Re: Trim Question?
Trim all the way down/in when getting up on plane. Once on plane, pull back throttle when boat settles in and then trim 'er up/out and you'll hear revs build.
At this point... there is no other answer than "just experiment". Get a feel for where she stops building revs but still bites the water with the prop. You could trim up so far that the prop isn't biting, or the hull is so far out of the water that it porpoises (nose goes up/down in rhythm).
For me, cruising trim and full throttle trim are about the same: I get the drive up/out which lifts the hull and saves me fuel and gives me a good return on the throttle by giving me all the RPM for that given throttle setting.
When it's rough seas, I trim down/in more and maintain more bite/control. If I want to cruise on glass flat water, the darn trim is just as high as if I am making a full throttle run. If I have lots of turning to do, the trim comes down/in a bit. See a pattern here? More bite = more control. Control means more stuff (hull/drive/prop) is in the water, so that = more resitance which = more fuel burned.
You have to practice. A big chunk of your learning curve will be to get on plane with the drive down/in. Get on plane, pull throttle back as she starts to run up and then trim 'er up/out until you see she is building revs and stops building revs. Now you have to find the happy point, which is different for all boats and conditions (as well as preferences).