You could use a wind screen wiper motor and run it off a 6 volt battery. There was one selling on ebay (do a search for "Tug Winch") but I am sure you could buy a new wiper motor for about $20 or a second hand one (at the wreckers) for about $5. Then it is just a matter of wiring it up to a switch which is driven by the receiver to put the motor into forward or reverse. These motors are really strong and would have no problem lifting a boat out of the water, if that is your aim.

Have fun

Greywolf20k