that was the best seller in
our store for years was the 15' 1.25" x 24.125" Seda Gypsy? It probably
helped, it did fit a lot of people, but being in the extreme may have helped
it even more (at the extreme low end of the fiberglass kayak price scale).
The fact that we liked it a lot probably helped it as well.

Matt Broze
www.marinerkayaks.com
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