Michael wrote:
Hi,

I'm building a model submarine it will have a displacement of around 500kg
and a length of 4m.
Having worked out a rough idea as to the size of the motor required, 3hp.
I'm now looking for suggestions. Sites like technobots don't stock ones
large enough and so I'm struggling to find an answer.
Then there is the matter of how to control the speed. Ideally I'd like
proportional control.

So, does anyone know where I can find a large enough motor, ideally with the
electronics to control it? The onboard power will be provided for by two 12V
batteries,
of which the AH is still undecided.

Thanks

Michael

Too easy.
Go get yourself an underwater scooter, and re work it for your needs.
Already watertight & speed controlled, with the right propeller.
The kind a scuba diver holds in his hands.
Like this
http://www.scuba.com/shop/product.as...&utm_campaign=

On Sat, 05 Nov 2005 17:13:13 -0500, Glenn Ashmore wrote:

I doubt you will find a 12VDC motor over 1HP. www.surpluscCenter.com has
2HP 24VDC motors that draw 72 amps ad full load for $200. You might also
look at old automotive starter motors. Not sure of the HP but they are very
popular for barstool racing in the 12V classes.

Every car that has a starter motor in it has a 12 volt motor that has a
rating way higher than a simgle horsepower......

Most car starters pull way over 100 amps when cranking the engine....
Assuming your starter draws 100 amps at 12 volts = 1200 watts.

The last time I checked the horsepower was supposed to be something like
762 Watts....


I rest my case.


Mind you they arn't rated for long term running... tending to overheat
rather quickly!

Pip