prop selection

[hawgslayer75]

Hey guys been a while since I've been on here i have a 1971 650 with a lower unit off an 1150 i could only get 8 mph out of it no matter what i did, i did some research and found out the 650 has a gear ratio of 2.3:1 & the 1150 has a gear ratio of 1.7:1 the prop i was using from the 650 was a 12 3/4 x 21 pitch only got 8 mph off it the motor is on a 1972 15' browning tri hull the prop that came off the 1150 was a 13 x 17 the best i could tell by the michigan part # i got about 26 mph with that with 2 guys in the boat i was wondering what prop i should use to get a little more speed out of it mabye 35 mph thanks

 

[Chris1956]

Re: prop selection

Not sure you can get 35MPH, but the obvious choice is to try a 19" pitch prop and see what you get. It may not get any better. The reason you got 8 MPH was that you were very overpropped for that motor/boat. The prop pitch needs to be low enough to allow the motor to get into it's powerband, BEFORE it needs that power for the load on it. For example, On my Merc 1500, I could pull 2 skiiers with a 21" pitch prop. When I put on a 23" pitch prop, I could not get above idle speed when I tried to pull a skiier. She would plane w/o a skiier...

 

[hawgslayer75]

Re: prop selection

Ok i appreciate the feed back chris1956 I'll try that.