Proper Motor Height

[Margarita Man]

What is the proper height of the motor in reference to the bottom of the hull? Since there are several holes on the motor mounts I know there is a rule of thumb on this height but I could not find it. How many inches below the lowest point of the hull should the props be?

 

[deejaycee_2000]

Re: Proper Motor Height

the anti-cavitation plate should be in line with the bottom of the hull .......

 

[Dhadley]

Re: Proper Motor Height

The AV plate should be no lower than the bottom of the hull. How high up it goes from there depends on how good of a prop you use and how it reacts to a given hull design.

 

[Margarita Man]

Re: Proper Motor Height

DHadley,
What happens to the performance when you start to increase the motor height? Does the rpm improve or do you get more speed as long as you dont start to cavitate?

 

[Dhadley]

Re: Proper Motor Height

The higher you mount the motor, the less drag you have from the gearcase and therefore it's more efficient. So, yes - the higher you go the better design prop you'll need. But you have to temper that with hull design. On some boats we actually run the propshaft even with the bottom. On other designs you'll get the plate up a couple inches and that'll be about it.

 

[Margarita Man]

Re: Proper Motor Height

Thank you for that advise, I will move my motor up and see which gives me better performance.

 

[deejaycee_2000]

Re: Proper Motor Height

Moving it up too much will cause you motor to just cavitate and not get anywhere ... so you will have to play with it and see on what height you get the best performance ....

 

[bigtwin]

Re: Proper Motor Height

Remember to keep an eye on your water pressure gauge (if you don't have a gauge verify flow from your indicator) mounting your motor too high could cause your water pick-up to draw air.