Re-glueing wooden mast

Discussion in 'Wooden Boat Building and Restoration' started by Aurora, Apr 15, 2005.

  1. Aurora
    Joined: Apr 2005
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    Aurora Junior Member

    Hello wooden boat builders,
    My square box construction mast is in need of repair. I was going to use wood glue to repair it but a friend said to use epoxy. I'm not sure how to do this and I was wondered if anyone could guide me through the process.
    Thanks,
    Paul
     
  2. yokebutt
    Joined: Aug 2004
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    yokebutt Boatbuilder

    Are you taking the mast apart or are you going to try to inject adhesive into open gaps? Proper surface preparation is imperative regardless of type of adhesive, epoxy would be my choice, especially if there are any gaps to span.

    As for epoxies, just about any of the common marine brands should work, like Gougeons' WEST system, System Three, Epiglass, MAS, etc, as far as wich one is the best, ask three different boatbuilders and you'll get four different opinions. Whatever brand you choose, get the metered pump-kit, as long as you meter and mix it carefully (scrape sides and bottom of mixing-cup, mix 'til you can't see any streaks and then some) and don't contaminate it with moisture or anything else, it will cure.

    Happy spooging,

    Yokebutt.
     
  3. PAR
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    PAR Yacht Designer/Builder

    Yokebutt, has a good point. It depends on how you plan to proceed, full disassembly (can be difficult without further damage) scarfed in repairs to affected areas or closing up some seams that may have broken open (you have to ask yourself about the remaining seams if some are starting to open)

    The yellow wood glue the hardware store sells is water resistant (some more then others) and can break down in a moisture rich environment. There are several glues available, each having good and bad points to them. What is the nature of the repair(s)? Plan of attack (disassembly, Dutchman, etc.)? Intended use (near shore, fresh water, salt, moored, trailered, etc.)?
     
  4. yokebutt
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    yokebutt Boatbuilder

    PAR expresses his rather similar (to mine) sentiments far more eloquently than I ever could, I think I'd better stop submitting my (relatively) inane missives presently.
     
  5. Aurora
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    Aurora Junior Member

    Hello again, Thanks for the info. One whole side of the mast section has come off and other sections just need re-glueing. Do I need to add filler to the epoxy when I mix it, and how many clamps and how far apart?
    Thanks again,
    Paul
     
  6. cyclops
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    cyclops Senior Member

    Wonderfull. Now you have complete access to do the job structurally and visually right, once. All those in favor of 80 grit sanding of inside box surfaces? Then precut to length and width strips of glass cloth which overlap the 2 existing corners by 2", and each other by 2". Slip the loose piece of mast in far enough to allow C clamps to be used to align the 3 sides FIRST. DO NOT GET careless with glue where the 4th loose piece slides part way in to allow the use of C clamps . If you are not SURE about where your gluing ends. Take a roll of heavy duty Saran Wrap and use it to cover the inside edges so you DO NOT accidently glue all 4 at the same time.------------------------I would only use full strength epoxy for all the joints. The mast came apart because of all the strains it has to handle. Last step is to coat the 4th piece sides and the mating sides of the mast, slide it just flush, C clamp. REMOVE ALL excess outside seam glue with a very thin flexable piece of plastic which folds down to the shape of the mast. Slide it along the seam, non- stop, end to end. If the 4th piece is not seated right, reset it now. --------------------------If you are not sure you can slide in the glue coated piece flush with the edges before the glue starts to set up. DO NOT do this repair. A 20' mast needs 2 people to not have a miss-aligned section. I can do it by myself with slow 1/2 hour epoxy.----------To stop a problem before it starts. The 4th piece is to be slid into the mast ONLY in a horizontal motion. OR gravity could ruin your best effort. Do NOT squeeze all the epoxy out.
     
  7. Aurora
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    Aurora Junior Member

    Hello again, Thanks for the advice. The mast is 32' long and if I use the "west system" how long is the working time of the slower epoxy? So, if I sand with 80 grit and overlap epoxy soaked cloth on the existing corners will the epoxy alone on the 4th side be enough to hold it structurally? Do you think that cable ties could be used instead of C clamps?
    Thanks,
    Paul
     
  8. cyclops
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    cyclops Senior Member

    Was the mast originally simple glued together? If so, epoxy simple glue should be at least as good. We are repairing not redesigning? You could use rope tourniquets every 5' to 10' with a 2x4 in each to hold pressure as needed.
     
  9. yokebutt
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    yokebutt Boatbuilder

    Aurora, I'd be a little leery of using zip-ties for clamping, I haven't had a lot of luck with them in the past, perhaps the heavy-duty type with a shallow wedge driven in under it might work, in any case, if you do decide to try, space them closely, like every foot or two, and make several passes tightening the wedges.

    When doing any critical bonding operation there are a couple of things to keep in mind. On a porous substrate like wood, you want to coat the mating surfaces with neat resin first, before adding the thickened epoxy, (WEST 404 should do) the thickened epoxy should be applied either as a thick bead on the center-line of the joint, or as a continous pyramid shape with the point in the middle of the joint. The idea is to get the adhesive to push all the air out of the joint without trapping it. By the same token, once you've started clamping, don't flex the joint in and out, epoxy will squeeze out and air will suck back into the joint.

    As for working time with 105/206,(if you're uncertain, use the 207 extra slow, just be sure to put the stick out in the sun for a few hours after it sets) it should be adequate, just don't leave large quantities of it sitting around in a cup, spread it out as soon as it's mixed. Many hardware stores sell empty caulking-gun cartridges, they're great for putting on thickened adhesive quickly.

    Happy spooging,

    Yokebutt.
     
  10. cyclops
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    cyclops Senior Member

    I am going to reccomend you NOT to use the wrap around tension methods. They can and do pull the beams in too far on some jobs. On a 32' mast that could really leave you with places of low spots. Panic sets in quickly in the mad scramble to try to push outward a low spot. After you get the 3 sides together, do a dry fitting of the 4th side in it's place. You may find it no longer wants to fit flush for the full length. If that is the case you will have to cut small pieces of inner spacer blocks wood to hold the 4th piece flush for the full length. Again , keep the 4th piece horizontial. You may have to use C clamps and the rope tourniquets and strips or blocks of wood under them to pull the high spots level. DO NOT GLUE the 4th piece till you can install IT perfectly 2 or 3 times. You are probably going to get 1 good CLEAN shot putting it in. BE absolutly sure you can lay it in FLUSH and HOLD it that way while it sets up. Rent enough C clamps to allow you to position it very confidently. This can become a disaster if you do not DRY FIT ALL the parts each time , before you glue them. MASTER the dry fits BEFORE you mix glue.
     
  11. gonzo
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    gonzo Senior Member

    To fill gaps Gorilla Glue works very well. It expands as it cures.
     
  12. yokebutt
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    yokebutt Boatbuilder

    Never knew a man who had too much money or too many clamps.

    Yokebutt.
     
  13. PAR
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    PAR Yacht Designer/Builder

    Aurora, I'd not use epoxy to fix this stick. I'd use plastic resin or better yet, resorcinol if it will be painted (purple glue lines with resorcinol aren't that pretty varnished) Plastic resin isn't completely water proof, but will serve if the mast is well kept.

    You don't seem terribly familiar with epoxy and the techniques necessary to have a successful outcome.

    Epoxy has the advantage of not requiring a lot of clamping pressure, but I see this as it's only one.

    Epoxy is not hard work, but does requires some experience to insure the goo will keep the staves of the mast tight. It's rather unlikely the mast was built with epoxy which could cause some differences in joint hardness between differing adhesives, which may lead to unfair bending in the stick under load or rig tensions not being the same at the shrouds or stays. Another issue I have a problem with, would be the material used is usually a light weight wood like Sitka, which means, unless you are quite religious about epoxying procedures, sanding the much harder epoxy off the seams will also remove a lot of the wood. Epoxy (even West 205) will not provide screw up time if things go bad during the gluing process. This usually creates a mad rush to get things done (before the epoxy kicks off in the mixing pot) this mentality can and typically does lead to mistakes being made. Epoxying up a 32' pole is a tough project for the inexperienced epoxy user.

    It's probable that a professionally built mast was glued up with plastic resin. Look at the remains of the glue, brown is plastic, purple is resorcinol.

    The trick to gluing up a stick is to work flat, dead flat, flatter then a 7 year old girl's chest. This usually means to work with the mainsail track side facing down on the table or horses you'll be setting up for this job. Did I mention working flat? Some use a string (I don't, it isn't truly flat across that length) some a bubble level (not accurate enough) or a cheap laser level (check the spec's, they can be off by a lot in 50') I built a table to build bird's mouth masts and used a very expensive surveyor's laser to flatten it up. The next trick it to work square (insure the mast isn't bent to one side). A taunt string will work for this, because the belly of the string will be down and not an issue.

    All this means is you'll be shimming up sections of the table or horses to keep them flat and rigging up a taunt string on top of this, a little off the surface to insure it stays in column.

    Basically it's all about setup. You have to provide clamping pressure to the parts, which must be held straight in both fore/aft and side to side dimensions. I do this with wooden blocks I screw down to the table during setup. These blocks are used as "dogs" where I insert wedges (between the mast and the wooden block) to apply force between the sides and also the table top.

    Don't be tempted to install any 'glass inside or outside of this stick. It will not stay stuck for very long and unless it's for gaff jaw chafe (leather is a more traditional approach for chafe, but 'glass will work) it will ruin the temper of the mast, will quickly stress crack or sheer off in spots, which will let in moisture and you know what that will do. You see, the 'glass will flex at one rate and the wood another (different rates of course) and they will separate in short order. If you want the epoxy and glass route to work, it must be completely dissembled, each piece completely coated (including fastener holes) with epoxy, then reassembled, using thickened epoxy. This will add a good bit of weight, expense and effort to the project.

    Cyclops does make a good point in that you should find out why this joint failed. Age can make adhesives brittle, including epoxy. If this is the case, you may well consider a restoration of the masts glue lines. It would be a nasty thing to do all this work, just to have to do the remaining, untouched seams next season. I don't mix any goo until I've done several dry runs and am quite comfortable with how it's going to be accomplished, have all clamps, tools etc. at hand and have alignment marks on the perfect fitting pieces.

    Log on to www.westsystem.com to learn about epoxy, encapsulation (the only way epoxy truly works with wooden structures) and the methods and techniques you'll need be accustomed to if you use this product.
     
  14. yokebutt
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    yokebutt Boatbuilder

    Mr. PAR, please forgive my ignorance, but what is this "plastic resin" you speaketh of?

    Yokebutt.
     

  15. cyclops
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    cyclops Senior Member

    I did not mention one simple fact that PAR touched on. There is no way we are going to make the re-glue job be as strong as the first gluing. the pores of the wood do have glue that was soaked into it during the first gluing. You are not going to be able to change that without new wood. Do your best shot and get lucky.---------------------------------------------------One thought why some old masts seem to last forever? It is always kept well sealed. With a new coat or 2 of varnish every year. ALL bang and dents which crush the finish and the moisture seal will let the wood swell a great deal there and start fractures long before wood rot appears. This sealing requirement extends to being able to seal the ends. I know that is not in the owners manual. Still, some masts are sealed that well, and do live long lives more easily than others of same wood and similar construction.
     
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