Re: [Paddlewise] Hull speed isn't wave climbing

> So hull speed isn't wave climbing, but attempting to exceed it with a
> displacement hull is.

All of what you say makes perfect sense, except this.  It still remains that
the
force increase is not consistent with grade resistance.  So I would argue
that you're not climbing the wave, you're pushing it at a bad angle - your
cutwater now includes the whole bottom of your hull!

If you had enough horsepower you could climb out of the hole in the water
you made (and reach a higher plane) just like a powerboat does. The increase
in drag from a regime that increases a little less than the second power to
one that increases (during the climbing phase) at near the 4th power is due
to your trying to climb out of the hole you are making in the water against
the force of gravity which is added on top of the drag due to skin friction.
You could adjust the trim drastically to keep your bow down and cutting the
water but this might actually result in even more drag from trying to push
through the water rather than climb over it. I have read that extremely
narrow hulls like those on a narrow catamaran overcome hull speed by slicing
through the wave rather than climbing out of the hole but I don't know if
that is true. The narrow hulls on kayaks and their lightweight do allow them
to go a little faster than the wave speed formula predicts. A wave in deep
water moves at a speed (in knots) that is 1.34 times the sq. root of the
wavelength (in feet).

Matt Broze
http://www.marinerkayaks.com



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