Originally Posted by lightning
Would you hold the engine at WOT for long periods anyway?
My boat will do 19mph at WOT (5500rpm with my setup) However it is less noisy and generally feels better backed off a bit to about 5000 rpm (after using full throttle to get up to speed if required) which still gives 17mph, the difference in speed being hardly noticeable.
+1 Same here, 3.4m with 9.8 Twat does 17.5 kts flat out at 5540 rpm. I usually run at 15 or so.
Not sure if Loco's working in US gallons but its often quoted in the UK as 10% of HP at WOT in gallons per hour so 4.5 litres per hour for the Twat which seems to tally with users figures.
Your Mariner at double that sounds none too healthy...