Epoxy in wood plank construction

Discussion in 'Materials' started by nickninevah, Apr 26, 2012.

  1. nickninevah
    Joined: Apr 2012
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    Location: Seattle

    nickninevah New Member

    Hi all,

    Maintenance / restoration question. I'm helping restor a 1928 wooden hull schooner. She is built with the old wooden hull plank method. And the maintenance is a nightmare. Not just the hull, but also all the joiner work inside the boat, the wooden masts, etc.

    Now I know that these boats were meant for the wood to stay moist and swell. But I've often wondered about coating / infusing the wood with epoxy to cut down on maintenance.

    Anyone have any experience with this? Is it helpful or just a bad idea? Can we do it for the mast? For the hull planks? For the frames? What about the joiner work? And would it need to completely saturate the wood, or can we get by with just a top coat? Thoughts everyone?
     
  2. Landlubber
    Joined: Jun 2007
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    Location: Brisbane

    Landlubber Senior Member

    "And would it need to completely saturate the wood, or can we get by with just a top coat?"...you will only ever get a top coat anyhow, wood is made up of closed cells, so you can get to only a few of the top layers when you "saturate"......I discussed this with PAR some years ago about thinning epoxy to help "saturate", and he well explained that it is simply not going to happen, all you do is get a poor epoxy finish that has been compromised by altering the design parameters of the two part mix, so, do not expect stauration whatever you do. There is a very knowledgable resin supplier not far from where I work here and he and I discussed this extensively one afternoon, same opinion in the end as PAR started out saying, epoxy mixed as it says on the can will give the best strength and waterproofness that it is capable of supplying.
    Wooden boats require more work to maintain than plastic boats, such is life.
     
  3. gonzo
    Joined: Aug 2002
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    Location: Milwaukee, WI

    gonzo Senior Member

    It is a sure way to ruin a boat. To start with it has decades of oil and solvents that pretty much saturate the surface of the wood. If you are thinking of turning it into a monocoque structure, it is not realistic. Maintenance should not be a nightmare. Usually the problem is years of well intended "improvements" that only cause damage.
     

  4. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    There's quite a few locations on an old wooden boat where you can employ epoxy, but an old carvel hull shouldn't be epoxied. The edges of these planks have to swell for two reasons: the first is the obvious need to seal the seam and keep your socks dry, but the less understood need is to help provide a mechanical edge set along each caulked seam. When the seams have good caulk and are swelled closed, the hull becomes a homogeneous whole, essentially a single skin off wood.

    If the planks are epoxied, they'll still swell, just not nearly as fast (read it'll leak a lot 'til it does swell), but more importantly, the moisture will have routes into the wood, but limited paths out. This is the usual recipe for rot.

    As to furnishing, masts, etc., each will have to be separately accessed, as some also need to "move", while others not so much. As a rule, traditionally built wooden boats are an assembly of pieces, all sharing loads with neighboring structural elements. As a load is applied, the structural elements in the area, begin to absorb the strains and also moving a bit, transferring some of these strains to other, nearby structural elements. This is why you see lots of little dainty frames, stringers, etc., instead of huge hunks of timber. The movement between these separate pieces is usually key. It's what keeps one element from absorbing enough load to snap. If the interconnections between these separate elements are frozen with epoxy, then the movement stops and load sharing stops with it. Now, a localized strain will impart all of it's force on just a few structural elements and you'll get lots of broken boat bits.

    The best way to keep a boat of that vintage is to preform the repairs (traditionally) necessary, in a timely manner and observe a strict maintenance schedule. Don't wait until you pop a butt block, replace the things. Are the garboards half a century old, replace them, etc. Planking is a "consumable" item on an old wooden boat, just like an oil filter. It has a life span and when it's up, it's up. Sometimes you can stretch this a bit, but if the yacht is seeing regular use, then the best course is to have a "level playing field" in regard to certain things and planking is an obvious one. There's nothing more secure a feeling then the first cruise after wholesale planking replacement. After nearly a century, it's time, if this is you situation. The very best thing for a yacht of this era is, a loving owner with more cash then sense. Personally owning a few over 50 year old yachts myself, I can assure you if we had any sense about us at all . . .
     
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