Help with Prop Purchase/Selection

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  • Help with Prop Purchase/Selection

    Hi everyone, thank you for reading my post. I will try to be as brief as possible. I just bought a new to me boat. 2017 Glastron GT200. Equipped with a 2017 Mercury 150 Pro XS DFI 2 Stroke ser#2B524737. It came with a new Mercury Spitfire 14D 17P on it after I saw the original no name one was all dinged up and worked a new prop into the deal. The engine manual says it should be stainless due to the high torque of the engine, I also want a spare. Therefore I want to prop it correctly for a steel one. In Canada, no one near me will let me test a prop so I need to be as accurate as possible. I used the Mercury Prop Tool and tried all combinations (top speed, acceleration etc) as well as adjusting for pitch using my Spitfire test numbers (below) as well as using weight (Boat is 1950 w/o engine, 32 Gal, fuel, tried both 300 lbs, me and some gear, and 900 lbs being wife and 4 kids). Across all variations of results the two props that always come up (others change based on configuration) are the Rev 4 and the Enertia BUT with a few variations on D and P for each. My research says, moving from Aluminum to Stainless decreases RPM 1-200, from 4 Blades (spitfire) to 3 Blades (Enertia) Increase RPM 50-100, each 0.1" Increase or decrease in Diameter is +/- 50 RPM, each 1" of Pitch is +/- 150-200 RPM plus load weight, so it is a lot for me to process. The manual says 5250-5750, the tool selects to 5800 RPM. Some sites say prop based on just me, full gas and no load, and others say use you average load, some say trimmed up, others say trimmed all the way down. So I took it out and tested trimmed up and tried it once with just me and full fuel, and once with all six of us. I used the vessleview numbers not the Glastron gauges which are clearly off compared to the vessleview module. Results: (1) Just me, Lake Huron (where our cottage is) almost no wind, and barely a ripple on the water. I hit 5900 RPM 41.5 MPH (rev limiter did not go off which I thought strange as the manual says 5750 WOT limit). (2) Family of 6, full fuel less maybe a gallon, I hit 5300 RPM 34 MPH. I like the control on the four blade, and will likely get a 2 person tube for the kids, but generally, spot fishing, not trolling, and a lot of cruising, I like my speed (I drive my SRT 392 like it is stolen) so I would aim for top speed most. So I am leaning to the Enertia, and it sounds like the REV 4 is better on multiple engines or 200 HP and up. But some sites say the REV4 is almost as fast, and is better on gas, and good for the odd time I will agree to tow the kids. My biggest thing is dialing it in as close to 5750, but again should that be under what load (just me of whole family) and therefore how to pick the correct D and P factoring all of this in. I don't want to lug or over rev the engine and risk long term damage. Any advice is appreciated as I want to order one ASAP as even though in over 30 years boating up there I have never hit anything, I want a spare on board, as well as a stainless as recommended by the manual.

  • #2
    We spoke about this one on email. I'd go with the Q3 16, we'll see how it goes.

    Ken Reeves
    [email protected]


    • #3
      I want to thank Ken for the instant response via email and now following up on the forum, reputation deserved. I am looking at this weekend for a few more trial runs to confirm the numbers and then will be in touch!