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Don Burke wrote:
> 
> From: Joe Citelli <joe@po*.co*>
> 
> > How could a fin with less surface area and rigidity possibly generate more
> > thrust in the water than a fin with greater surface area and rigidity?
> 
> If the smaller fin puts less water in the wrong direction, less surface area
> is needed.
> 
> If the flex in a fin causes more water to go straight back, the flex is a
> good thing.
> 
> An extension of your argument is the use of a 4 by 8 sheet of plywood on
> each foot.  Since that doesn't seem to work very well, perhaps the
> hydrodynamic problem is a bit more involved than just surface area and
> rigidity.

I'm sure that someone's going to clobber me for this but:

"For every action there is an equal and positive reaction"

is what I think, or something very like it, someone very famous once said.

If that is the case, and I think it is, then an "easier but more
efficient" fin is an impossibility.

A more slippery car, or diver, is a possibility, has nothing to do
with force/energy/action/reaction.

Folks,

Consider yourselves as engines, which you actually are.

- If you use Force fins you will kick x times to achieve a given
distance (all else being equal) and expend y energy.
- If you use split fins you will kick x times to achieve a given
distance (all else being equal) and expend y energy.
- If you use absolutely the best fins you will kick x times to achieve a
given distance (all else being equal) and expend y energy.

The ENERGY requirement remains the same for a given distance, never
mind the fin (all else being equal). Other things can, and will, vary.

The mere fact that some novice raves about farce (sorry, Force) fins
and their (ease of use) efficiency has everything to do with their
(lack of) energy efficiency. The less energy demanded, the easier to use.

THE POINT?

The energy you expend will, never mind the fin, achieve the same
distance (all else being equal).

I think I'll now take up tiddlywinks and unsub real quick. ;)

Cheers,

Christian


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