Shaft tube replacement

Discussion in 'Downeast Projects and Boat Building' started by speedwagon, Jun 7, 2019.

  1. speedwagon

    speedwagon Senior Member

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    The project started as a simple cutlass replacement but after pulling the bronze stern tube and getting a good look at the amount of corrosion inside, I decided to retire it and install a fiberglass tube. 20190409_161414.jpg


    Thankfully many here have posted some great info and I've linked a few threads below that I've looked to for advice.

    Replacing Stern Bearing Housing and replacing with a FRP shaft tube

    lossing the log and giving the shaft a tube

    Shaft logs

    After speaking with Rose's and reviewing available tube diameters, I decided to make my own tube to $ave and to match the orifice in the keel. 20190413_122327.jpg

    The 1708 was wet out on the table and then rolled onto the steel mandrel. It worked out ok but the fiberglass became bunched at the edges. In the end it didnt matter because the edges were cut off. It was a major pita to remove the mandrel. I ended up having to pull it out using two cars.
    20190411_103244.jpg
    The tube is at the machine shops now being bored and faced.
     
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  2. Ol Gilnetter

    Ol Gilnetter Senior Member

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    You doing that work in the kitchen? Any chance you grabbed a video of the two car mandrel removal episode? Looks good thus far.
     
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  3. BillD

    BillD Captain

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    ambitious !
     
  4. El Mar

    El Mar Captain

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    Nice!

    What di you use for a Mandrel?
     
  5. Keelboater

    Keelboater Captain

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    That's hard core! What's the finished wall thickness of the tube? I have been up against the same crap on my boat and have now planned the same thing, but I'm not making the tube. I plan on dropping the shaft to swing a larger wheel and modifying the keel while I'm at it. I figure while I'm in there with everything apart at the moment, I might as well do it right. Keep posting pics on this as you go. Thanks and good luck.
     
  6. speedwagon

    speedwagon Senior Member

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    Yup that's a kitchen. I've cooked up some good stuff in there.

    No pics of the pull but it looked ridiculous on a busy residential street in providence. I used my old station wagon as an anchor with the engine on in neutral and the wife on the brake pedal. I pulled with the truck, all it took was some light throttle and pop. Chains between all.

    Steel electrical conduit. It's the only thing I could find cheap that was close to the required i.d. Wrapped with thin polyethylene as a mold release, big mistake should have used mylar or something stiff.

    The finished wall should be around 5/16" but less where its bored for the bearings. I'll add glass at the critical areas where it gets stuck to the hull and bulkhead.

    That's smart to drop the shaft for the bigger wheel. Guess you just jack up the front engine mounts to compensate. I think the only drawback with what I'm doing is I'm stuck with the geometry I have. I did set the i.d. so I could upgrade to a larger shaft for a repower.
     
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  7. Keelboater

    Keelboater Captain

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    Cough.........It's a Meth lab...........cough cough ;) Your wife is hard to come by. If she lets you "cook fiberglass" in the kitchen, she's a keepah!

    Yes, the front of the motor in my boat needs to be raised about 7/8" to get the shaft down 3" at the prop. Required deck clearance in the wheel house just makes it. :)
     
  8. Genius

    Genius Captain

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    don't beat yourself up about the mold release material. PE shrinks as it cures, anything used as a mold release would not have worked easy. Definitely following this thread! You and Keelboater do know it is June already?:)
     
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  9. Bill

    Bill Administrator

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    Love this, I looked at the FRP tube they sell on Grainger but didn’t have balls to glass it in and then have it not work..
     
    Bill,
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  10. Snake8

    Snake8 Member

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    I used carnuba car wax recently on a couple projects as a release for bearing mounts and it worked awesome. I was using epoxy.
     
  11. c1steve

    c1steve Senior Member

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    Powderpro recommended a flanged cutlass bearing with pre-bored stern tube. This sounds like a great idea. Cutlass bearing comes out easily and the stern tube is built up at the aft end a pre-bored.

    NEW 35' Duffy Build

    If I was building a stern tube, I would use vinylester or perhaps epoxy. This area is constantly submerged, is not painted, and difficult to replace. No point in taking any chances.
     
  12. speedwagon

    speedwagon Senior Member

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    Thanks for the that. I hadn't read that one. That's a nice system.

    Some parts came back from the machinist. Here's a look at the aft end of the tube with the cutlass projecting 1/2" so I can grab it with channel locks for removal. 20190608_125201.jpg At the minimum I'll use three set screws set at 120 degrees apart and some epoxy or similar at the edge of the interface. But what I'd like to do is have the machine shop fabricate a bronze cap for the end of the tube that would help secure the cutlass, something like what RE Thomas makes. Here's a sketch of what I'm thinking, the cap is the solid black piece. 20190610_171137.jpg It would probably thread onto the end of the cutlass and fasten with screws into the fiberglass tube that would also bind the cutlass. What do you guys think?

    After much deliberation I decided to use the old stuffing box. If I ever decide to hard mount the engine I can ditch the stuffing box and put a dripless and cutlass in the forward end of the tube. I did have to build up the o.d. of the stuffing box with fiberglass to match the o.d. of the tube. I had the machinist turn it down and drill and tap for a water feed. The brass fittings will be changed to stainless. 20190608_125615.jpg
    I've started cutting up the keel. I'll post some pics once I make some progress.
     
    Last edited: Jun 11, 2019
  13. speedwagon

    speedwagon Senior Member

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  14. Keelboater

    Keelboater Captain

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    If you have a lathe handy, thread the end of the cutlass bearing that will be protruding out of the tube and make a threaded bronze flange that threads onto it. The flange should have 3 tapped holes in it for removal screws when the time comes. You can still use the stock set screw location for locking the bearing in place. This assumes that the bearing has a thick enough metal wall for threading. End result will look similar to a factory flanged bearing, but to my knowledge are not available for smaller sizes. Any replacement bearing will also have to have threads added to it, but the flange is reusable.
     
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  15. speedwagon

    speedwagon Senior Member

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    What do you mean by removal screws? Are you saying when you need to remove the flange you run the screws in and use the heads for leverage to spin it off? Just found this thru hull nut at the consignment store might work for a flange. 20190613_165142.jpg
     
  16. Keelboater

    Keelboater Captain

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    3 jack screws that can be used to pull the bearing out of the tube after the set screws are removed. The jack screws contact the end of the tube when they are installed and tightened. Just like the one powder pro posted, but two pieces instead of one. You would need a flat surface that is thick enough to tap. I don't think that through hull nut would work for that, but it might. Once you get the bearing and flange assembly removed, you unthread the flange from the old bearing and thread it onto the new one.
     
  17. speedwagon

    speedwagon Senior Member

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    Thanks, that makes sense. Yeah, I doubt the nut will work.
     
  18. Toolate

    Toolate Captain

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    Are we going to get to the sawzalling soon or what?!?! :)
     
    Last edited: Jun 15, 2019
  19. speedwagon

    speedwagon Senior Member

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    20190609_151844.jpg

    The points of the 'jaw' will be cut off. I'm aligning now but unfortunately found out today the shaft was never parallel to the centerline about an inch off to starboard at the prop. I want to fix it now but will have to replace the engine mounts first as they are too crusty to adjust. Trying to figure out how to lift the engine to replace the mounts without heavy equipment. Thinking cribbing off the deck with a beam above and a chainfall. Only need to lift one end at a time.
     
  20. Keelboater

    Keelboater Captain

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    I used 4 x 4's and made a simple gantry for a chain fall. A friend donated a steel T beam that works..............

    IMG_3508.JPG

    IMG_3509.JPG
     
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