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3 Blade vs 4 blade props

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  • 3 Blade vs 4 blade props

    I have a 350 Mag tournament ski, inboard, ( Sea Ray - Spitfire) and I am considering changing the prop from a 13 pitch 3 blade to a 4 blade. What do I need to consider, regarding pitch, when I go from 3 to 4 blades?

  • #2
    Re: 3 Blade vs 4 blade props

    DETERMINING THE CORRECT PITCH:Adding 1 inch of propeller pitch will reduce wide open throttle rpm by 150 to 200. Subtracting 1 inch of propeller pitch will increase wide open throttle rpm by 150 to 200. If you are upgrading from a three blade to a four blade propeller, remember that a four blade propeller generally uses up to 50 to 100 rpm more than a three blade prop with the same pitch. 4-BLADE PROPELLER FACTS:Plane the boat faster than 3-blade propellers Keep the boat on plane at a lower speed Give improved mid-range speed at the same rpm as a 3-blade propeller Provide quicker acceleration than most 3-blade propellers Run smoother than 3-blade propellers Have better holding power in rough conditions are less likely to ventilate in sharp turns provide better low speed handling


    • #3
      Re: 3 Blade vs 4 blade props

      Better yet-look at Mercury's Stainless Steel High Five 5-blade. My 21ft SeaRay comes out of the hole real nice and smooth.


      • #4
        Re: 3 Blade vs 4 blade props

        Graet advice - does that hold true for inboards(Ski boat) as well?


        • #5
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          Re: 3 Blade vs 4 blade props

          we have a correct craft and it is so compleaty different than and i/o boat because of the center mount engine and hull design thay really go through the water rather than rise up on plane to keep the correct ski wake i would talk to a prop shop that works on ski boats or people in the water ski comunitytommays
          If a dirty bottom slows you down what do think it does to your BOAT

          1970 Cal 29 Sea Fever
          1981 J24 Tangent 2930
          Northport Ny