Cummins Marine Diesel Repower Specialists Forums All Other Marine Diesels Interpreting a propeller balance report

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  • #30975

    Bob Waters
    Participant
    Vessel Name: TunaciousToo
    Engines: Yanmar 4lha-DTE
    Location: Dana Point
    Country: USA

    Hello All,
    I had my propellers checked, repaired and balanced at Wilmington Propellers in Jan, 2016. The report said the propellers were 2″ off. I’m having a hard time interpreting the report for each prop.

    The Propellers are Michigan Hy-Torq, 18X24, 4 blade, #7 cup, 1 3/8 bore. The engines are Yanmar 4LHA-DTE @ 200 HP. The gears are ZF 450 A, 2.0 reduction. The boat is a Henriques 28 Express. The factory Tachs read about 150 high at 3,000 rpm, so tach at 3,000 rpm and photo tach is at 2850.

    Fully loaded, the engines go to 3,500 in flat seas. I interpret this to be 3350 rpm with tach error correction. Fully loaded is with 3 people and bait tank full. At light load, eg. bait tank empty and 2 people, the rpm hits 3550 and I think the governors are limiting the rpm. I think the current propeller setup is close. I run the engines at 3,000 (2850 real rpm), when conditions permit and speed is between 20.5 to 21.5 knots at full load. At light load, speed is 22.5 kts.

    Mechanically, everything is good with the engines. They have 1550 hours, all service is up to date.

    I think I need to take a little out of the propellers. The question is whether to adjust the current props or buy new. I looking at ACME props, but do not know what size to start at. I’m ready to do a haul out and now is the time to make the decision.

Viewing 3 replies - 21 through 23 (of 23 total)
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  • #31060

    Bob Waters
    Participant
    Vessel Name: TunaciousToo
    Engines: Yanmar 4lha-DTE
    Location: Dana Point
    Country: USA

    Hi Bill and Rob,

    The report came back from Basin Marine with the comment that “Pitch Varied 2”. To answer your question, Yes they are 24″ pitch, as stamped on the propeller.
    During sea trial, both engines ran up to the same WOT throttle and sounded the same when running at 3,000 rpm. If the rpm was different for each engine due to variation in prop pitch, I think the sounds would be different. They run very smooth and have a great sound.
    Rob,
    I agree that I need to drop some pitch. I’m worried about removing cup. When I talked to the builder, during sea trail about re-working the propellers, he stated “Do Not Remove Cup”. He has built about 75 boats with this engine combination. I guess I need to consult with Wilmington Propellers.
    I will be adding Aetna Tachs in the tower.
    Did you or Tony have an comments about the reports from Wilmington? The final numbers are much different from each other. I wonder if that is a product of LH and RH wheels?

    Thank you,

    Bob

    #31059

    Bill Fuller
    Participant
    Vessel Name: Audax
    Engines: Yanmar 4LHA-STE
    Location: San Diego, CA
    Country: USA

    Bob,
    When you say the propellers are 2 inches off, what is 2 inches off?
    Does that mean that the props are actually 22 inch pitch and not 24?
    With your setup, I would expect that 22 inch would be close, which is what you have, very close.
    Bill

    #31048

    Rob Schepis
    Forum Moderator
    Vessel Name: Tenacious
    Engines: 6BTA 5.9 330's - "Seaboard Style"
    Location: Long Island, NY
    Country: USA

    Nice engine & boat package. Yes, you’re wheeled a bit heavy. See attached. That’s a heavy cup, I would think dropping the pitch an inch and removing some cup (go to med cup aka #5) would bring you where you need to be. Consider Aetna tachs too.

Viewing 3 replies - 21 through 23 (of 23 total)

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