The pro boat 30A esc is comepletely waterproof and can be submerged no problem. A three bladed prop is not recommended and will not work according to horizon hobby. If your not feeding the esc too much than it can handle, having a long runtime wont effect the esc with the watercooling. Horizon hobby might send you another one but i doubt that cause you kinda messed up the warranty when you tried using a 3 bladed prop.
ORIGINAL: pompebled
Hi Rich,
If the three bladed prop has the same surface as the stock one, the watercooled(!) ESC should not have burst into flames on 2S (7,4V).
(As a rule of thumb, a threebladed prop draws slightly more current than a two bladed one, but if the stock ESC can't handle that, it was too light for that set-up anyway, 30A isn't much.)
Granted, the 5000mAH gives you a long runtime, but you didn't mention how long the run was before this happened.
The only thing I can come up with is that you ran the boat at half throttle for long periods of time; this heats up both motor and ESC substantually, despite the watercooling.
Partial throttle is not the way to run a speedboat, specially if it's a RTR one where the components selected are on the edge as far as reliability is concerned.
Did you tape the hatch? A few drops inside reaching the ESC may cause the same result.
If none of the above apply I would call Proboat and see what can be done under warranty.
Regards, Jan.