motor height

[skynard]

hello ,well i got my 81 johnson 60 hp 2 cylinder back together and put her in the water yesterday ,seems to run fine now .one question that i have is where should the center of the hub be compared to the bottom of the boat for proper height ..motor is on a duracraft 15x42 aluminum bass boat ..the only place the motor would not suck air was on the lowest pin setting ..it has 5 pin settings ..is my motor mounted too high ?the center of the hub looks to be about 6 inches below the botoom of the boat ..any help appreciated ..thanks skynard

 

[Dhadley]

Re: motor height

Motor height (X dimension) and trim angle (in and out) depend upon the propeller and set up. Prop blade area, blade style, rake, cupping and diameter are some of the things that determine motor position. You can also factor in weight distribution in the boat(including motor set back, if any) and style of the running surface. <br /><br />The best thing is to try different positions with your existing prop, keep good notes (WOT RPM's, speed and water pressure) and then try other props based on your baseline.<br /><br />Good luck!

 

[ehenry]

Re: motor height

Skynard, What everyone in this forum has told me and what I've read in previous posts is that the cavitation plate needs to be level with the bottom of the boat.

 

[skynard]

Re: motor height

thanks for the help fellows , it looks like the cavitation plate is pretty even to the bottom of the boat ..the prop is new 12 1/4x 15 not sure if it is cupped prop or not ..I just thought the motor may be set to high since i cant raise my pin setting any higher than the bottom pin with out sucking air or what ever it is doing .you know how they do when you set the pin setting too high ..anyways i got my stingray fin from cabala's today so im gonna try it with a higher setting ..thanks alot skynard

 

[skynard]

Re: motor height

thanks DHADLEY I dont really want to try a new prop as mine is a new one and 12 1/4 x 15 seems to be what the book calls for in a boat my size ..just wonerind if they installed the motor right since it did not come out on the boat ..but I think between you and EFHENRY you answered my question .thanks skynard