Welcome Guest - Sign Up today
Welcome Guest - Sign Up today



Help Tip: If you have a question that has not been answered to your satisfaction in the archives, it is always best to start a new thread of your own. By starting your own thread, you will receive the maximum number of views by forum members.

Please note this topic has been inactive for 90 days. For the best results, please start a new topic.

Thank you all in advance for doing your part in helping iboats run a smooth ship.

Additional forum rules linked below.
See more
See less

3 Blade vs 4 blade props

  • Filter
  • Time
  • Show
Clear All
new posts

  • 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
          Sign up today
          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