Cummins Marine Diesel Repower Specialists Forums Marine Transmissions Dripless shaft turning in current

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  • #69544

    Dave Galehouse
    Participant
    Vessel Name: Castalia
    Engines: Cummins 6c8.3
    Location: Mass
    Country: USA

    Launched my boat yesterday with no issues. A few hours later, the current in my river was at mid-tide and flows extremely fast. I was in the engine room and the starboard shaft started rotating and then eventually the port shaft. Boat is a 2005 Luhrs 36 open with twin cummins 6c 8.3’s with hydraulic transmissions and dripless shaft seals. This is the the third year with the boat and I do not recall the shafts ever turning in current. Mind you this is one of the fastest rivers on an outgoing on the east coast but it’s like that every year. There seems to be no consensus on the feedback I have gotten thus far about whether or not this is ok for the seals because there isn’t a flow of water into the seals with the engines off other than the residual water that is in the feed hose. They eventually stopped turning when the tide slowed down.

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  • #75455

    Bill Desmarais
    Moderator
    Vessel Name: Extremist
    Engines: Cummins 6BTA 370
    Location: Portsmouth, NH
    Country: United States

    Rob,

    Dave’s boat and mine are docked on the Merrimack River, Newburyport/Salisbury Mass.

    Dave, I have a PSS shaft seal. Prop shaft spins with the tide in my boat. No issues with the shaft seal.

    I was towed in on July 3rd, shaft must have been spinning a good 8 knots on the tow in with out going tide.

    I felt the shaft seal with my hand from time to time being towed. No issue with heat with the tow in.

    Since then, engine fuel leak fixed, 5-6 hrs on the boat since, NO issue with PSS shaft seal.

    Regards, Bill D

    #69552

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

    What river is she slipped on?
    What dripless setup, Tides, PSS, or ??

    #69549

    Bob Neill
    Participant
    Vessel Name: Moon Shine
    Engines: 6BTA 300 Hp
    Location: Point Judith, Rhode Island
    Country: United States

    Just my opinion, but I doubt the props are spinning fast enough to cause you any concern about the seals. When you launched the boat three years ago were the cutlass bearings new? Could they now be broken in to the point of allowing the prop to spin with the current.

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