Chainplate options for a refit

Discussion in 'Sailboats' started by Moird, Jun 11, 2020.

  1. Moird
    Joined: Jun 2020
    Posts: 3
    Likes: 0, Points: 1
    Location: Seattle, WA

    Moird New Member

    Hello,

    I am doing a refit of an old and neglected O'Day 27. It is this saildata: https://sailboatdata.com/sailboat/oday-27
    Well maybe more of a restore. The chain plates need to be replaced. The ones for the upper shrouds are a metal bar that went through the deck and connected to the main bulkheads. These of course leaked enough water over long enough period to rot the bulkheads out and the plan is to replace the bulkheads in this endeavor. The lower shrouds though were mounted on a plate in a form of a T that only is in the deck. They were completely encapsulated in glass with the only way to get them out was to cut them out and an area around them. Which while I was cutting them out water was dripping out of them. There is no hull reinforcement where the lower shrouds are. So I have been weighing out options to redo how these chain plates are done and have some questions about the different options.

    I could redo them essentially the way they were originally done and source out replacement parts and do exactly how they were done. This doesn't seem like a generally good idea for various reasons. Including crevice corrosion, the lack of being able to inspect/replace in the future without having to cut large holes in the deck.

    I have been looking into moving all of the chain plates to the outside of the hull. That seems like it has a few potential issues as well. Which from my understanding would require reinforcing the hull quite a bit. Possibly even adding knees at the chain plates. It will also require increasing the length of the spreaders as well. A downside it seems though is that this opens up a new area for leaks but now in the hull itself.

    Another option is to build knees on the hull and attach the chain plates to them, still moving them outboard but would not have the thru hull leak problem. Would still leak eventually around the chain plates through the deck as well. Not sure if it would be a better position or not than they currently in.

    Yet another option that I was looking at was building composite chain plates out of fiberglass along the lines of Composite chainplates: The ideal solution for composite hulls http://www.marine.marsh-design.com/content/composite-chainplates-ideal-solution-composite-hulls Which seems like it solves a few different issues all in hand, but has a problem that I can't layer it into the hull as the hull is already laid up. Could do the option with the bulkhead but there isn't a bulkhead for the lower shroud chain plates so they still end up in the same issue unless I spread it in the location over very large sections of the cabin top. Or move it to the hull side as well and run the glass all the way down the boat. It would still need to reinforce the interior of the hull as it wouldn't be strong enough for the change in loading.

    So I guess I am trying to figure out if those are the best options if there is another alternative or if I should just replace with what was there and not worry about it.
     

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  2. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    I have redone a deck on the same boat. The plate goes under the lower skin on the deck. It has the core and the two laminates to pull from. As long as the bedding/caulk is OK, there is no problem. Even if water goes in, it will take another 40 years to go bad.
     
  3. Moird
    Joined: Jun 2020
    Posts: 3
    Likes: 0, Points: 1
    Location: Seattle, WA

    Moird New Member

    Thanks that is helpful.

    I was under the impression that if water just sits on the chain plate that it could cause crevice corrosion and that they should be inspected every roughly 10 years for that.
     
  4. gonzo
    Joined: Aug 2002
    Posts: 14,277
    Likes: 586, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    Do you see any crevice corrosion?
     

  5. Moird
    Joined: Jun 2020
    Posts: 3
    Likes: 0, Points: 1
    Location: Seattle, WA

    Moird New Member

    I am fairly sure that there has been, but I will have to double check.
     
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