Thanks for the advice. It is indeed a Ribtec 585.
I'll check what size the prop is. Only got it last week, went for a run yesterday. Forgive the newbie ignorance!
4500 seemed about it, altering the pitch didn't seem to make much difference. Sea was pretty calm, and i didn't notice the motor getting sprayed.
I'll take another look tomo. Cheers for the advice.
Russ