27' H&H Wheel Size

Discussion in 'Downeast Engine Room' started by PatrickPresti, Jul 12, 2018.

  1. PatrickPresti

    PatrickPresti Senior Member

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    Hi Guys,

    I have a 27' H&H with a 350 Mercruiser Horizon and a ZF 2.5:1 turning a 21"x17" 4 blade propeller. I had it at WOT today and it was turning 5500+ RPM's.

    Does anyone know if this is the correct propeller size?

    I need to hand tach the the engine and gear to start eliminating stuff.

    Any help would be greatly appreciated!

    Pat
     
  2. BillD

    BillD Captain

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    Kittery Maine boat ?

    If so, very very nice 27 H&H
     
  3. Captinlon

    Captinlon Member

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    check your engine spec but I think your right on the money. if I remember right my merc horizon only turned 5500 rpm
     
  4. PatrickPresti

    PatrickPresti Senior Member

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    I thought it was between 4800-5000 RPM's....
     
  5. PatrickPresti

    PatrickPresti Senior Member

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    Thanks. Yes it is but it seems awfully slow to me. I thought it would have been faster with the 5.7 MPI. I'm concerned with it turning up to 5500-5600 RPM's...
     
  6. xbskt

    xbskt Captain

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    Depending on specs. If you are over spinning but happy with performance then you are under propped and your engine says Thank you. Unless you plan on 5500 all the time. Then not so much...
    What speed was WOT?
     
  7. PatrickPresti

    PatrickPresti Senior Member

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    I just ran it real quick yesterday. I didn't look at the speed when I was turning 5500-5600 RPM. I am going to photo tach it over the weekend to eliminate any tach or transmission issues. I will post once I get more information...
     
  8. PatrickPresti

    PatrickPresti Senior Member

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    I was hoping to get a 17 knot cruise but I don't know if that's possible?
     
  9. BillD

    BillD Captain

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    I sea trialed the boat before you purchased it. I recall the owner saying he cruised @ 4400 rpm.
    I think 18 knots was the number...boat moved right along for a 300 hp Merc. The "350" designation could be the torque...not sure.
    I was assessing the 27 H&H for maybe an engine upgrade to a 480 QSB 5.9 2:1 gear...22 knot easy cruise.
    Very very nice boat !
     
  10. PatrickPresti

    PatrickPresti Senior Member

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    The "350" is the Cubic Inches of the engine. It's a 300 horsepower engine. I don't need to cruise at 22 knots. I'm okay with 17 knots. I will get better numbers over the weekend...
     
  11. eyecatcher

    eyecatcher Senior Member

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    it should be 4600 -5000 RPM probably could go with two inch more of pitch if everything else checks out
     

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