Hookay I'm on a roll.
Look up "boats" on the Sharper Image website
The kit includes a 4 AA cell charger unit, Two transmitters (9V) and two tiny speedsters with sealed NiCad inside hull that can be charged from the charger (2-3 minutes charging to get > 10 minutes run time.)
The speedsters run off two motor pods that are cellphone vibrator motors I think. The props are the size of Revell's PT 109 props. I had been looking unsuccessfully for this size props for as long as the PT boat had been re-issued and I wanted to motorize one. Needless to say the size is ideal for other 1/72 MTB models too and that S-boote. Not only that. The kit includes a pack of 6 spare props, ideal to populate 3 shaft MTBs.
If you cut up a speedster to leave only the guts it is small enough to fit into the Tamiya 1:350 Fletcher. Needless to say the 1:350 capital ships will be dandy for RC conversions.
The Tx has a left and right button pads to switch on each motor. Each button has a top and bottom half, top for Fwd and bottom for Rev. The motor runs only when the button is depressed. So there you have your steering and Fwd/Rev functions.
The mini-speedster motor burps often because of signal weakness or whatever. If the motor can be latched on it can continue running without having to keep pressing a Tx button or worry about it getting out of range (30 feet) . The boat look much better if it continues to run on its own but will be slow enough for you to catch up and regain control should this happen.
Read my post on motorizing the Revell U boat for my ideas on how to improve the RC functions of cheap RC toy units like latching the motor ON. The mini-speedster is a very cheap unit and one cannot expect it to perform like their bigger and more expensive brothers. I don't want to have to buy special hardware installations to put everything (servos, links, speed controllers, etc,) together either. If I can motorize the plastic kits and have some degree of control however imprecise, I'm satisfied.
In MTBs with three props my solution is to use the forward direction wire to feed an OR gate whose output will drive the central prop's motor*. This way so long as either the left or the right motor is on the center prop will continue to rotate Fwd. Should both motors stop or be in Rev the center motor will stop.
*(Salvage a motor from a scrapped cellphone or if Canadian "Princess Auto" has a pack of 10 for CND 9.99.)