Need help finding the right size prop

Discussion in 'Inboards' started by naturalmystic, Sep 8, 2007.

  1. naturalmystic
    Joined: Sep 2007
    Posts: 1
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    Location: Tahoe

    naturalmystic New Member

    My boat is a 19ft. 1973 Century Arabian V-drive with a Crysler 440 with 330 hp. I will be using it at 6500 ft elevation. Does anyone know what size prop I should be using? With the prop I have now is a 13d-13p and the boat is running with really high rpms (5000 or so) and not really planing out very fast. I would like to use it for water skiing. Thanks
     
  2. Jango
    Joined: Aug 2005
    Posts: 519
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    Location: Mid Atlantic

    Jango Senior Enthusiast

    What RPM do you want to run at? Weight of Boat with half tank of fuel and Driver? Also V-Drive Ratio - 1:1 ?
     
  3. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    Hi naturalmystic,
    Without knowing the hull configuration, weight, torque curve, etc it's hard to specify an ideal prop from scratch.
    But you can look at it from the perspective of "here's what I have, I want to change it a little bit from that and see if that's better". Looking at it this way: You have a 13x13 prop, you're revving a bit high, and you want better low-end bite for fast planing and water-skiing pull. That implies you need more thrust at the lower RPMs, and you can swing a slightly bigger prop at the top end. If low-end performance were OK in the present state I'd suggest going up an inch in pitch, but since you want better low-end bite, I'd suggest you add that inch to the diameter instead. Try asking your prop shop what they think of testing a 14x13 on it, if you have the clearance for a prop that size to not hit the hull.
    Another factor - what style of blades is the current prop swinging? Sometimes a different blade shape can change the way the boat behaves.
     
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