Prop guidance/advice please

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  • Prop guidance/advice please

    Hi all... I was referred here from someone at another group. I have a slight dilemma. This past Saturday my prop fell off and down into the lake.. coincidentally right after I installed a jack plate. The motor is a 1987 25hp Mercury that I picked up about a 18 months ago.

    My dilemma is getting a new prop. I never looked at the prop to take notice of what was on there. My research shows that stock prop is a 10 3/8 x 13. The guy I purchased the motor from did purchase the lost prop but doesn't remember what size he bought... thinks it was a smaller pitch tho.

    The boat was running pretty good with whatever was on there until it fell off. lol I was playing with the trim and trying to zero in. I had one more trim hole outward to try when it fell off. And.. my next purchase was a tach to see where the rmps stood at wot.

    The last run before prop took a dive... the boat got up to 25.1 mph according to my Lowrance. Before the jack plate the boat would reach anywhere between 23.5 and 24.5 with 2 people, couple of backpacks of fishing gear, and a small cooler with a 12 pack.

    I will include a couple pics of the boat.. 14' V that I modified by adding the front deck, dashboard and extended back bench using 3/4" plywood. Added trolling motor, stereo, two batteries and two bank charger... all up front. So.. it is a little front heavy and doesn't get significant rise when taking off.. but does run nose up.

    I will also include a the only picture I have of prop with what looks like the model # but I cannot make it out.

    My question is... what do I do? Get the stock prop and hope for the best? I'm not concerned with hole shot really... just want max efficiency and max speed for this boat and motor combo.

    Suggestions welcome and thanks in advance! If you need more info... let me know and I will do my best!

  • #2
    It has been suggested in another group... based on the info provided... that I go with a 10 3/8 x 11

    Does this sound about right?


    • #3
      I would think a 12 pitch prop would work well if your shooting for 5500 RPM at 25 MPH.
      but it would appear the Quicksilver QA2106R is the only one they even offer anymore. its 10.3/8 x 13
      so if your going aluminum, that is your only choice.

      Ken Reeves
      [email protected]


      • #4
        Hi Ken... thanks for getting back to me. Like I said above... What I'm shooting for maximum efficiency and whatever speed comes with that efficiency. I do not know the math or how to calculate what prop will be needed (based on the physical make up and/or weight of the boat?) or where the sweet spot would be.

        This is his quote from the other page...

        Your motor (a very good one, by the way) uses a 2.25:1 gear ratio and has a 6000 RPM redline, one of the few two strokes that does.
        Last edited by tsgarvey; 07-28-2020, 02:33 PM.


        • #5
          Ken... Like I said.. I do not understand this prop stuff.. but trying to. Are the following not other options for me to choose from or do they not fit my motor?


          • #6
            get that 12 pitch one
            11 I think you'd over rev it too quick. (over 6000)

            Ken Reeves
            [email protected]