Motor mounting Question

[2sunaz]

I recently acquired a 9' inflatable and a Yamaha 4hp 4 cycle motor. The motor is a long shaft.
My question is; In reference to the bottom of the boat, how low should the prop be in the water for optimum performance?

 

[j442w30]

Re: Motor mounting Question

The anti-ventilation plate (horizontal plate just above the propeller) should be even with the bottom of the boat or 1-2 inches higher. This is something that takes some experimenting to find out which setting works best. Whats the length (from top to bottom) of the transom on your boat?

 

[2sunaz]

Re: Motor mounting Question

My transom is 16" and the motor measures 21" from the top of the mount to the anti-ventilation plate. Hmmm....

It seemed to work well out in the swells and along the coast, but I kept thinking the prop was too low in the water. I have it trimmed all the way in. The GPS speeds ranged from 5mph-7mph which is about what I expected with full load and two people. But I'm really wanting to see what happens if I can raise the motor 5 inches.......

Thanks for the quick reply, you made me run outside and measure everything!

By Gosh!

 

[2sunaz]

Re: Motor mounting Question

San Carlos, Mex

 

[2sunaz]

Re: Motor mounting Question

I should've done a search.....

new guy.