Given the size of your motors, props, boat and battery, I would try to find out what the maximum continuous amp draw is foreward and reverse and then pick the one that protects me the most between the battery, ESC and motor. As I told you in an earlier Email, I opted for the waterproof 100Amp forward continuous current with 60Amp reverse continuous current since it will have one ESC for each of my three Graupner Speed 600 BB motors with gear boxes. That may be overkill, but I have a lot of money tied up in my boat and don't want to fry it since I built it and don't want to piss off the wife. I am running 12v10Ah NmH of 10 D Cells each for each motor. We figure that we should get about an hour run time with the 35mm Left handed props from robesch that we have purchased.