I'm using air cooled having cooling no issues with the motor @ 26 Amps 264 Watts on the watt meter on a Turnigy 3C 198 grams. Its a 20 inch boat around 700 grams at launch. Like doing FPV getting a ducks eye view . Akaroa harbor
More vids http://www.youtube.com/user/nickatredbox/
P2632 Brushless Outrunner 3800kv
Max current: 32A
No load current: 11.1V/3.2A
Internal resistance: 0.036 ohm
Diameter of shaft: 2.3mm
Its a deep V so it will never be as fast as yours, I have the cheap and cheerful NQS's US$69 for four units. I have tinkered with impellers but am currently running stock.
My ESC is an Turnigy AE-30 with a big heatsink
Currently developing a drop in power module with servo motor jet and ESC as I am building for a friend
The idea being the aluminum which is embedded into hull and in the water will act as a heatsink for the ESC
Happy jet boating I have 2 jet pumps in stock may build a twin hull speed moster with 2 X 4500 KV heli motors ! POWER !