How do you make a motor work underwater?

Question

I'm trying to figure out how to make a dc motor work underwater... like in a torpedo and submersibles.. but I can't seem to find anything on how to do it... any help?

Answer 1

You make watertight slippery seals for the shaft to go through and put the motor in an air filled container.   If you were manufacturing it, you could make the case water tight and leave almost no space inside so it would look like a motor running under water - see a trolling motor.

  Certain kinds of motors can be made to run with just sealed wires and the mechanism otherwise exposed to water, but they are induction motors and require alternating current so rotating contacts as used on DC are not needed.

Answer 2

Batteries,and a whole bunch of guidance gizmos some of the old ones used compressed air, Brainy I was going to say submersible well pump,saw a Toy submarine remote control battery operated fellow put it in his aquarium chased the fish around retails for $30 can't recall the brand,right up there with battery airplane   http://www.hobbytron.com/RCSubmarines.ht...

Answer 3

You can use submersible type motors for driving pumps.Cables used are also submersible type. The motors I know are Franklin Electric and they are rated in AC . You can  also use solar pumps which are rated dc.

Answer 4

How about using a sump pump motor?

Sump pumps are already designed to work while submersed in water.