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Re prop. 3 or 4 blade.

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  • Re prop. 3 or 4 blade.

    This is my 1st boat so I have book knowledge of selecting a prop. I have a 19ft 89 Capri with force 125. I bought it with a 13.5x15, but factory it came with a 13x19. Wot rpm is 5800 so I can lose some rpm. I will mostly be cruising to my fishing holes and pulling tubes occasionally. Would a 13x17 cupped 4 blade or a 13x19 cupped 3 blade fit my needs better?
    89 Force 125, 19ft Bayliner Capri

  • #2
    I should add, the boat is 1700lbs, average 3 adults, current GPS speed is 30mph, michigan wheel aluminum prop 13x15 was borrowed and used to get my current numbers. 13.5x15 that was on it was junk.
    89 Force 125, 19ft Bayliner Capri

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    • #3
      If motor is running at near its max wot rpm range factory stated that current prop is excellent. If going per a 4 blade prop, no one will guarantee a spot on performance. Only checkable on a wot run on calm flat water cond as loaded and extra money spent...

      Happy Boating


      Sea Rider 320, 380 Sibs, 450 Rib, 2 Strokes Tohatsu 5,18 & 30 HP Proud Smokers

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      • #4
        The trustworthy rule of thumb is 200 rpm change at WOT for each 1" of prop pitch change. Pitching up will drop your WOT rpm, may increase your top mph, but it will also drag down your hole shot, and could make lower rpm cruising/planing a struggle. It would be great if you could find a 17"P to borrow and assess. I wouldn't go higher if you pull tubes/etc.
        '96 Larson 174 SEI BR. 4.3LX 4 bbl Weber s/n 0F786604. Alpha One Gen II s/n 0F709315

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        • #5
          Wot should run 5000. 5500 max and not continuous. If been told 4 blad props will get you on plane faster and at lower speed, is this true?
          89 Force 125, 19ft Bayliner Capri

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          • #6
            Hi
            just off the cuff, your wot speed is fairly low at 30mph, if all else is good and trimmed well. All being healthy and with that boat and motor you should be seeing 40mph anyway with a good and well pitched prop. Are you trimmed well and how’s the prop condition now ?

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            • #7
              Originally posted by Jiggin4Perch View Post
              Wot should run 5000. 5500 max and not continuous. If been told 4 blad props will get you on plane faster and at lower speed, is this true?
              Depends on the boat.

              I went from a 4 blade to 3 blade and improve both my hole shot and top end.
              ....

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              • #8
                QBhoy the prop is a new michigan wheel aluminum 13x15. The rpms run high and I agree that the speed is not right. I think the 13x15 is not what I need when it's just two adults. It spins too fast for the light load. The problem is in Baker City OR I am 1.5 hours away from a dealer of any kind and a marina is not within 600 miles. There will be not opportunity to test a prop besides the one I have.
                89 Force 125, 19ft Bayliner Capri

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                • #9
                  I’d have thought you’d see a 19” on that to be honest.

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                  • #10
                    QBhoy 13x19 is what bayliner said was original equipment. I'm debating between a 13x19 cupped and a 13x17 cupped 4 blade. Those are the biggest props I would take a gamble on. Prop co also makes a 13 1/4x 17 cupped I could just shoot in the middle to play it safe. Just trying to get some thoughts from more experienced boaters.
                    89 Force 125, 19ft Bayliner Capri

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                    • #11
                      Hi. Wouldn’t worry too much about cupped. Most props are cupped to be fair. You maybe getting hung up on the concept ?
                      15 defo too low a pitch though. You just be screaming with that low a pitch.

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                      • #12
                        Maybe I am because the two I have tested are not cupped. I figured it might be a distinction to be made.
                        89 Force 125, 19ft Bayliner Capri

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                        • #13
                          When you say the boat is 1700lb, is that the weight from the manufacturer? Add 300 lbs for the motor, 30 lbs for a battery, Gas weighs about 6 lbs/gallon, average 175lb/person, a couple hundred lbs for odds and ends, That boat is getting heavy. If the floatation foam is saturated, that can add a few hundred lbs too. Is the hull Hook free? Are you trimming the engine properly?

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                          • #14
                            Assuming this is the boat, you're probably over reving with a 15P prop at wot. I'd say a 17P would be a good all around choice if pulling tubers. A 19P for normal use
                            http://boatspecs.iboats.com/Bayliner...989/bp/66b7331

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                            • #15
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                              With a 15:26 gear ratio, a 15 sounds about right. Is your tachometer accurate? If so ,then a 17 would be a good choice

                              FYI
                              https://www.scribd.com/doc/97366439/...-Owners-Manual

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