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Thread: Possible prop changes from 28ZX ???

  1. #1
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    Possible prop changes from 28ZX ???

    Have 2001 28ZX w/ twin 350s
    Both run good
    Have 3 Blade props @ this time & thinking about changing to (5 blade hydromotive P-5X 28" props)
    My top speed @ this time is approx 60mph

    Can anyone give me some insight regarding these props
    How much do you think it will help w/ plane out & top speed ???

    Can e-mail direct to:
    stationinc@aol.com

  2. #2
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    I have a prop thread going in the donzi section of Offshoreonly. Probably worth reading through.

    Something is wrong with your speeds.... at what RPM do you see 60? What 3 blade props do you have now specifically?

    My assumptions (correct me if I am wrong please)
    • closed deck version, not the open bow
    • 1.5 ratio drives
    • No bottom paint
    • Things are running properly overall


    Assuming that is what you have your best top speed will be had with 23 inch Mirage Plus props. That should get you to 70 MPH plus or minus based on conditions/load/etc.

    If for some reason you have a different setup post it up and we can help more.

    As far as the 5 blade... they will get you a great cruise but slow you down for top end. Really, the Bravo 1 4 blade is a great cruising prop on this hull (that's what I use 95% of the time). They pull 5-ish MPH off of the top end though resulting in 65-ish for me (6.2, open bow, 1.65 drives so kind of a different boat)

    With the assumption list above you'll never turn a 28" anything. If you went to a 5 blade you would be looking a 21 inch and no more than 23 inch. I'd think a 24 Bravo 1 might be a good fit as an alternate, they are also all over for sale and much cheaper.

  3. #3
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    +1 on what Vette wrote. Bill

    1971 Donzi 18' 2+3
    1985 Eliminator 23' Daytona Offshore - Kevlar hull
    1988 23' Donzi CC F-23 with 250HP EFI Mercury OB
    1989 28' Team Warlock Offshore - single 548CID/600HP
    1990 23' Warlock Offshore - single 525HP
    Bill from Denison, TX - Lake Texoma

  4. #4
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    Lightbulb

    +2 on the above!

    Once you are sure your power is up to snuff get yourself to one of the Donzi gatherings, all boats react differently with props. You will be ahead of the game trying before buying. Many setups are a slower with 4 and 5 blade props, my setup ended up being faster with a 4 blade go figure.

    Phil
    No matter what your beliefs are "GOD BLESS AMERICA"

    Semi retired marine tech over 50 years in the biz.

  5. #5
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    Possible prop changes from 28ZX ???

    Thanks for all of th response letters:

  6. #6
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    Possible prop changes ???????

    Thanks for the responses:

    The boat is a ZX closed bow
    1.5 drives
    Not painted, fiberglass & like new
    Thisngs seem to be running properly
    60mph @ approx 4000 rpms (depending on the condition)
    I have 23 props on the boat now

    I WILL SAY >>>>> this boat burns gas like no other boat or vehicle I have ever owned !!!!!!!!!!!!
    Now I am wandering if it is tuned properly ???????
    Thoughts ??????

    stationinc@aol.com

  7. #7
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    Your RPMs are way off. What kind of 23" props do you have, Mirage Plus? I'll assume so for now because that's what the factory put on the boat. I'll take another guess that this isn't GPS speed?

    My gut says your engines are throwing codes and the Merc computers are limiting the RPM in guardian mode. You are probably running an actual speed of 55-ish. Your engines should turn to 4800-5000 RPM. That's why your speed is lacking.

    Run a scan on the computers to see what is going on

  8. #8
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    Quick supplementary question: what are the motors, exactly? (I saw they were 350 cu in, but what model/HP? Sorry if it's there and I missed it.)
    "I don't have time to get into it, but he went through a lot." -Pulp Fiction

  9. #9
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    Does the trim work? You should be able to get the prop to slip with the trim. If it won't rev over 4000 RPM period . You need a scan tool not a prop
    machinist ,bore it deeper,ream it bigger, and lap it to a fine finish



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