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prop size

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  • prop size

    I currently am getting only 5000 RPM with a light load, trimmed up, and at WOT. I have a two 19 pitch props now, but I am not sure what size they are. (The prop says 19 M on the hub) Would the diameter be written on the inside of the hub? I am looking to resize props to get around 5500 rpms maxed out and I am thinking and have been told to keep the 19 pitch and get a 1/4" smaller prop. Any thoughts on this? At 5000 rpms the max speed is around 47 mph.

    I need to find out what size props I have in order to go smaller if that is the most logical explanation. I could go to a 17 pitch also I suppose.....this is my first time with re-propping, hence the reason for the somewhat basic questions.
    1984 MAKO 254[br]Hartsville, SC

  • #2
    Before you make any decission. The prop you have need's to be checked. Pull it off and take it by a local prop shop. They will stick their Pitch block's on it and then you will know what you have. Then the decission to get another prop can be made acuratly and not just guessing. Guessing cost's money.

    The number's may very well be stamped on the prop you have, but whose to say that prop hasn't been reworked and no new number's stamped on it.

    perhap's the same prop shop will work with you to try several diffrent prop's too.


    • #3
      Your speed sounds great, GPS?

      Another item to check is your tach calibration, if it is off only a couple of hundred rpm, you could already be dialed in, and not need to re-prop. Tachs can vary, price, quality, analog & digital etc.


      Our 88 231, last week: Yamaha 225 Excel, 1/2 fuel (80 gallons), 3 persons onboard, light chop, 5400 rpm max, (digital yamaha tach), 40 mph on gps, running two opposite courses. We recently had the prop rebushed and straightened, so we are going to leave it alone, happy to get what we have!

      1988 Mako 231[br]Jackson, MS


      • #4
        That '19m' it black? Most likely the painted stock Yam s/s wheel...they suck. Look at the blades, almost cleaver like.

        I replaced my stock yam 19p wheels with 17p stillettos...they are so much more the RPMs I wanted, but didnt lose speed ANYWHERE...actually gained on the top end. And I have alot more trim response to boot as trim comes from the bladed tips, which those 'm' props have none of

        As far as the rcommendation to remain at 19p and change diameter..IMO whoever told you that is way off. Lose pitch, a small change in diameter isnt going to do much
        1990 261 T/2001 200 HPDIs[br]Basking Ridge/Mantoloking NJ[br]


        • #5
          My reading is from the GPS. The props are stainless.....whether they are the original props, that I don't know. And the tachs are Yamaha digital gauges. I don't know of any prop shops near here....I am 2 hrs from the beach, but I will try to do a little digging and see what I can come up with.
          1984 MAKO 254[br]Hartsville, SC


          • #6
            Pull the prop and look at the hub. The size is located there.

            Capt Kevin ~~~><((((*>[br][br] 2520 MVSC \"Chesapeake Edition\"[br]Annapolis, Maryland[br]


            • #7
              10-4.......thanks kevin
              1984 MAKO 254[br]Hartsville, SC