Proper Motor Height

[jrampey]

I have just purchased a 84 Champion 19' bassboat w/ 150 Mercury... Got a good deal - it floats and it runs. 3 weeks ago I got it out on the lake for the first real play time. Top speed with 4 adults was 45 - 47 mph @ 5100 rpm. Since then I have read many posts on motor height... <br />Transom height is approx. 23", motor shaft length is 20", motor is mounted 2 1/2" above transom, and ventilation plate is about 4 inches above keel. Prop is 14.5 X 24P turbo?<br />I plan to use this boat as fish & ski - maybe a little more skiing. Current hole shot is not too bad - but I have to work on trim from dead start to top end. To get best speed has 4 - 6' roostertail. Has some right steering torque at any speed above plane.<br /><br />Is 4" above keel excessive? Should I try lowering the motor... I can only get 2.5" lower without drastic measures. Anything that I can do to improve holeshot without sacrificing much topend and simplify trim adjustment would be appreciated.<br /><br />Is 45 - 47 mph all that I can expect - will lowering the unit reduce the topend much? Or should I just enjoy it as is?

 

[Dhadley]

Re: Proper Motor Height

Welcome!!<br /><br />The correct X dimension (height) for a given motor on a given hull depends a lot on that hull design and the prop design. <br /><br />The Turbo is a very good prop. It sounds like your top rpm without extra people may be near 5500. Probably pretty good.<br /><br />As far as improving the holeshot, you might try enlarging the vent holes. usually starting with the trim all the way in is best but sometimes with a 4 blade you can start with some positive trim.<br /><br />If youre throwing a tail that high (using lots of positive trim) I would guess you can go up with the motor and I'd expect some steering torque.