Re: [PSUBS-MAILIST] Wroking on a spreadsheet again

[Charles Samardza <samardza@ezy.net>]

Hi,  there is a formula for what you want, I got it out of a 'Handbook
of Ocean Engineering' that I found in the library.
The formula is   "shaft horsepower) equals "displacement in tons to the
2/3 power" times "speed in knots cubed" times "0.005" times "efficiency
factor"

Displacement can be approximated with "(height x width x length) / 60"
The efficiency factor is a combination of hydrodynamic efficiency,
propeller efficiency, and efficiency of power transfer.

Technically the efficiencies will vary depending on speed, however for
general comparison at max speed, it give a number for comparison.  The
lower the number the better, both the Nautilus and the ww2 German type
21 submarines have an efficiency of about 1.

"Michael B. Holt" wrote:

> I've set one up that has all sorts of designs and their submerged
> speeds and the horsepower requirements.  Some military, some not.
>
> Does anyone want to suggest any relationships I might test, to
> see if I can figure out how to calcualte the required horsepower?
>
> So far, I've divided the speed by the horsepower, the displacement
> by the horsepower ... and probably some other things.
>
> Mike