Max RPM and cruising speed question?

[BugEyes]

Hi,<br /><br />My new boat is in the water and it runs fine as far as I can tell.<br /><br />It's a 5.2 meter bowrider with a 90 hp yam from 1999, boat dry weight is about 600 kg apart from the engine and 70 litres of fuel.<br /><br />Max RPM I can get is about 5300 at 34 knots, is that sane values (alone in the boat)?<br /><br />What's a good cruising speed? I have been cruising at 4000 RPM at about 26 knots, is that economic and good for the engine?

 

[deejaycee_2000]

Re: Max RPM and cruising speed question?

i'll say about 3500 rpm is a economical and nice cruise speed, also tilt your engine slightly (not too much) upwards (boat must not bounce) for better fuel economy. 4000 RPMS is fine. I would say running it for an extent period of time at 4700 rpm and up, is not great for your engine, but an engine needs to be run WOT every now and again to clear its throat, but not longer for about 1 - 2 minutes.