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Thread: Prop selection for Merc 50hp EFI BigFoot

  1. #1
    Join Date
    Jul 2020
    Location
    Canada
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    5

    Default Prop selection for Merc 50hp EFI BigFoot

    I have a 2014 Harris Cruisers 200 with Mercury 50 EFI BigFoot. AT WOT using 4 blade 13 7/8" x 13 P with 2 people on board, full fuel, I get 4100 rpm at 17.4 mph per Gps. Any suggestions for new prop?
    Last edited by BigI; 09-05-2020 at 06:30 AM.

  2. #2
    Join Date
    Feb 2014
    Location
    Boat at Lake of the Ozarks Missouri
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    Well I think 5500 - 6000 RPMs is the Manf. range for this engine.
    It has a 2.3 ratio gear case so I would drop down an inch or two in pitch.

    I think 4100 RPMs is way too low. Is your Tach accurate ?

    First of all 4 blade is always my choice as it wont blow out in the turns, it bites quicker on hole shot
    and it smooths out the RPMs at cruise. BUT you need the right 4 bladed prop.

    If you are OK with Aluminum, and you should be from a price stand point, then try a 13.5 x 11 Pitch and you should be right in the sweet spot.

    I noticed you quoted your 4100 RPMs with a load on. That's smart as props get expensive and you don't need to buy 2 just to get 1 you like.
    Be wary of unloaded RPMs as you don't want to overspeed that 50HP when alone. I'd rather be underpropped a bit than over on a solo run.


    Try Mercury's prop selector website at
    Prop Selector - Quicksilver Productswww.quicksilver-products.com › marine › propellers

    or https://www.mercurymarine.com/en/us/...lers/selector/

    Let us know how it works out.. Sometimes, a good dealer will let you
    test a few props if you promise to buy the final selection from them.
    Last edited by Captain Tony; 07-24-2020 at 01:38 PM. Reason: updated info
    Captain Tony
    2005 Summit by Triton - 220T Platinum 3Log
    2005 115HP Mercury Optimax - 228 Marine Master Trailer
    St. Louis & Lake of the Ozarks, MO.

  3. #3
    Join Date
    Jul 2006
    Location
    Raystown Country, PA
    Posts
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    I have an 11p on my carbed 4 stroke 50 Merc, not BF but 1.8:1 lower, on a 19 foot Forester, WOT with 2 adults 4 kids is 18 MPH GPS, no tach until new console is installed. You should get your revs up closer to that 6K mark and you will probably find a little speed, but not a lot.
    2006 Forester 19 Fish (new deck and carpet, Pontoonstuff interior, 2019)
    1996 Mercury 50 ELPT4S
    1983 Sea Nymph FM171 Striper (complete rebuild from hull up, 2014)
    1985 Johnson 70 J70ELCO

    Raystown Country, PA

  4. #4
    Join Date
    Feb 2014
    Location
    Boat at Lake of the Ozarks Missouri
    Posts
    634

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    Thanks Larry:
    The 11 pitch seems to be right in my calculations. As to diameter, well see what Mercury has in the 4 bladed 11 pitch prop.

    I'd think it's around 13 or 13.5 inches. REMEMBER you are in a 4 bladed prop so don't forget you
    lose @200 RPMs because of the 4th blade.

    Still, try to go for the high end of your power band at WOT and it will be comfortable at cruising.

    I like @ 3600 to 4000 RPMS cruise which give me 30 MPH give or take a MPH.
    If I want more I've still got some throttle left.
    Last edited by Captain Tony; 07-26-2020 at 05:42 PM. Reason: spelling
    Captain Tony
    2005 Summit by Triton - 220T Platinum 3Log
    2005 115HP Mercury Optimax - 228 Marine Master Trailer
    St. Louis & Lake of the Ozarks, MO.

  5. #5
    Join Date
    Jul 2020
    Location
    Canada
    Posts
    5

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    Well yesterday I had a chance to try my new 14"x9p 3 blade prop(Black Diamond). RPM maxed out at 6100 but top speed stayed the same. Will order today 14"x10p 3 blade (4 blade not in stock in Canada) and see what happens.
    Last edited by BigI; 08-02-2020 at 06:33 AM.

  6. #6
    Join Date
    Jul 2020
    Location
    Canada
    Posts
    5

    Default

    Well yeaterdayI finally got to install and try my new prop. It is a Turning Point Hustler 14"x11p 4 blade unit imported from US. Can't beat that price. The testing conditions were less than ideal with a 1 foot chop. Two people, half fuel and little gear at WOT it spinns at 5200 rpm and toped out at 18.7 mph. We cruised at 4100 at ~15 mph comfortably in the chop and wind. I guess a 10p would be even better but maybe next year, for now it's a keeper. I speculate under ideal conditions it may spin and go a bit faster. Note: In my first post I was converting speed from kph to mph (being in Canada metric) and made an error that I now corrected. Also I set my GPS to read in mph so no conversion this time.

    Last edited by BigI; 09-04-2020 at 12:37 PM.

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