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Thread: Will prop change help on 50hp Mercury

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    Default Will prop change help on 50hp Mercury


    16.5ft Alumacraft Prowler with a 2017 Mercury 50hp. Boat ran 35mph wide open when I first got it but since adding another battery for the Ultrex, Spyder Lok rod holders and transport rack it now maxes out at 31.6 to 32.0. I'm not trying to win any races but it feels really lazy. Current prop is a 11.4 12P 3 blade and max RPM is 5900. If I went to a 11P would the RPM be too high and would it even help the top end MPH? Current prop has a little damage and I feel some vibration just above idle so I want to replace it no matter what. Any suggestions are appreciated.

    Thanks..
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    At 5,900 rpm at wot...I would stay with same size and pitch prop.
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    Quote Originally Posted by "G" View Post
    At 5,900 rpm at wot...I would stay with same size and pitch prop.
    Thank you sir...
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    You are probably just sitting too low in the water, switching to a 4 blade will give you more stern lift.

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    Where is your cavitation plate in relation to the bottom of the boat? Like G said, 5900 is pretty close to right, dropping down a pitch is going to likely put you all over the rev limiter, and reduce your speed even more. You could go up a pitch and possibly gain a little speed, but your hole shot will suffer.
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    Quote Originally Posted by DHC View Post
    Where is your cavitation plate in relation to the bottom of the boat? Like G said, 5900 is pretty close to right, dropping down a pitch is going to likely put you all over the rev limiter, and reduce your speed even more. You could go up a pitch and possibly gain a little speed, but your hole shot will suffer.
    Plate is right at 2.5" below bottom of the boat. I have experimented with a Stingray hydrafoil because it takes a while to plane out. Seems it runs about the same speed with or without.

    Thanks for the responses guys.
    Philippians 4:13 "I can do all things through Christ which strengtheneth me"


    Wear that PFD, the life you save might be your own!!

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    Quote Originally Posted by need2befishin View Post
    Plate is right at 2.5" below bottom of the boat. I have experimented with a Stingray hydrafoil because it takes a while to plane out. Seems it runs about the same speed with or without.

    Thanks for the responses guys.
    The anti-cavitation plate should be even with or just above the bottom of the boat. Google it and see what I am talking about.
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    Quote Originally Posted by Barnacle Bill View Post
    The anti-cavitation plate should be even with or just above the bottom of the boat. Google it and see what I am talking about.
    What he said
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    Well, the motor is mounted as low as it can go. I have several holes I can use to move it up on the transom. Looks like all the control cables and wires have plenty of slack to support a move upward. Shouldn't be that hard to move it. Any idea what this engine would weigh?

    Thanks again for the info guys..

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    Philippians 4:13 "I can do all things through Christ which strengtheneth me"


    Wear that PFD, the life you save might be your own!!

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    320lb plus oil and prop. Alumacrafts like the motor high, id go 2nd from the top.
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