Wet keel northern Bay 36 - surprise on launch

Discussion in 'Downeast Projects and Boat Building' started by backman, Apr 16, 2019 at 8:42 PM.

  1. backman

    backman Captain

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    so I sort of knew my Northern Bay 36 had a wet keel first by the fact a lot of water came out of the stern tube each time I was hauled and second by the fact that a crack in the joint between thr jeel ans the skeg dripped water all winter long.

    My yard added a steel shoe to protect the skeg this winter. When they drilled the bolt holes for the skega lot of stale water, maybe 10 gallons worth ran out, mor evidence of a wet keel.

    And then I launched last week and found this surprise while inspecting spaces while still in the slings.:

    The leak is above and behind my shaft log and is from one of 4 3/4” screw holes that were where my raw water pump used to be be before I relocated it 4 years ago. Those holes were plugged by sealant when I relocated the pump, and one of the plugs blew out on launch this year.

    While on the hard while the holes were glassed in I spent some time below the boat and realized that flat space behind the shaft log is a false bottom above the wet keel which extends about 3’ in length and 2’ in depth. You can see the holes behind the log in the picture.

    Who knew!
     

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  2. ArchHibb

    ArchHibb Captain

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    Thar she blows!

    It looks like you have a shaft tube, but if yes then how is water getting into the wet keel cavity? Through that crack you mentioned between the skeg and ?
     
  3. backman

    backman Captain

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    I don’t know. My assumption which the yard also believes is that the water gets in between the shaft tube and the keel opening and fills that compartment. Obviously taking a Sawzall to it is not the answer! Adding the shoe wasa change this winter, but my performance and fuel burn is constant. This has been going on a long time, especially it’s the stale water pouring out of the keel when the holes were drilled.


    The yard owner had a Libby and Duffy, one of which was a wet keel and had vents for the water to flow out of. He thinks this is “normal” and was not shocked when the water poured out.
     
  4. Genius

    Genius Captain

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    a wet keel boat and a boat with a fiberglass shaft log are two completely different set ups. I'm getting a feeling that something is getting mixed up here?

    Do you have a picture of the deadwood where the shaft exits the keel?
     
  5. backman

    backman Captain

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    Here is a shot . The shaft was removed in 2013 and a pair of cutlass bearings replaced. I know the rear one at the deadwood has a couple holes for set screws to hold that bearing in place. They were faired over with bonds when that was done. Water is definitely entering and draining via the cutlass bearing. As I mentioned when the boat is hauled, water pours out that bearing, many gallons worth, far more than would be in th3 log alone. I should also mention water came out of the forwardmost two bolt hole for the shoe, the aft ones were dry.
     

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  6. Genius

    Genius Captain

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    oh boy. I think you may have to cut that space open from the inside to take a look at what is going on. The fact that water is draining out the shaft log means that there is communication between the keel void and the log. I can't speculate why that would be???

    Edit: maybe it's just the saltwater left in the engine that is draining out the shaft supply tube? Not the void area. Maybe reseal the bolts to the skeg guard with 5200 and have an inspection hatch to the keel void space?
     
    Last edited: Apr 17, 2019 at 8:19 AM
  7. Blitzen

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    A boat without a shaft tube will have a wet keel, holes on either side of the keel to allow water in to lubricate and cool the bearings. This water will drain out the same holes when the boat is hauled out.
    A boat with a shaft tube should have a dry keel void space where the tube passes through the keel. The bearings are cooled and lubricated by a water feed on the front side of the tube and exits at the prop. Not sure how the water you are seeing is getting into the tank but it could be as simple as bilge water finding it's way in. Surprised you never noticed condensation on the keel on those warm spring days.
     
  8. ArchHibb

    ArchHibb Captain

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    A wet keel and a shaft log are just two different shape containers for the lubricating seawater. Genius is right; there shouldn't be any communication between them.

    The video of the seawater spurting up from the keel void tells you all you need to know; there is a connection between the ocean and your keel void. The question is whether the water is entering the shaft log and then breaching into the keel void, or leaking directly into the keel void through a crack in the keel outer surface, or both.

    Sealing off the keel void from the hull interior, as you've done with those screw holes, eliminates the sinking :eek: but now you need to either a) find the breach into the hull void and plug it or b) add a drain plug to the keel. You don't want water stagnating in the void nor freezing in the winter.
     
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  9. ArchHibb

    ArchHibb Captain

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    Bilge water would have to leak in through the stuffing box, correct? To my eye, the spurting seawater is proof that the keel void is somehow connected to the outside (ocean).
     
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  10. Genius

    Genius Captain

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    yes, connected to sea most definitely.
     
  11. Blitzen

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    So if the bulkheads that make up the tank are not entirely watertight it is possible that the partitions allow water into that tank. The spurting water could mean a connection to the outside and free flow of water or is it possible the tank was full of water and under pressure from the boat being in the water forcing the water out the screw holes. I don't know.
     
  12. Blitzen

    Blitzen Captain

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    I guess the question would be, did the water ever slow down or stop when it was discovered?
     
  13. ArchHibb

    ArchHibb Captain

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    ^ That, and more importantly, what did it taste like? :p

    Backman, you're in for the season now right? If so, and since you haven't had any negative issues in the past, I would go through the season as you are now. When you're next in the slings, just before hauling, drill a hole in the area where the pump was and find out if the water that comes out is fresh or salt. You'll then know where to look for the source.

    You could also observe that water for any difference between when the engine is running or not. If the shaft log is in fact leaking into the keel void, the water flow from the hole you drill should be greater due to the pressurized water coming from the shaft log.
     
  14. Keelboater

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    This is an odd duck. Do you think it's possible that the water being fed to the front of the tube at the dripless seal is not enough to provide coolant for both of the cutlass bearings? Perhaps the rear cutlass bearing had a very short life and somebody modified the hull in such a way to get additional water to it? Other than that, I have no clue why this would be so unconventional. Apparently it works, but I know I would have already taken my sawzall to it just out of curiosity. :D
     
    Last edited: Apr 17, 2019 at 9:03 AM
  15. Genius

    Genius Captain

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    I just reread your first post. You mentioned a crack between the skeg and the keel. This is why the extra skeg protection was added. It sounds like that crack was never fixed?

    You could put some drain holes in the top and bottom (both exterior like a real wet keel boat) of the void space and treat it like a wet keel for the short term or....long term (i wouldn't). This would require that the mounting holes that were leaking water in the video be properly glassed up.

    Like ArchHibb said, if you don't want to haul out...temporarily screw in some bronze screws coated in 5200 to the leaking holes.

    Personally, I don't like these voids in boats that do not drain to the bilge, have some access/inspection hatch or alarming device.
     
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  16. backman

    backman Captain

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    Thanks all, I now have a plan thanks to your advice. I typically short haul and bottom blast in early July right as my offshore season starts. I will continue to observe till then, then when I short haul, drill an inspection port, come up with the plan, then execute the plan next winter.

    I had already come to the conclusion the shaft log is breached in some way, either at its ends or via an internal crack. There does not seem to be any communication between the void and my bilge, my bilge holds the same 1/2” of water for the 7 seasons I have owned the boat. If there were cracks, it would have filled the bilge and engaged the pumps as was the case with the spurting water.

    The crack between skeg and hull has been ground and patched at least 3-4 times, thus the addition of the shoe as our conclusion is that the skeg is moving which is obviously not s good thing.

    We did reseal the bolt holes when I short hauled after finding the leak, can look again July. Also, the leaking holes were properly ground And glassed during that short haul.

    Thanks is again for the help!
     
    Last edited: Apr 18, 2019 at 7:00 AM

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