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  1. #1
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    2019 ProXs 200 4s question

    Just recently purchased a 2019 ProXs 200 4s last week. Serial #2B597099

    I am currently still in break in with 4.1 hours. This has the 1.75 TM lower unit. So far the motor is great and impressed with how smooth it is.

    What is puzzling to me is how much smaller prop I am having to run to get the RPMs in the 6000 operating range. The older 2 stroke models are turning much larger 24-25 pitch props and a little more top end than what I am seeing. I know I am still in break in and maybe will loosen up a bit between 10-20 hours.

    The boat, a 2019 Triton 18 TRX came with a 24 fury. What we saw during testing was around 5400-5500 RPM, way short of the 6200 RPM redline. We ended up dropping to a 22 Tempest Plus and this currently is around 5900-6000 RPM (vessel view) and 68-69 mph gps.

    I have heard that the new lower units are more aerodynamic and efficient and that the V8s have more torque so it surprises me that they cannot turn a larger pitch prop to meet the optimal operating range than what we are seeing. Then again 200 horsepower is 200 horsepower either in 2s or 4s.

    Thoughts?

  2. Member idratherbeefishin's Avatar
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    #2
    The 22 or 23 pitch seems to be the prop of choice. I have around 57hrs on mine now had it for a year and I love it . Less moving parts in a 2 stroke so it's easier to turn the prop. I have a 23 fury on my nitro and it took some testing but 2.5 ptp and it consistently turns 5900 RPMs 66 mph in warmer water. When the water cools off it was hitting 68 mph last winter and rpms will pick up some.

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    #3
    It is ALL in the gear ratio. And along with RPM being slightly increased.

    In the past this had caused confusion on Nitro boats back in the 90's when they switch from Johnson/Evinrude to Mercury on the same model boat. Same model of boat about the same RPM but required drastically different prop pitches between the two. As you can imagine, that it caused massive confusion when guys asked for setup questions on the same boat models. And question was not asked, Evinrude or Mercury. Putting a 24p on a Johnson was NOT going to work. Mostly seen this with the 115hp motors.

  4. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #4
    Not just the gear ratio- the SLIP numbers (overall) are considerably lower on the newer TM gearcases (as compared to those of "yester-year".

    Essentially- you have to drop at least 1 pitch point JUST due to the improved slip numbers.

    10 years ago, it was nearly unheard of to see a 6% prop slip. Today... actually quite common.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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    #5
    My Pro XS 200 four stroke is on an aluminium boat but I'm going through the same process. I started with a 21 p Laser II that I already had because I was using it last year on another boat with a Verado 250 Pro XS. Could barely turn 5300. Went to a Tempest Plus 19 p to get he rpm to 5600-5700 but the boat is porpoising a bit. Thinking of going to a 17 p but not a lot of choices.

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    #6
    Quote Originally Posted by EuropeanAM View Post
    10 years ago, it was nearly unheard of to see a 6% prop slip. Today... actually quite common.
    Hey Don, totally agree, but unsure as to why, do you have insight on why? Is it better hydrodynamics of the Lower Units and Gear Case Housings, Better Boat Design, better prop design?

    My own boat's slip calculations seem to be in the 7-9% range...so totally agree.
    2016 Ranger 1850 LS Reata / Merc 150 4s / SmartCraft / Lowrance HDS Carbon SS3D

  7. Member
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    #7
    Yes better hydrodynamics not aerodynamics. Last time I checked I was getting 5-6% slip which is great.

  8. Member
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    #8
    Also sounds like there is an emerging market for some new prop designs better suited for these motors.

  9. Member
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    #9
    Your numbers do NOT add up. 22P at 5900/69 mph is a 2% prop slip. Very unlikely. Something is wrong. Is the tach digital or analog? If analog, the RPM numbers don't mean very much.
    2008 Bass Cat Pantera Classic
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  10. Member
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    #10
    Oldtimer57, sorry a little more info for detail. It was 66.5 at 5910 and digital tach and gps. The vessel view showed a top speed of 69 but the only time I caught both RPM and MPH was the 66.5 and 5910. I also saw 67.5 but didn’t catch the RPM.

    Also measured my ptp 3.25”.
    Last edited by DaveTTN; 07-18-2019 at 07:52 PM.

  11. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
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    #11
    Quote Originally Posted by MichaelJ3 View Post
    Hey Don, totally agree, but unsure as to why, do you have insight on why? Is it better hydrodynamics of the Lower Units and Gear Case Housings, Better Boat Design, better prop design?

    My own boat's slip calculations seem to be in the 7-9% range...so totally agree.
    Hydrodynamics- a large portion of which is the unique gearcase strut area/design.


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
    Mercury Parts, Mercury Outboards, Smartcraft & Accessories, Injector Service, TDR Reeds- BBC Sponsor