Chainplate replacement - Rotten and water soaked Knees under my chainplates

Discussion in 'Sailboats' started by alaskanviking, Apr 30, 2012.

  1. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Log onto www.epoxyproducts.com and have a look at their underwater cure epoxies. If in doubt, talk to Paul (the owner and a forum member here) about a reasonable solution.
     
  2. Sir Rondo Norma
    Joined: Jun 2013
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    Sir Rondo Norma Junior Member

    Thanks Par, Just got off the phone with Paul and we've got a product on the way.

    Cheers!

    Ron
     
  3. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Yep, Paul knows his stuff - he's been at it for 20 years. Call him back up and tell him I sent you, he might give you a discount . . .
     
  4. thegui
    Joined: Jan 2016
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    thegui New Member

    At the risk of not getting an answer this thread is exactly what I was looking for. Now 3 yrs later I'm sure more older boats are falling into this category. I have a 84 Hunter Cutter that the water has invaded the chainplate knees. I have the same issue as Sir Rondo, trying to 'dig' out the rotten wood. If I repair the way you suggest and insert a piece of plywood to replace what was dug out I'm not sure how much of the fiberglass side of the knee to remove. And without seeing it I'm not sure what a tab is.
    Thanks
    Jim
     
  5. gonzo
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    gonzo Senior Member

    A tab is a strip of fiberglass that is laminated to the bulkhead and the hull. It makes an approximate right angle at the joint area. Usually there is a fillet of some kind to create a radius. It helps lay the fiberglass, and it spreads the force over a larger area.
     
  6. thegui
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    thegui New Member

    Thank you... I guess I can remove or cut out the fiberglass to get down to good wood then rebuild from there.

    Thanks
     
  7. PAR
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    PAR Yacht Designer/Builder

    Yep, that the usual course, grind back to good, solid laminate, dig out the bad stuff, then relaminate it all back together.
     
  8. thegui
    Joined: Jan 2016
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    thegui New Member

    Knee replacement

    An update to my previous thread...
    I'm still digging out rotten plywood. I like the original post have to remove the teak frame to get at the rest of the shelf. Its not a pleasant job and I have a few scrapper blades as this stuff just tears the teeth right off the blades. But I'm getting there . I will post pictures in the future.

    Jim
     
  9. thegui
    Joined: Jan 2016
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    thegui New Member

    knee replacement - Sailboat

    Here are some pictures of my project so far. IMG_20160206_115350.jpg

    IMG_20160206_115406.jpg

    IMG_20160206_145903.jpg
     
  10. JSL
    Joined: Nov 2012
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    JSL Senior Member

    On this topic, the latest issue of Professional BoatBuilder (# 156, Feb/March 2016) has an excellent article by Dylan Bailey on surveying in way of chainplates. And, he also addresses the matter of titanium vs SS for chainplates.
    A bit late for mr. Thegui but certainly applicable to any sailboat over 10 years old.
     
  11. Boomvang10
    Joined: May 2017
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    Location: Florida

    Boomvang10 New Member

    New to the forum first post. I have the exact same problem and have hollowed out the knee after cutting off the inboard edge. I am at the step of deciding what type of core for replacement. Will Coosa bluewater 26 work in place of plywood for this situation.the original material was Two 3/4" 7ply pieces sandwiched together creating a 1.5" core. Ive read other forums and that it had different physical properties and a novice shouldnt attempt to use foam type materials. I want to use coosa because it seems stronger and the fact i would not need to worry about sealing or creating epoxy bushings for where the bolts pass through the plywood(for chainplate installation) to limit water intrustion. G10 is out of my price range. My knees are 1.5' X 3' and i have 6 total. The material for coosa so far is 600$ G10 was $1500. I would like to use a composite core for strength and rot resistant properties. I have plenty pictures but am having trouble uploading them. I created an album with the pictures? Ill keep trying.
     
  12. Boomvang10
    Joined: May 2017
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    Location: Florida

    Boomvang10 New Member

    Here is one of the knees. 1.5' along the top and 3' along the hull.
     

    Attached Files:

  13. BobBill
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    Location: Minnesotan wakes up daily, in SE MN, a good start,

    BobBill Senior Member

    Here I am late and learning...thanks Par and Gonzo and all. For some reason, chain plates may be paranoid...always have...
     
  14. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    Also, the deck repair, if you cut from above, will be about 10 time wider than the thickness of the deck for a proper taper. You can't just fill in a small gap.
     

  15. Fred Roswold
    Joined: Mar 2005
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    Fred Roswold Junior Member

    One thing which hasn't been mentioned is the desirability of building your new chain plate system so that the chainplates themselves can be easily removed for inspection in the future. Water has a habit of seeping down from the deck and stainless can develop crevice corrosion or rust or cracking. The ability of pulling one apart without destroying the boat will be welcome some time down the road.
     
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