plywood/epoxy question

Discussion in 'Wooden Boat Building and Restoration' started by woodrat, Apr 20, 2009.

  1. woodrat
    Joined: May 2007
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    Location: Skamokawa, WA

    woodrat Junior Member

    So, about two years ago, I picked up this newly constructed and abandoned plywood hull for free. It was built from 24' hankins cuddy cabin plans. It is made of doug fir marine plywood, two layers thick, with no frames inside. the inside is dry and unfinished, and the hull is still upside down on the molds. When I got it, he had put down one layer of cloth on the outside and epoxied it. It had been partly covered, and partly exposed to weather

    I had hoped to get on it right away, but life intervened. It has been stored in my driveway, sometimes tarped and sometimes getting rained on, but upside down for these two years. I am getting ready to work on it this summer, and when I untarped it the other day, I saw that there are a few spots of black mold showing through the cloth. No spot on the plywood seem soft, and when I cut the cloth away from one spot where it wasn't well attached, I found that plywood didn't feel wet, but not bone dry either. There are also a lot of areas where the cloth didn't ever adhere.

    What I would like to do is finish the hull pretty simply, with a small cuddy cabin far forward and a big open deck for fishing and camping out of. I would have an aluminum offshore bracket put on it and an 150-200 fourstroke outboard. I haven't decided whether I want it to be self bailing, or with a removable grate or slatted floor with bilge pumps.

    So now I am trying to decide what the next course of action should be. I have built a couple of skin on frame kayaks, but I have virtually no experience with epoxy/plywood boats. Is this something that can be fixed and moved forward on? where would I start?

    What I'm imagining is that I need to peel this cloth, dry the hull out more and then give it a proper cloth and epoxy finish. Is there a way to fix this without peeling the whole thing back down?

    some pictures:

    http://www.redalderranch.com/pictures/hulldetail1.jpg
    http://www.redalderranch.com/pictures/hulldetail2.jpg
    http://www.redalderranch.com/pictures/transomdetail1.jpg
     
  2. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

  3. woodrat
    Joined: May 2007
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    Location: Skamokawa, WA

    woodrat Junior Member

    any reason not to just strip all that bad glass off, clean and dry the wood well and just paint it?

    Why all the fuss with the glass and epoxy? If I can't get the hull perfectly dry, won't the epoxy encapsulation just trap that remaining moisture in there and give me headaches for years?
     
  4. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    my 2 cents

    by the time that you have spent all the money on a huge motor -and -and -and -and

    and you have done all the work to build and fix



    my advise to you is burn what you got
    chop it up for firewood
    and start over clean and fresh

    and then buy the plan that you REALLY want

    really you are wasting your time on an old thing
    the hull is only a very small portion of the total costs

    i looked at all your pics
    and i dont like what i see AT ALL

    and remember start off small
    first build a dinghy and then your dream boat
    believe me i am at it everyday of my life
    been there and got the badge to prove it
    bought the "t" shirt :D
     
  5. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I disagree, the wood is wet, moldy and has a bad sheathing, but it's salvageable.

    No, you don't need to put on a new sheathing, but it does offer a lot of abrasion protection, plus water proofing. Plywood is particularly prone to these issues, especially the end grain, which is easily damaged and lets in moisture.

    Yep, the cloth has to come off. It looks like a fair portion will just peel right off, but other areas will require it be ground off with a big disk sander.

    Once the 'glass skin is removed, rig up a cover that doesn't touch the hull, but keeps the weather off it. Of course a shop would be best, but outside works if you keep it dry. Left to naturally dry out, it can take quite a while outside, especially in humid areas. Use a moisture meter to check the progress of the hull at several locations. You're shooting for 15% or less.

    Once it's dry, hit the whole hull with the big disk sander again to remove any traces of the old resin and more importantly provide "tooth" for the new coatings. The hull wouldn't be hurt if you used a 36 or 40 grit all over, though these grits can get you into trouble fast by removing way more stock then you want.

    After you've cleaned and roughed up the hull, you can make the decisions about epoxy/sheathing or paint.
     
  6. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    Bin it and start from scratch cheaper and quicker, and you will KNOW the quality of the wood and work. - - - The same rule applies to most "fixer-uppers" until you develop a high level of skill and knowledge from doing it often.... "If you gotta ask, don't do it"... why try to fix someone else's dream - it is their dream - let it die as such... and build your own dream - without the angst/pain/hassles/doubt/uncertainty of fixing someone else's fuckup.... - make a nice "newstart" fire...
     
  7. woodrat
    Joined: May 2007
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    Location: Skamokawa, WA

    woodrat Junior Member

    well, one reason to keep on with this one is if I can save it, I save 2 or three thousand dollars in materials and a whole lot of hours.

    I understand why I'm getting advice to junk it, and that is something I've considered, but what I'm looking for is a work boat, not a perfect shining beauty to take to wooden boat shows. The way this thing is built, if I can clean it up and save it, I will get many years of useful service out of it, and if the hull goes to pieces eventually, I will still have had many great days on it, and I can move the outboard and other parts to another boat.

    Even if it takes me many hours of sanding and grinding to get this hull clean again, it will still be faster and cheaper than starting from scratch on a new hull.
     
  8. Manie B
    Joined: Sep 2006
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    Location: Cape Town South Africa

    Manie B Senior Member

    I cant argue this point with PAR because he has a sh1tload more experience than me, i am a "hobby'est" homebuilder

    however one thing that i did recently is buy a 10x magnifier that watchmakers use - you simply wont believe how much more of the "black spots" there are under magnification - that is what scared me of - and lack of experience and simply not being sure.

    I fully agree that if you know what you are doing it is salvageable = experience.



    but you will have a very hard time convincing me of the following



    the little dory that i built i had a couple of problems and mistakes - and there i learnt that even fixing your own "problems" is a mission of note

    i simply wont work on "old" materials because when you start with fairing and painting to have a "reasonable" boat - (not a shiny piece of "furniture") you will soon realise that if you are 100% sure of your "foundation" you can carry on

    if in doubt - it eats like a cancer afterwards
    when you smack that first wave with your 150hp outboard you MUST have 100% confidence that the job was done right

    you dont know what short cuts the previous owner took,
    when you have worked your arse off on cleaning and sanding epoxy you dont want to "wonder" maybe yes maybe no

    a well built owner boat is a extremely fulfilling sight, from the first board that was cut, right up to finished product
    every step of the way no matter how small, is the adrenalin rush of - i did it right. :D
     
  9. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    For the money you have in it so far, including any sheathing stripping supplies, you couldn't buy the 15 to 20 sheets of plywood that make up a typical hull of that size, let alone build it.

    This is why it's worth keeping. This also assumes the construction was reasonable and no other major flaws or defects are seen.

    The bare hull, on a boat of that class, is less then 20% of the total build cost and effort, so you're not gaining as much as you think. Trim out and equipment will eat up the major portion of the budget.

    If it was me, I'd insure seams were well filleted and taped, maybe with over size fillets and healthy taping, just to make sure I'd covered any errors on the part of the previous owner.

    Some folks are "doers" others "don'ters". Be a doer and I wouldn't bother paying attention with the don'ters.
     
  10. ancient kayaker
    Joined: Aug 2006
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    Location: Alliston, Ontario, Canada

    ancient kayaker aka Terry Haines

    I have a concern Paul; if the glassing was such a lousy job who knows how bad the rest of the workmanship is? No frames, and who knows how well the 2 layers of ply are bonded?
     
  11. woodrat
    Joined: May 2007
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    Location: Skamokawa, WA

    woodrat Junior Member

    I think the glassing was more of an incomplete job than a lousy one. He just did the first layer and then stopped working on the boat, and it sat in the weather and delaminated, probably partly from sun and UV and partly from a not very well wetted out epoxy application. I could be wrong, but the construction looks pretty skookum other than the glass layer.

    Right now, I have exactly zero dollars into this, besides a dozen gallons or so of diesel that I burned hauling it home. So even if I have to put a bunch of extra work in and start over on the glass layer, I am still way ahead of what I would spend buying a bunch of plywood and starting over. Of course, having zero dollars into it also means that this would be the time to walk away, if that is the right answer in the end.

    I expect that I will need to spend $10-15k or so finishing it, depending on what I decide to do for power, but that is still an awful lot less than I would have to spend on a comparable craft on the used boat market, let alone new.
     
  12. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    To me it would seem the project languished for some years. Left without a protective coating on the sheathing the epoxy would break down fairly rapidly. This doesn't suggest the internal bonds are bad, just the sheathing, which fortunately will now come off fairly easily.

    It's possible it's a real piece of crap, but most who take on the bother of a double skin build, have the sense to try to do things right. This coupled with the fact the present owner has a few builds under his belt, further supports the bare hull has a good chance of completion. In other words, this isn't his first pony ride, though it is with this method, but he has a clue what to look for.

    Go for it Woodrat . . .
     
  13. oldsailor7
    Joined: May 2008
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    Location: Sydney Australia

    oldsailor7 Senior Member

    From your location in WA I am guessing that you are boating in fresh water. Douglas Fir and Fresh water are bad, bad news. Even rainwater in the bilge will rot Douglas Fir in the most alarming way and require constant painting in the bilge with green cuprinol to maintain it.

    Give it a "Viking Funeral". It's an ugly looking beast anyway. Why try to make a silk purse out of a pigs ear. :eek:
     
  14. McFarlane
    Joined: Apr 2009
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    Location: Australia

    McFarlane Macka

    Id be worried about sticking a 150 on a double skinned plywood boat unless you use it in smooth water, where I come from this thing would snap in two off the back of a wave with that much HP on the transom. If you want to save it par is right rip the glass off and dry out the plywood, make sure there is no soft ply and coat it with some evidure ( timber preserver ) the ply will absorb this and go nice and hard then glass it, maybe 2 layers of 10 oz cloth, nice and strong, hope the transom is nice and thick.
    Macka :D
     

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

    PAR Yacht Designer/Builder

    There is no correlation between double planked plywood hulls and being fragile, in fact the opposite is true.

    There's no reason to scrap the boat if the hull is basically sound, just a poorly done sheathing. You'll never be able to build a new hull with the effort it takes to strip a sheathing, let alone the money for new materials.

    Strip the sheathing and give it a good once over with a orbital and see what you have. You will not have lost much if it turns out to be a waist of energy and the reward could be a good basis for a fishing boat. Again, go for it . . .
     
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