Motor Height -- Prop Size ??

[kirkland]

I have a few things going on right now with my boat It's 17 ft 1989 cajun demon pro not sure how much it ways..I know I should but don't...anyway I have a 1991 70hp rude with a 13 1/4 X 17 aluminum on it, load includes 15 gal gas tank mounted far aft, 3 marine batteries triple bank charger oil tank also mounted far aft as they will go...i'm awaiting a tach(UPS has it) I'm looking for some information about proper height for my motor...currently the center of the prop shaft is 6 1/4 inches below the pad...does this seem like its mounted high????

 

[roscoe]

Re: Motor Height -- Prop Size ??

View the pictire in the link below.<br />The anti ventilation plate (bottom red line) should line up with or be just above the bottom of the hull.<br />That is your starting point.<br />The motor gets raised from that point, depending on handling and performance issues, hull design, jackplate, etc..<br /><br /> http://www.iboats.com/ref/shaft_length.html

 

[kirkland]

Re: Motor Height -- Prop Size ??

Well my anti cavitation plate is a little over one inch above bottom of hull. does then mean it needs to go down?

 

[marinemech1]

Re: Motor Height -- Prop Size ??

runboat and see how it preforms if prop is catching air you may have to lower motor if its not and creating a spray you may have to raise lake test the best way to be sure

 

[moderator1]

Re: Motor Height -- Prop Size ??

If it's Ventilating, we install a more suitable prop....never lower the engine unless you have tested the high-end props and still have ventilation. We can work a prop or buy another, either of which will allow a higher X-dimension

 

[kirkland]

Re: Motor Height -- Prop Size ??

as soon as i get all the stuff back together and have new tach installed i'll be able to provide better information to myself as well to the experts on this board.....<br /><br />what a great site....i would be paying many dollars in maint. and repairs if it weren't for this site...<br /><br />thanks to all that make this site work...including all of us...