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Water in propeller tube

Discussion in 'Technical Discussion' started by Capt Fred, Jul 13, 2014.

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  1. Capt Fred, Jul 13, 2014
    #1
    Capt Fred

    Capt Fred Senior Member

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    Captains and engineers, I'm working on a Warwick 21 meter, Aluminum hull sailboat with water in the propeller tube. The tube is sealed with lip seals, two bearings and runs in oil. All were replaced at haul out just a few months ago. We recently noted water in the tube and there has not been more than a few hours of running since the haul out. I'm new to propeller tubes, is this indicative of a problem with the seals or should one expect some water leaking into the tube. Thanks
  2. captholli, Jul 13, 2014
    #2
    captholli

    captholli Senior Member

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    Hi Capt. Fred,
    There shouldn't be any water in your oil bath drive. Do you know the manufacturer? Do you have a thrust bearing behind the gearbox? Do you have temp sensors on the system and is your oil header tank milky? Other than the stern seals, you might have a pressurized coupling if you have a tail shaft that could have lost its nitrogen charge allowing water ingress. pure speculation at this point not knowing the make and mod.
  3. K1W1, Jul 13, 2014
    #3
    K1W1

    K1W1 Senior Member

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    There can be a number of ways for water to get into the oil.

    If you use a good quality stern tube such as Vickers Hydrox a bit of water will not do any harm.

    How does the oil circulate in your arrangement?
  4. captholli, Jul 13, 2014
    #4
    captholli

    captholli Senior Member

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    I can only assume that your vessel would have a cam pump or a "Knock Pump"
    that runs off the prop shaft rotation Fwd. of the thrust bearing if one is fitted? Since its on a smaller install aboard a sailing vessel does it have a cooler or heat exchanger? Besides the header tank, is there an expansion / overflow tank aft? Manufacturer is key here, I see that your vessel was built in N.Z. Now they're building in Turkey?
  5. K1W1, Jul 13, 2014
    #5
    K1W1

    K1W1 Senior Member

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    Hi,

    If he had an Akerboom one maybe but as there are others out there that use no pump it is probably best to wait for the answer before making assumptions wouldn't you say?
  6. captholli, Jul 13, 2014
    #6
    captholli

    captholli Senior Member

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    Akerboom hasn't always used cam pumps but changed from electric to mechanical in the early eighties. Up to that time they used electric pumps and sea water cooled heat exchangers as I was the Chief on the Feadship "Daria"
    in 1979-80 (a little before your time as an engineer) & we had issues with the electric system and had to retro fit. I've come full circle as I've just finished up on the Feadship "Iroquois" three months ago with the mechanical Akerboom system and since this sailing vessel was more than likely built in N.Z. then who knows BUT, for your personal interest there are other systems that use cam pumps as I type this like Wartsila and Federal so yes , I'm speculating as to what system this gentleman may have aboard but am only trying to help narrow it down if he doesn't know and in no way do I need to be chastised or reprimanded by you. You have many posts on YF but by no means are you the Wikipedia of YF but you and two others here seem to take a certain amount of satisfaction trying to poke holes in others attempts to help other members. Chill out K1W1...
  7. Old Phart, Jul 13, 2014
    #7
    Old Phart

    Old Phart Senior Member

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    I dunno
    Some people cannot see the forest for the trees.

    Others do not realize swiss cheese is full of holes.

    Interestingly, sometimes it is necessary

    to enlighten someone to these simple truths.


    P.S.- Food for thought.

    Cat sold 1693's with defective liners.

    Told owners oil consumption was normal.

    How many Cat certified mechanics knew?

    Hint: In 1979 - 1980 = none, who were talking.
  8. Capt Fred, Jul 15, 2014
    #8
    Capt Fred

    Capt Fred Senior Member

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    Hi all: I do not know the manufacture. The temp of the tube was at 70 degrees F, basically seawater temp. There is a thrust bearing fwd of the tube. The tube has a reservoir. I do not see a pump or a way of pressurizing the tube. The vessel is hauled out and the mechanics will begin the diagnosis. Will keep you up dated, again thanks for the great help. Fred