Sheathing timber hull

Discussion in 'Wooden Boat Building and Restoration' started by Brands01, Feb 26, 2007.

  1. Brands01
    Joined: Nov 2006
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    Brands01 Senior Member

    Hello all,

    I'll apologise in advance, because I'm sure this topic has been covered plenty of times in this forum.

    I may be taking possession of a 1950s timber sloop. She doesn't have any rot, but has got a few broken ribs - hence the owner is likely to give her away because he doesn't have the time or means to make the repairs.

    My plan is to let her dry out, remove the caulking and replace with thickened epoxy, sheath the exterior, and encapsulate the interior with epoxy to prevent the timber swelling and install laminated sister ribs.

    Is this the correct way to go about sheathing a timber boat?
     
  2. ncarter
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    ncarter Junior Member

    I would not cover the outside of the hull. Once water finds its way in (and it will, eventually)..it will rot the hull. Sister or redo the frames and recaulk. If you want a traditional boat do it that way. If you do`nt want any seams, buy an FRP boat.
     
  3. sal's Dad
    Joined: Apr 2005
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    sal's Dad Atkin/Bolger fan

    Get detailed information on the hull, including photos of problem areas. Take inventory of your skills and experience, financial resources, and available tradesmen/yards.

    Then ask your question again, here, and on the Wooden Boat forum http://www.woodenboatvb.com/

    There has been extensive discussion of this kind of project; my impression is that it may be appropriate to get a few more years out of a hull that is otherwise garbage. I have never heard of trying to encapsulate the interior - it would seem to me impossible to seal it well enough to be worth all that effort.

    Have you read Vaitses' book on the subject? http://tinyurl.com/2rwmnu

    Sal's Dad
     
  4. Roly
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    Roly Senior Member

    Faulty logic.The boat was originally designed to "move" with uptake of water.
    The design you have in mind is rigid.
    Saying that, you can re-engineer it, spend huge amounts of time and resources & achieve a good result.
    You are better off building a new boat to design than re-engineering a tired
    veteran;Unless that what does it for you.

    My project:http://www.imagestation.com/album/index.html?id=2120245606
     
  5. Pete Dennison
    Joined: Dec 2006
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    Location: Sale Australia

    Pete Dennison Pete D

    Hi Brands! Just finished completely recaulking a 50' ex-trawler. It is now tight as a drum and has taken up beautifully. My boat is 60 years old and has worked nearly every day of its life but after a lot of work and really not that much cost I have a functional as/designed hull again. A lot of the ribs have been sistered and that was time consuming but relatively easy. I engaged the services of professionals to recaulk and total cost was only $4000. (I did all the puttying though!!) Costs are probably higher in Syd than here in country Vic but I reckon your "sheathing" proposal would be more expensive and probably wouldn't work. My advice - contact the professionals to give you a re-caulk quote and get them to do one rib for you while you watch! Good luck!! Pete.
     
  6. PAR
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    PAR Yacht Designer/Builder

    It would be much cheaper and easier to recaulk and repair the few frames, then to skin her after filling the seams with plastic.

    As a rule sheathing the hull is a death nail to much, if not all of the underwater structures. These boats need water to perform their function. You can use a heavy fabric skin, which can provide several years of additional service to an other wise spent hull. A light weight skin will do very little other then provide abrasion resistance. Filling the seams with hard plastic will destroy the planking (if they don't spit it out the first chance they get), though wedging the seams is an option, but also has it's issues.
     
  7. Brands01
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    Brands01 Senior Member

    Thanks everyone for your replies and advice. At first, I just thought I'd posted on the wrong part of the site, and that the negative responses were a result of disapproving anti-glass wood purists.

    However, the fact that everybody has replied and suggested my idea is flawed would tend to indicate that I am well and truly in the wrong :eek: :) .... apart from the fact that I am a complete amatuer, and most people here have years of practical experience to draw from.

    However, not wanting to just take 'no' for an answer, I would like to pose this thought for your collective feedback (and this may highlight my ignorance, but please bear with me):

    My understanding is that the sheathing approach usually fails due to the timber continuing to expand and contract when adhered to a fixed body - the glass sheathing - which causes spliting planks and the like. The timber expands and contracts when the moisture level goes up and down. If each plank is completely encapsulated in epoxy (inside, sides/seams, and outside), the moisture content of each plank cannot change, therefore there will be a negligible amount of expansion and contraction, equalling success.

    It seems to me that it is fairly common to sheath timber boats in glass (at least here in Australia) to protect from the likes of worm etc, hence my persistence. Surely they can't all have it wrong?
     
  8. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    OK, here is my opinion :)

    It's better to do it on new boats than on old ones.
    Epoxy will stick better to untreated wood than to any kind of oil, varnish, paint etc. In old boats it's better to use a penetrating mixture if turp(?), tar and linseed oil or similar.

    In a new boat you can sheat both sides before you install frames, bulkheads and other internal structure. Then the skin will also be thinner, so that the two layers of glass is strong enough to stabilise the wood.

    If you sand the outside of the hull to bare wood and remove any appendages (keel?) you may be able to make a watertight outer skin, and it will probably stick to the wood, but what about the inside? Are you planning to strip the boat for all interior structure and the rebuild it?

    I think I agree with the others.
    It's a lot of work, and the result is probably a shorter life for the boat.
     
  9. Brands01
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    Brands01 Senior Member

    OK, I am convinced. You guys are the experts. I'm alot more comfortable with epoxy and glass, but probably only because I've worked with them. I shouldn't let this get in the way of me learning about the joys of timber boats - I love boats - why not expand my knowledge to include timber boats as well as glass ones?

    Time to do some detailed research on this boat to see if I'm up to the task!

    Thanks again everyone for your advice - you've probably saved me from making an expensive mistake!
     
  10. Raggi_Thor
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    Raggi_Thor Nav.arch/Designer/Builder

    I am no expert in this area, but I used to "fix" an old wooden boat with epoxy and small pieces of wood and glass and whatever. When I sold it, the new owners removed all my "fixes" and repaired properly, cut out damaged wood and replaced with new pieces of similar wood, fastened with copper screws and bolts. I don't think the "right" way is as hard as we think.
     
  11. SamSam
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    SamSam Senior Member

    Vaitses book that sal's Dad mentioned is pretty positive on the results. He had boats he had done 15 years before with no apparent problems. The book was published in 1981 so if any could be found now, it could be seen how well his way works.
    His way involves little or no preporation of the hull other than to smooth lumps and bumps. On boats up to 50', a layer of 1 1/2oz mat and 18oz woven roven was applied with polyester resin and then, while the glass was still in the green stage, heavy duty galvanised air gun staples were applied every few inches. After that set, more layers were applied until the finished thickness was achieved, 1/8 to 1/2". The main thing was the glass was mechanically fastened to the wood and didn't rely on resin adhesion. As far as weight, most hulls eventually floated higher than originally, once all the water dried out of the wood hull.

    They have been doing a variation on Vaitses way on wood shrimp boats here for almost 20 years. They get 5200 in 5 gallon pails and trowel on a layer and then imbed woven roven into it. Once the 5200 is set enough, the WR is saturated with poly resin and also a layer of mat, once that is set but still in the green stage, the staples are applied and then it's built up to the desired thickness.

    Of course, if a real smooth finished look is wanted, the usual massive amount of handwork will have to be undertaken.
    Sam
     
  12. Pete Dennison
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    Pete Dennison Pete D

    Hey Brands! I was the same as you, only ever had glass boats until I bought this trawler. Have read lots, watched lots and now love working on the old girl. Like the Harbour Bridge - I'll never be finished but it's fun getting to the end and starting all over again!! Would be happy to forward some pics of the before and afters if you're interested and if you are ever down in Gippsland call into the Port of Sale and have a look. Regards Pete D (dennop@hotmail.com)
     
  13. PAR
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    PAR Yacht Designer/Builder

    The plastics used to sheath hulls are polyester, vinylester and epoxy, in that order of preference and stick-em ability. Polyester shouldn't even be considered, except to bring a few more seasons back to a well spent old hull, that would be dead without it. Polyester doesn't stick worth a damn to fresh, new wood, let alone old, dirty, oily, water soaked wood. Even if you left the boat in the high desert for a year, she'd probably have areas that have too high a moisture content to get any plastic goo to stick reliably.

    Many people will tell you polyester will work, but I've been restoring boats of every shape and size for over 3 decades now and the stuff doesn't work. The only success stories are hulls that have such a thick skin of poly on them, they in fact have two hulls, one plastic and the other wood. These are plastic boats with a slowly rotting wooden structure inside them.

    The manufactures, insurance companies, reputable builders and restorers are pretty much in agreement on this. Staples, exposed nail heads and all sorts of crazy things have been tried to improve the ability of polyester to stick to old wooden hulls, but the bottom line is it doesn't. Why would the manufactures switch to more costly vinylester if polyester would work well enough?

    There are only a few good ways to seal wood and all require embalming the individual pieces. This is reasonably easy in new construction as the parts go in the structure, but very difficult in repair or restoration, where the pieces may remain partly or wholly in the boat. Unless the wood is entombed in the sealer of choice (lets face it, epoxy is the ticket) you have little more then an expensive paint job of goo, smeared on the pieces. The wood will swell and the coating gets shrugged off in time, regardless of the wild statements of some, that will have you think there is a miracle goop in a can available to solve you dilemma.

    Some wooden structures require a plastic coating, but traditional structures, likely as you have, don't live well with them. Properly repaired, the boat will last another half a century, possibly longer with newer techniques and adhesives and its value will increase. The moment you mention a 'glassed the hull, most prospective buyers will walk away and rest assured the value will drop considerably. This is a very clear indication of the worth, placed in 'glassing a wooden hull.

    Much has been written on this subject here and elsewhere. Use the search function on this site and have a look. Much lab testing and the trials of time and mother nature have brought the jury in on this issue long ago.

    For what it's worth, in 1981 (when the above mentioned book was written) the jury was still out in many folks minds. A quarter of a century later, the verdict is in. I've peeled the poly skins off of plenty of boats to understand the material's abilities.
     
  14. Brands01
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    Brands01 Senior Member

    OK, so there are varying opinions - as always when it comes to boats. I think I'm convinced that the non-sheathed route is the way to go.

    What about protection from worm? How is this acheived in timber boats these days?
     

  15. Poida
    Joined: Apr 2006
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    Poida Senior Member

    Brands01, mind if I hijack your thread here for a minute mate?

    Par, got me worried there for a sec you mentioned a list of sealers in list of preference and had epoxy last. But you qualified your preferences later that put epoxy 1st.

    Mind if I ask you a question?

    When you glue components together can you soak the parts in sealer first or does that reduce the glue's stickability. (You probably won't find that word in the English dictionary)

    So, for example, making frames. Do seal the frame components first in sealer before you glue them or glue the components together to bare wood and then seal the frame later. If this is the case you would have to leave the rebates for the stringers unsaeled.

    Or, doesn't it matter?

    I was thinking that because the sealer I have access to recommends that you thin the sealer down to 50% for the first coat it may soak in better than the glue will, thus allowing the glue to just stick to the sealer, but I am often wrong. (You've already read some of my past posts so you already know that)

    Can you please advise?

    Thanks in advance.

    There ya go Brands I've finished, you can have yer post back. Cheers
     
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