A hint that brian_c gave me years ago, and has been used very often in models built by both of us is the use of car electric seat motors (predominently from Ford) that have a 2" (approx) flexi drive that can be fitted to either end of the motor. The "spring" for want of a better word has square ends so you need to make up at least one coupling to fit a round shaft. Absolutely superb....especially when used in a model that weighs over 100lb! Takes the strain of going from full ahead to full astern with aplomb. Biggish motors, but still low drain. BY.
