50 merc on a Gheenoe Super. Prop Help needed?

Discussion in 'Prop Shop' started by Captain_Shane, Mar 12, 2011.

  1. Captain_Shane

    Captain_Shane Well-Known Member

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    I'am changeing out my stock aluminum prop. Need hole shot. Figured a 4 blade SS prop was a good choice. Mercury offers the Trophy Sport 4 blades SS in pitches 15-12. I need to get the right one on the first shot. Any of yall have this motor and prop on a small boat? I do not have a tach and have no plans on installing one. Thanks.
     
  2. Brett

    Brett > PRO STAFF <

    http://www.mercurymarine.com/propellers/prop-selector/#

    I tried this selector and it produced the same pitch and diameter
    that I figured out by trial and error on the water.
    You do need to know hull and engine weight
    and typical hull load weight to input.
    I chose the inshore fishing option to start.
     

  3. Captain_Shane

    Captain_Shane Well-Known Member

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    Brett
    I had used that initially to get in the ballpark but a couple hundred pounds gives me a 14P and couple hundred pounds less puts me at a 12P. Would like to be able to jack it up a few inches as well with the 4 blade. Such a touchy calculator!
     
  4. Brett

    Brett > PRO STAFF <

    Using the super 16 hull weight of 350 lbs, outboard weight of 200
    650 lbs of load and 6 gallons of fuel produces a 14 or 15 pitch 4 blade

    If I exceed the capacity plate numbers for the super 16 and use 850 lbs
    then it drops the pitch to 12 or 13 for the 4 blade.
    I'd go with a 14 if I usually fished with the lighter load
    and use the 13 if I usually fished with the heavy load.
    As you know, the only way to be sure is to test with a tachometer.
     
  5. Captain_Shane

    Captain_Shane Well-Known Member

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    Brett I appreciate you taking time to help.
     
  6. TheBrazilNut

    TheBrazilNut Guest


    I thought your boat sunk! ;D
     
  7. mark_gardner

    mark_gardner I Love microskiff.com!

    just get a tach for testing purposes only then once you have it dialed in remove said tacky-meter :D thats what i did, been on the shelf ever since :)
     
  8. aflatsnut

    aflatsnut I Love microskiff.com!

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    Years ago Harley Gheen had a 50 on a classic, I believe. You might call the shop and talk to him, he's retired but goes to the shop most every day.

    Bob
     
  9. Captain_Shane

    Captain_Shane Well-Known Member

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    Went with a Michigan Wheel, SS, 3 blade, 12" pitch prop. Gained top end speed, mid range power, hole shot and keeps on plane at lower RPMs. Could not be happier. Bought it at Frank and Johnnies in Ft. Lauderdale for under $230.
     
  10. TomFL

    TomFL Well-Known Member

    After reading that you must have been pretty far off with the original prop! Glad to hear you got that thing running better, usually with a prop you have to give something up to gain something.

    And for $230 it's a steal!

    -T