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

Where so ever do you guys find the time to come up with this stuff?  I have
difficulty in just finding the time to paddle, much less figure out the physics.

Being new to paddlewise, I must say it is fascinating reading. Let me know if
you can figure out how to make these things fly...

James

Matt Broze wrote:

> > 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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