Hi Andy I've R/C'd two of them in the last 25 years or so. First one had the stock batteries and motor. then I used a mechanical speed controller on a MULE pulse radio to get FWD, Stop, revers, right and left. 'Bout 12 years ago I did another one with modern proportional radio. Changed the batteries over to NiCads, still used a servo driven mechanical speed controller that gave two forward speeds, stop and reverse. The only shortfalls of the as designed drive system are the little rubber hoses that connect the gearbox to the prop shafts. With the first mechanical system that I used the props went from full forward to full aft. Occasionally they have enought pull to pull the prop shaft out of the rubber tube. If I do another I'll hunt for U-joints to make a better connection. 9 volts out of sub C nicads gives a nice realistic speed. It does need some balast inthe hull and in the stern to sit at the scale waterline.

HTH

Tom