RE: Shockwave 26 Brushless.
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.