Re: Can i trim too high at WOT?
Water intakes are setup (on Mercs anyway) to pick up water at high trim angles. Where you get into trouble is with a jack plate whereby you raise the engine to the point where you start to expose the inlet holes. What the guys do then (per Walleyehed) is to just plug the upper couple of holes and continue doing what they were doing.
As the other guys said, before you do that, with a normal transom mount, the prop will start coming out of the water causing an increase in rpms and loss in mph. I had a 17' ranger with a 115 Merc and I'd trim out to get my max mph while watching both gauges. When what I said started to happen I would just tuck her in a tad till things went back to normal.
Besides, you have an OT alarm that will sound if your block internal temp gets to about 195F.
HTH,
Mark