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=