Sounds like you need a better ESC. Proboat sells a nice one with 70 amp continuous current forward and 30 amp continuous current reverse. The other responder mentioned EBay. I just bought 10 waterproof ESCs from a seller in Hong Kong for $20.00 each and they have proven to be quite good. They are 100 amp continuous forward and 60 amps continuous current reverse. I have been using them on a PT boat that I just build and have one on each of the speed 600 motors each of which is powered by 10 D cell NmH 12v10aH battery packs. So far I have not discovered any heat build up in the motors, ESC or batteries after running them full out for one hour. You might take a look at the Ebay site. Just remember, however, you will continue to burn up boats if you don't pick wisely so don't be pennywise pound foolish.