Re: Motor height....need some expert advice
4900 @ 56.3 mph<br /><br />That's probably as good as you're going to get without adding some horsepower, or taking off about 400 pounds of weight.<br /><br />On my hydro, I'm running a stock 150 Merc. with a 26"Cleaver prop, but its only a 500 pound boat with one seat and no gear except the horn and fire extingiusher. The best I've got out of it so far is 77mph at 6000. It has a slip rate of about 2%. But even then, with the 26" prop, I can only get it up that many rpms by going against a slight wind that forces a little more air under the hull to lift a bit more of it out of the water. A 25" prop gets the rpm up a little, but not the speed before I run out of horsepower.<br /><br /><br />If you're always going to run with that much weight-- or a little more even, I'd drop down about 2 inches in pitch.<br /><br />I doubt if you'll gain much speed, but your holeshot will improve and the engine will be running pretty close to its WOT rpm without over-revving, and put you right up around 60mph----<br /><br />which is pretty good. And your prop slipage rate or ineficiency is right around 13% Which also is pretty good for a well loaded fishing boat. <br /><br /><br />Being proped like it is isn't bad, but its sort of like having real tall of a set of tires on a car that doesn't quite have enough horsepower to spin them. <br /><br /><br />All in all, you've done quite well. Getting that engine up out of the water helped a bunch. Water resistance sort of accumulates. The faster you go, the harder and harder it is to push out of the way. However much resitance there is at 20, may be double at 30, and perhaps 4 fold at 40. I've heard that a big fat 'fishing motor' lower unit accounts for more water drag than the hull in most cases. I'd guess raising that engine gave you about 10mph on the top end and cut your prop. slippage rate several %.
