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4 Blade or 3 Blade on volvo 270-gctid376062

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    4 Blade or 3 Blade on volvo 270-gctid376062

    My boat is a 1985 bayliner 16 foot with an inboard aq125b (125 horse) and a volvo 270 outdrive. I have a 3 blade 14 x 21 r prop on it and I can't get to its full RPM's. At WOT I get to 4200 RPM and its max RPM is 5000. I am looking at getting a 14x19 prop but am stuck on if I should get a 4 blade or 3 blade. Any help is welcome as well as comments and other suggestions!

    Thanks, David

    #2
    I should also include that I would like to pull skiers and tubers. Top speed isn't my number one priority, planing out is more important. I heard the the 4 blades can wash out while doing sharp turns.

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      #3
      have the rpm's dropped off with the existing prop?

      i.e. did it "used to" reach higher rpm with the 21P

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        #4
        No it didn't. I just got the boat last summer and I started contemplating getting a different prop when it takes for ever to plane out and after reading what RPM's it should be running at at WOT.

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          #5
          i'd say four blade 19 or 17 pitch, get rpms up and get the four blade hole shot for towing and running heavy.

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            #6
            Reel Power wrote:
            i'd say four blade 19 or 17 pitch, get rpms up and get the four blade hole shot for towing and running heavy.
            If I am having issues with the 21 pitch wouldn't a 19 pitch 4 blade be pretty close to the same in terms of how hard the engine would have to work?

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              #7
              azafata26 wrote:
              If I am having issues with the 21 pitch wouldn't a 19 pitch 4 blade be pretty close to the same in terms of how hard the engine would have to work?
              That extra blade acts like 2" of pitch, RPM-wise. My 16' '83 AQ125A ran a 14x19 at 4800 RPMs. If you go 4 blade, you'd probably be looking at a 17" pitch, like Reel Power wrote. JMO

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                #8
                tbear wrote:
                That extra blade acts like 2" of pitch, RPM-wise. My 16' '83 AQ125A ran a 14x19 at 4800 RPMs. If you go 4 blade, you'd probably be looking at a 17" pitch, like Reel Power wrote. JMO
                First tbear I like your profile picture

                Second the only 17 pitch prop that I can find is a 14.5 inch prop....Does this effect it very much seeing that it's only a half inch?

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