Thanks Boys. My model would operate on a faily slow scale speed so the heater motor is an option I shall explore. Now, where's that "Find a part" number !

Used to be very popular with the Tug boat fraternity as they were quite torky and were capable of turning a large propeller. I have one in my Lady Jan Tug. Most were multI poled so they ran very smoothly and worked well on 12v.
If you have the room and the facility to make a suitable coupling, many were 1/4" shaft, then it should work well.
Not as easy to find as EU regulations have stopped the easy access we used to have to scrap yards. Mobile Marine used to stock them but they are heavy so will attract high postage charges unless you can attend a show that might have some.
Dave

I tried to use a 12v 1980 VW camper Heater Motor in a 30" Cabin Cruiser but gave up because the size of Battery / speed was not suitable, possibly would have been OK for a Tug or Coaster.
Good Luck
Chris