On 1-Sep-2005, Mr. C wrote:

It would
show how closely the maximum hull speed formula in Brians link applies
to kayaks. Does anybody know if this has ever been done?

We know it doesn't apply strongly and it is not worth worrying about. First
of all, there's no such "maximum" speed. The hull speed given by Froude's
speed-length ratio of 1.34 is an somewhat arbitrary value that links the
waterline length to the wavelength of the bow wave. Unfortunately, a lot of
folks have interpreted it as a speed limit of some sort.

The page Brian linked to discusses the speed-length ratio in terms of sailboats.
In the case of a displacement sailboat, most designers know that you can't
realistically increase the speed over the so-called hull speed, so the design
of the sail rig is based on that. If you could carry a _lot_ more sail, you
could start pushing past the hull speed. However, that sail rig would cost a
lot (if a significant speed increase is wanted) and it would be a bitch to
handle in most conditions. Since the average sailor never sees his craft
exceed the hull speed with a typical sail rig, the speed-length rule of
thumb starts to look like an absolute law and it enters into the sailors'
legends.

Multihulls and other displacement craft show that the speed-length ratio is
not so much of a limit. Olympic class kayaks do it routinely:
http://www.kayakforum.com/cgi-sys/cgiwrap/guille/wiki.pl?Hull_Speed

The way to interpret the speed-length ratio or the hull speed is to
recognize that it represents a speed that takes a lot of work to achieve.
If you want to paddle fast all the time, then a longer waterline length
is one thing to look for. However, it isn't an absolute guide to the
behavior of a kayak. For example, based on the analyses of a bunch
of kayaks reviewed in Sea Kayak magazine, you can see the following

http://www.greatlakeskayaker.ca/loaVSlwl.htm

You can see that the resistance generally goes down with waterline length,
but there are some exceptions.

Mike