Addressing a leaky bronze shaft log

Discussion in 'Fiberglass and Composite Boat Building' started by ponchojuan, Aug 24, 2019.

  1. ponchojuan
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    ponchojuan Junior Member

    I have a 1966 28 ft. Henry Luhrs Flybridge Sedan I just acquired, .I believe it's the first year they made fiberglass hulls. The boat is actually in amazing shape for its age but addressing expected numerous age issues. An immediate one is a slightly leaking bronze shaft log. It's pretty worn and will need to be replaced eventually , but it seems structurally ok now and the bearing/seal looks relatively new. The bronze appears cast so its has a fair amount of interior hollow space making it difficult to trace the leak. It seems the previous owner had addressed the issue by packing the hollow with some kind of caulking .
    My thought is to clean it up, expose as much metal as possible, and then glass the whole thing up to the bellows. A can fill in the hollow with epoxy, wrap the tube with glass cloth and improve the support on the tube with some filleting. The idea is the stop the leak and improve structural integrity while not screwing with bellows/shaft and all that complexity creates.

    Any thoughts or experience doing this is appreciated. It seems the hardest part will be getting every thing really clean from bilge grease and getting the bronze shiny clean in the hollows.

    Thanks for any suggestions
     
  2. sdowney717
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    sdowney717 Senior Member

    I used my welding torch to re-braze the missing worn areas on my 2 shaft logs from where the prop shaft had been rubbing for 40 years.
    I was easy to to do with them off the boat.
     
  3. ponchojuan
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    ponchojuan Junior Member

    That’s probably the right approach. Hesitant to take the whole shaft assembly out of the boat . Never done that and a shaft alignment.
     
  4. kapnD
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    kapnD Senior Member

    I’d be looking for a replacement.
    Why put band aids on it when there is a certain fix that you are already aware of?
    This is a safety issue...
     
  5. missinginaction
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    missinginaction Senior Member

    A little more information would help. Is this a v-drive or is the engine in the center of the boat and just a straight shaft? I'm assuming that you're dealing with a traditional style stuffing box. Probably a small block Ford or Chevrolet engine? Something like a 1-1/4" prop shaft and a 1-3/4" stern tube? I did a complete restoration of a 25', 1973 Silverton Sedan which I still own. Replaced shaft, replaced old style stuffing box with a Packless Shaft Seal which was one of the best decisions I ever made. Engine alignment isn't that difficult once you get past the "I'm so scared to touch this" aspect of the whole thing. Provide some information and I'm sure you'll get some help here.
     
  6. gonzo
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    gonzo Senior Member

    The shaft/engine will not need to be re-aligned if you remove the shaft to reseal the log. Only if you were to change the strut that could be a problem.
     
  7. ponchojuan
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    ponchojuan Junior Member

    It’s a Chevy 350, Mercruiser. Borg Warner velvet drive, straight-line shaft 1 1/4 inch.

    I’m not sure an original replacement exists, it appears Buck- Algonquin has one that would work. I’m not sure it’s even the best design anymore. The unit is bolted externally on the bottom. A lot of exposed bronze and seams that can leak. My brother in law is a retired master welder from DuPont Research Labs. He has an amazing workshop and can make me a stainless unit during the winter.
    The plan right now is to glass the whole thing from the inside. Then replace it in a couple years when the transmission will likely get hauled and rebuilt. I’m still looking for a new OEM bronze unit .
     
  8. missinginaction
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    missinginaction Senior Member

    I went back and reread your original post. What "hollow" are you referring to? The only hollow area I'd know of is the clearance between the shaft and the inside of the stern tube. This would be filled with flax packing in a typical traditional packing gland arrangement. Without actually seeing a photo I'll go out on a limb as I think that most of these boats were of similar design. Your prop shaft passes through a 1-3/4" bronze stern tube. The stern tube is mounted in the boats "keel", which is fiberglass but I believe you will find is some type of hardwood on the inside. If you have an original there are probably 4 through bolts that hold a the stern tube flange at the rear of the keel, where the prop shaft exits the boat. It's bedded in with some kind of Sika or 3M sealant. I'll post a picture below looking through my shaft log from the inside of the boat with the drivetrain out of the way. Is this what you have?
    shaft log.JPG
     
  9. kapnD
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    kapnD Senior Member

    As a further stab at this, The photo in the avatar looks to be a hard chine planing boat, probably has little or no keel, and the log would be a flat cast bronze piece with a tube running through it at an angle. They’re usually bedded and bolted to the fiberglass hull.
    I’d remove it and replace with a glassed in fiberglass tube, to end corrosion problems and center it correctly so it does not rub anymore.
    Stuffing box is probably ok, just need some new packing and a new rubber tube.
    Some photos sure would help!
     
  10. ponchojuan
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    ponchojuan Junior Member

    It is constructed differently. Hopefully I can post some pics tomorrow. Basically it is an offset bronze casting with the tube running through the casting. The hollow area is on the interior.
     
  11. ponchojuan
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    ponchojuan Junior Member

    Thanks, that is what I thought.
     
  12. missinginaction
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    missinginaction Senior Member

    With regard to the alignment. I don't disagree with Gonzo often but in this case I have to. Your shaft may already be out of alignment. I found on disassembly that my packing gland was within a couple of thousandth of an inch from wearing through due to the engine and associated beds settling and causing the alignment to be pretty badly out. I ended up rebuilding the engine stringers. You may not have that issue (I hope you don't) but you'd be wise to check your engine alignment as you're addressing that shaft log. You may also find wear on the prop shaft, especially if it is the original shaft which would be made out of bronze. While everything's out look at the cutlass bearing and replace it. Not hard to do and you'll have peace of mind. One last thing. While you can stick with a traditional packing gland I'd really suggest that you replace it with a Packless Shaft Seal. With a PSS your boat can be dry, as in bone dry bilges. A PSS will also tolerate slight engine misalignment that a packing gland will not. The PSS is a wonderful advance in technology. Once you've installed one you never go back to a packing box.
     
  13. gonzo
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    gonzo Senior Member

    I can see that. Re-checking the alignment is always a good idea.
     
  14. kapnD
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    kapnD Senior Member

    The hollow in the stern tube Can carry a cutlass bearing if the shaft length between transmission and strut is long enough to warrant that. It’s often just an empty tube that carries the seal and keeps the water out.
    Yes, check everything from motor mounts to strut before doing any thing with the stern tube.
    I understand that the OP is looking for a quick fix, but when a stern tube is touching the shaft, it’s high time to figure out why and correct that problem.
     

  15. ponchojuan
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    ponchojuan Junior Member

    So the plan is to tear it apart and check everything out. As soon as my lower back is in order I'll do just that. No water time this first year but I was not expecting much. Things should be nice and tidy by spring.

    If the shaft log is as worn as I think ( its not rubbing but electrolysis) my brother in law is a stainless fabricator and welder and will make me one. Then I can get the shaft, hub, and prop refurbed too.

    Thanks fore help guys,
     
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