Trim all the way down and go WOT. Then when cooking start to trim up for
max speed / rpms. If the boat starts porposing or the outdrive cavitates you
went too far so rinse and repeat.

Once you *find* max note the RPM's - if it's over 5000 you could prolly go
up a pitch. If you have aluminum prop @ 23 you should go to a 25 stainless.
If it's a stainless 23, have a prop shop make it a 24.

Remember going up in pitch will hurt your holeshot a bit.

Borrow a GPS for best speed measurements.

-W


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PLEASE NOTE: Email address change from to

"werlax" wrote in message
om...
I was on the lake tonight and doing some RPM testing and something
doesn't seem right. The lake was calm and I've got a 4.3L 190HP
Mercruiser on an 18' bowrider (about 2500lbs). The engine is rated at
4400-4800 RPM. The prop is a 14x23P. The literature states that the
boat should hit about 52MPH. Granted, the gauge on the boat might not
be entirely accurate, but I was only able to get about 45MPH running
pretty close to 5000 RPM. I was trying to modify the trim, but mostly
was running about in the middle (if that means much to anyone) - trim
level. I am going to do some more testing, but my initial thoughts
are that I need to go up one degree? To a 24? Is there something
that I could be doing wrong to get these results?
Thanks for any help!