You can have a closed cooling system like you have on a car, but instead of the air cooling the water via a radiator, the sea water cools the closed coolant water via an intercooler, if you see what I mean. Thats how my boat is set up, dont know whether it'll be up to the task of cooling 900bhp though.
I've had boats in the past that just used raw sea water pumped straight through the engine with no problems though, so I reckon it'll be fine as it is. Just find out what type of engine it is , probably mercruiser, and ring them and ask.
Edited by - julians on 22 Oct 2004 20:47:10