Thanks Alan.


Colin

The set-up I have just bought for my 34" fire boat should do you, as your boat will be lighter, you might have to try a few different props to get the best results. Plastic ones are cheap
The motor is 1250 rpm and will take 45 amps, it's an outrunner so you will not have to mess with water cooling, it is also cheap, about £13 from Giant Shark

http://www.giantshark.co.uk/product/168468/xyh35-42-1250kv-45a-brushless-outrunnerant
I have one of these XYH motors on my airboat and it goes well even underwater 😑
Couple this with a Hobbywing seaking 90 amp ESC version 2 not the cheapest ESC but I use them in my fast electric boats and they have been good, get a program card to go with it, makes life very easy, this ESC has reverse as well.
You will have to shop around for the best price on this.
You will also have to water cool this ESC.

Alan