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Overheated Blue Water Shaft Seal

Discussion in 'Props, Shafts & Seals' started by Capt Maritime, Jul 20, 2022.

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  1. Capt Maritime

    Capt Maritime Member

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    While bringing my Cabo 40 north from Key Largo to Virginia Beach the starboard shaft seal, which is a Blue Water seal, overheated due to loss of cooling water. The fitting off the heat exchanger was clogged with scale and while underway the seal started to scream loud enough that we heard it on the bridge. Engines were placed in neutral and the seal was very hot to the touch. After trouble shooting I determined the cooling water line from the engine to the seal was not flowing any water as the fitting off the heat exchanger was plugged with scale. After removing the scale and flushing the line we were underway again. No hot shaft seals for the reminder of the trip. Both shaft seals are running cool, however the starboard seal leaks underway. As I am not familiar with these types of seals, what internal damage is likely due to the overheating issue?

    Attached Files:

  2. mapism

    mapism Senior Member

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    In principle, overheating can damage all dripless seals, potentially to the point of needing to replace/refurbish them.
    But among the two broad categories, i.e. face seals and lip seals, with the latter also the shaft is more likely to suffer.

    Now, I'm also not familiar with this Blue Water thing, but from your photo I would think it's a lip seal.
    Bottom line, in your boots I'd like to have it inspected by someone who knows it inside out.
    Which might require a liftout, I suspect.
  3. Capt Ralph

    Capt Ralph Senior Member

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    I have learned more about these Blue Water seals. Seems you can not place a spare seal on the shaft. I fear, once an issue, the shaft has to be drawn and new seal installed.
    The real sad news, You will not know of any shaft damage until the shaft area is exposed.
    BUT, changing the log hose length, quickly fixes this issue IF any damage has accrued.

    On other threads on YF, some members take this first failure as the time to install a more serviceable lip seal system with service spare seals already on the shaft.
    This is something to think about, real hard thought if operating in shallow or silty water.

    Glad your home safe. Glad this was your only issues.
    Keep us up on your decisions on this and any other work on your new ship.

    I was hoping to design a serviceable cover plate by now, just have not got to it.
    Anybody want to give it a try. Our Bert has required some un-expected work. Freaking fresh water....
  4. mapism

    mapism Senior Member

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    CR, do you mean because they are actually face seals, which by definition can't be fitted with a spare, or are they lip seals but for some reason it's impossible to leave a spare or two on the shaft, ready for replacement also in the water, as for instance in Tides Marine lip seals?
    Just curious to know if my guess about them being lip seals was right...
  5. Capt Ralph

    Capt Ralph Senior Member

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    Good picture in this thread;
    https://www.yachtforums.com/threads/shaft-seals-and-cutlass-bearing-life-expectancy.31248/

    Post #10 from CSkipR.
    It looks like a regular shaft gland that would have flax or Gortex compressed in it.
    But that plate just holds a seal and bushing.
    Last edited: Jul 21, 2022
  6. mapism

    mapism Senior Member

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    Thanks CR, I must have missed that thread altogether.
    A lip seal it definitely is.
    In the OP boots I'd want to have both the seal and the shaft inspected, and at least the sealing bits replaced.
    Which can't be done with the boat in the water, I'm afraid...
  7. Fiammetta42

    Fiammetta42 Member

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    Looking at the pic I notice overspray on the pipe .Not related to your issue , but as a side issue I never like to see it because it tells me the machinery has had a quick DIY ( arguably incompetent) blow over with a rattle can prior to sale .
    It will wipe off with thinners/ actetone etc when you have a minute.
  8. Capt Maritime

    Capt Maritime Member

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    I am very particular about the engine room. The overspray on the hoses will be addressed in the near future. Getting the vessel home was the first step, followed by some mechanical service, then in time retuning the engine room to like new condition.
    Fiammetta42 likes this.
  9. Capt J

    Capt J Senior Member

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    You can put 1 ring of traditional packing in the chatfield dripless seal for now to stop it from leaking temporarily until it's hauled.
  10. Capt Maritime

    Capt Maritime Member

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    Strange thing with the stbd shaft seal that overheated on the way up from Key Largo to Virginia Beach, it is running nice an cool almost the same temp as the port. It stopped leaking while underway as well. So I'm thinking maybe the seal and shaft will be ok. So when I haul the boat I'm thinking of overhauling the seals vice replacing with PSS. The extra ring of standard flax packing is a great back up option.
  11. Capt Maritime

    Capt Maritime Member

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    Quick update - the stbd shaft seal that overheated is running nice and cool now, plus it has stopped dripping underway as well. Both seals will be disassembled and rebuild when I haul out later this year. Interesting photo...before and after. STBD Shaft Brush 1.jpg
  12. Capt J

    Capt J Senior Member

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    Price out replacing them. A guy had new ones on ebay for not much money. They're good seals though.
  13. DOCKMASTER

    DOCKMASTER Senior Member

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    I have those same shaft brushes. Curious what the benefit of doubling the bonding wires is to each of them?
  14. Capt Ralph

    Capt Ralph Senior Member

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    Daisy Chained. The cables split Y out of sight.
  15. Capt Maritime

    Capt Maritime Member

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    The original Cabo lip seals have been removed and thankfully I do not have any damage to the stbd shaft due to the overheated lip seal. New PSS Pro shaft seals should be installed this week. Stbd inboard shaft .jpg
    bayoubud likes this.
  16. mapism

    mapism Senior Member

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    Great choice, you won't regret it.
    Out of curiosity, are you possibly aware of the price difference between the pro and non-pro versions?
    I like the additional clamp of the pro in principle, but actually I never heard of problems also with the non-pro version without it.

    PS: excellent cleaning job, gotta love an immaculate bilge! :)
  17. Capt Ralph

    Capt Ralph Senior Member

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    I got a note on this last week.
    Seems that first version stainless collar has slid up the shaft a few times. Some boats got wet.

    So, the new pro kit includes that locking mini collar.
    Also, installation and service kits now include set screws that will bite into the shaft and a tube of LocTite.
  18. Capt Maritime

    Capt Maritime Member

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    New PSS Pro shaft seals installed. I completed a satisfactory sea trial. Working great. Cabo launch day 18 Nov 2022 port PSS Pro seal.jpg Cabo launch day 18 Nov 2022 stbd PSS Pro seal.jpg
  19. Capt Maritime

    Capt Maritime Member

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    Well I just bead blasted my old Cabo/Blue water seals. They cleaned up nice. I may rebuild them with new lip seals and hold on to them.

    Cabo Bluewater Lip Seals blasted.jpg
  20. RBaker

    RBaker New Member

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    Captain Maritime,
    Are you interested in selling one of those ?