Hi Alan,
As Malcolm pointed out, ten minutes of full throttle runtime isn't bad at all, considering the size and motorchoice...
To get more speed you'll need twobladed props in the Ø36 mm region, experiment with props of different pitch to see which one gives you the best balance between topspeed and runtime.
More runtime requires a bigger 'tank', aka higher capacity batteries.
Eventually you'll have to deal with the mystery of Lipo's (or LiFePo's) to achieve more runtime and speed without the hull sinking in too deep, which will cost you performance.
When the Lipo hurdle has been taken, another upgrade could be brushless motors.
I say could be, because brushless in a scale boat has it's restrictions; the setup has to be quite overkill, to handle the crawling at partial throttle, as running a brushless setup at partial throttle generates a lot of heat, both in ESC and motor.
Watercooling for both motor and ESC's (one per motor) is mandatory.
A brushless setup is however more efficient than brushed motors which as a rule of thumb can convert up to 30% of the battery power into heat in stead of runtime, brushless setups can reach 90% efficiency.
Regards, Jan.
