Is it your position that drag on the hull does not increase with
speed?


JAXAshby wrote:
the induced drag on a hull

A hull doesn't usually have "induced drag." That is a term specific to
the behavior of foils.

... goes up at the cube of speed

wrong

... and has nothing to do
with "climbing the bow wave".

wrong again, at least in practical terms.

Wow, a hull speed discussion with Jax and I almost missed it!




... A cubic function is mathematically well behaved,
meaning nothing untoward happens anywhere on the curve.

Can I quote you on that?



Gene Kearns wrote:
Then it follows from observation of this well behaved curve that,
given sufficient horsepower, a displacement hull is not limited in
speed.

If other factors are not considered, true. But what hull can withstand
the force generated by the nearly infinite horsepower that is required
for marginal increase in speed? Is the hull's reserve bouyancy
sufficient to keep it above the water level of it's own exaggerated wave
train at higher speeds?


Or perhaps, to put it another way, the wave system created by the hull
passing through the water is not limited in speed, either.

Actually, it is. Waves can only travel so fast... this is a physical
property of the fluid that forms the wave.


Thus, given the mathematical example, both the hull and the associated
wave system could travel at, say, 45 MPH for a 25 foot boat ....
assuming adequate available horsepower.

Probably yes.

The difference between "planing" and "displacement" is one of the most
misunderstood things about boats. But very few people can be as
consistently wrong, or as funny, as Jax. He was gifted even as a child.

DSK