Chine work

Discussion in 'Fiberglass and Composite Boat Building' started by Aaron Darby, Feb 2, 2021.

  1. Aaron Darby
    Joined: Feb 2021
    Posts: 16
    Likes: 5, Points: 3
    Location: Virginia Beach

    Aaron Darby Junior Member

    The boat is a 64' Harkers Island. I've been told that they added the chine at a later date and that it is pine, and evidently that isn't good. Its in bad shape and while I would like to remove it and start over I don't have the time or permission from the boss (my friend who owns the boat). It has been grounded a couple of times and the pine has cracked, or checked quite a bit. The previous repairs have failed, not sure if faulty workmanship or just wear and tear. To be sure they didn't use heavy enough fiberglass if any to protect the chine.
    1. I have started to use an air grinder and ground out cracks as deep as I dared, attempting to get past the split, then coated with a couple coats of epoxy, and filled with fairing compound. I plan on using biaxial fiberglass to protect the chine, fair it and off to the races.
    2. There is a large section, about 10 foot long, about 1 inch deep and 2 inches high that was previously damaged. The previous repair was filled with fairing compound, maybe structural epoxy and it didn't take very well. I can peel it off in sections by hand and underneath isn't a clean cut, more like split wood, like somebody had ripped a 2x1 inch section, 10 foot long off the chine then filled it in with epoxy. My only guess at why it didn't take is that perhaps they didn't put a coat or two of epoxy in the damaged area before laying in mixed epoxy. In an attempt to try and make it a better repair this time I thought I might take a skill saw and cut a fresh section out and epoxy in a new 2x1 inch section of wood instead of filling in with a huge batch of mixed epoxy.
    iCloud Photo Sharing
  2. Will Gilmore
    Joined: Aug 2017
    Posts: 832
    Likes: 350, Points: 63
    Location: Littleton, nh

    Will Gilmore Senior Member

    What kind of pine? There are a number of pines under the heading Southern Yellow Pine and they are commonly used in marine applications, framing, stringers, planking and plywood. I don't know a whole lot about it, but I do know Clark Mills, of the Optimis Pram, the Windmill and the ComPac 16, built with it.

    -Will (Dragonfly)
  3. bajansailor
    Joined: Oct 2007
    Posts: 3,188
    Likes: 1,259, Points: 113, Legacy Rep: 37
    Location: Barbados

    bajansailor Marine Surveyor

    Re the fibreglass on the hull bottom, was this done with polyester or epoxy?

    Would it be feasible to clean up the chines on both sides, grind away everything that needs grinding, fill any cracks, dig out any areas of rot (and scarph in bits of new timber if large, otherwise fill with epoxy filler), and then laminate over the whole chine with cloth and epoxy?
    Will Gilmore likes this.
  4. fallguy
    Joined: Dec 2016
    Posts: 6,873
    Likes: 1,428, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Well, you are making a mistake. None of those holes are to be filled with fairing compounds. Fairing compound is simply too soft.

    Grind out all the rotten material 100%. No loose or wet or rotten material can remain or it will rot again.

    You need to put a temporary head flashing over the work area so no rain leaks down in. Bag under the head flashing. Butyl tape works pretty well for both.

    Grind and grind some more. Use an oscillating tool to hog out all the rotten stuff. The tool has to work much harder on good material, so it is easy to gauge your work.

    After grinding; you need to blow out all the dirt; then dry it out fully. This might require a day with a heat gun and some super careful heating or you can use halgogen lamps, but even those can catch fire one the moisture is all gone. You could try to use vacuum, but that requires a pump and the back cannot be holed.

    Once you have it all dry. Close it to the elements and wait a day and dry it again. With wood, it likes to surface dry and then given some time; it will rewet.

    After you are certain things are dry; make a milled fiber fumed silica and epoxy mix with about 50/50 milled fiber and silica. Slump test it. It needs to be pretty stiff. About 2-2.5 dry to one epoxy by volume is closish.

    Prewet the wood with epoxy resin a bit. (First)This will help prevent drysuck and bond failure.

    After you fill it all you can put a board with ship tape onto the area to keep it from sagging out. Hold it there with butyl tape or any means possible.

    sand it flat and refill the next day to flush allow to cure and sand again with 40-60 grit

    grind off all loose glass on the edges, paint with epoxy and lay wetted 1708 tapes over the area...consider using two tapes and stagger the edges for fairing

    consider a sacrificial timber if those areas are getting dock rash; you bond it to the hull with 5200 and a couple short screws and just use something like white oak or some local hardwood lumber

    epoxy is your friend here

    the classic boston whaler repair is to hog out the inside more than the face; this way the plug can never force its way out; consider this as a good strategy

    i gotta go build a boat!
    Will Gilmore and bajansailor like this.

  5. Aaron Darby
    Joined: Feb 2021
    Posts: 16
    Likes: 5, Points: 3
    Location: Virginia Beach

    Aaron Darby Junior Member

    Bajonsailor, I think it was epoxy but nobody knows for sure. And yes that’s the plan, grind and fill, cloth and fair. Looks like I’m making a few mistakes though

    fallguy, great advice thank you. I’ll switch filling compound, and work at getting the wood dry before working with epoxy. It makes sense that perhaps the previous repairs failed because they didn’t let the wood dry or remove all the rot. I hope to make better repairs and really appreciate all the advice you guys give.
    fallguy and bajansailor like this.
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.