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Member
Posts: 73
Location: NW Illinois | Actually, I have a couple questions. Just purchased a 19 1/2' Starcraft boat with 150 Merc. The prop that came with it is a 24 degree pitch Aluminum prop, and I am having trouble with it cavitating while playing with trim to optimize performance. Once it starts to cavitate, I have to back well off of throttle or quickly tilt down considerably to stop it. RPM's at full throttle without cavitating are 5100, and speed is not what it should be.
I have two other props for an older Merc 150, both 20 degree props. First, would props for a 1984 and 2000 Merc be interchangeable, and if so would a 20 pitch be better for speed and less cavitation, or worse? How does pitch effect performance? I have one stainless "Hooter" prop and one aluminum prop that, assuming they are interchangeable, could be used. I have never used anything but stainless props much, but I know stainless should give me more top end.
Can anyone shed some light on this dillema for me?
Thanks,
John
Troy, I was the "guest" who posted this question without logging in. Could you delete that post for me? |
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| ROOSTER......there are a couple things to remember,when selecting a prop.First is the average weight of the boat,loaded under normal operating conditions,second is the overall performance you are looking to get.The engine RPM's are where they should be,and it may be you are trimming the engine too high,too fast. You may want to trim up slower,and let the boat come up higher in the water,before going for the top-end speed.Pitch works like this...a 24" will move forward 24 inches per revolution,and a 20" will move forward 20 inches per revolution.The smaller the pitch,the better hole shot,and the greater the pitch the higher top-end speed,you will receive.You have to be carefull,because you can over-due the pitching,causing a negative effect,on performance,at both ends of the RPM range.Mercury has a link http://www.mercurymarine.com/prop_selector that may be of some help to you......hafe |
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Member
Posts: 73
Location: NW Illinois | Thanks hafe, just what I was wanting to know as far as pitch. I will definetly check out the web site. Great info!
John |
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