prop size?

Discussion in 'Powerboats' started by maxum, May 21, 2007.

  1. maxum
    Joined: May 2007
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    Location: uk

    maxum Junior Member

    can you tell me the best size prop for my boat?.

    i think im under prop .(is that what you call it) it revs to much and not that fast.

    i just put in a 5.7 350engine new not run yet. so i will like to do this job the same time
    and stop the over rev.i cant tell the size is on it now.drive is alpha one gen 2.

    2300sc maxum,thanks.
     
  2. Jango
    Joined: Aug 2005
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    Location: Mid Atlantic

    Jango Senior Enthusiast

    We need to know:

    1. size of boat - length, width, bottom shape (deepV, flat or somewere inbetween)
    2. Total weight w. one passnger (driver) half tank of fuel.

    3 Brake HP @ what RPM

    4. Final Drive ratio

    Whatever else you can tell us will help.

    Jango
     
  3. maxum
    Joined: May 2007
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    maxum Junior Member

    ok its 24 foot about 2000lbs ,3foot draft, hp260 engine 5.7 vortec q,jet carb
    alpha one gen2 drive.me my wife and my 2 kids
     
  4. maxum
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    maxum Junior Member

    width about 8 foot.
     
  5. Jango
    Joined: Aug 2005
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    Jango Senior Enthusiast

    I believe your total weight of 2000 lb is a least 600-800-lb low. The motor/outdrive alone is more than 900 lb.

    Without more precise details it is difficult to recommend an exact Prop.

    Based on similar applications, I would suggest a 14 or 14 1/2 x 19 P. 3 Blade prop. I believe a 21 pitch will probably not allow adequate max RPM. (4400)
     
  6. Jango
    Joined: Aug 2005
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    Jango Senior Enthusiast

    Just figured prop requirements for a boat similar to yours:

    1. 24' planning hull, 3000# w. Driver only and half tank fuel.

    2. 260BHP mercruiser @4400rpm (5.7L)

    3. 1.5 gear ratio

    Calculated to 15 1/2D. X 17P Full Cup, 3 Blade (.55 D.A.R.) w.10%slip - Max Speed, 44 MPH
     
  7. maxum
    Joined: May 2007
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    maxum Junior Member

    hmm i see.hull spec is good for 50mph.got it out today prop size,4878120a40 19p.?
     

  8. Jango
    Joined: Aug 2005
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    Location: Mid Atlantic

    Jango Senior Enthusiast

    Weight is extremely important in determining Prop size. If boat with Driver only, with minimal fuel was 2400 lb, prop size will be 15 1/2 D x 19 P. Full cup w.10% slip. Max speed 49.2
     
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