Mariner 9.9- 4 stroke has no speed

Discussion in 'Outboards' started by Scott Mckenzie, Apr 4, 2019.

  1. DCockey
    Joined: Oct 2009
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    DCockey Senior Member

    What is the prop? Is it a low pitch prop intended for a "kicker" motor on a larger boat?
     
  2. fallguy
    Joined: Dec 2016
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    fallguy Senior Member

    The prop is okay meaning it is not sheared or spinning out.
     
  3. DCockey
    Joined: Oct 2009
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    Location: Midcoast Maine

    DCockey Senior Member

    The Mercury parts book shows props with pitches from 5 1/2 inches to 9 inches for that engine. Too low a pitch and boat will initially accelerate well but top speed will be limited by maximum engine speed. Too high a pitch and the boat will be sluggish and the engine won't reach top engine speed. 9.9 HP outboards are popular as auxiliary propulsion for sailboats and as auxiliary kickers/trolling motors for larger fishing boats. For those uses a low pitch prop is frequently fitted. If the engine was previously used for auxiliary propulsion the prop may have too low pitch prop for the current boat. Mercury Marine | https://www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog
    Mercury Prop 99-2.JPG Mercury Prop 99-1.JPG
     
  4. fallguy
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    fallguy Senior Member

    Yes. A very fair point. I assumed it worked before.
     
  5. Mr Efficiency
    Joined: Oct 2010
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    Mr Efficiency Senior Member

    More info needed, re loading of boat, I'd reckon one big bozo ( not Scott, of course) in a 14 footer with a 9.9 hp would make it sluggish. I once sat in a 15 footer tin tub with another bloke, neither of us small people, and it would not plane, with a 15 HP motor, that he was using while his 25 was under repair. The 25 easily planed the boat, two up.
     
    fallguy likes this.

  6. fallguy
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    fallguy Senior Member

    ditto
     
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