epoxy and glass inside and outside? and more

Discussion in 'Wooden Boat Building and Restoration' started by Nordson1960, Mar 23, 2005.

  1. Nordson1960
    Joined: Mar 2005
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    Location: Netherlands

    Nordson1960 Junior Member

    My wooden boat has a bad bottom (underwater)which has been glassed with 200 glass. They only covered the underwater part and left the rest blank. The top side of the hull is in very good condition but I calculate it to be only 0,5-1 cm thick wood. The hull apprears to be made out of big sheats of ply

    I would like to cover the inside of the hull also with glass and epoxy just to be sure the boat is strong enough for big lake conditions. The boat is very dry it has been drying for 6 months now.

    Furthermore also the keel is in bad shape. The former owner has covered it with epoxy and glass . Is it a good idea to create a new stringer on top of the keel and epoxy glu it to the crossmembers so that the boat gets more stiff and stronger.

    The boat has run a 40 hp outboard according to the former owner but as it turns out he has been making up stories so I dont know if the transom is strong enough. for a 40hp outboard.

    What kind of thickness should the transom have and

    Should i also reinforce it with a metal plate on the outside?

    Should I make new stringers and epoxy and glass them to the bottom and the first crossmember

    At this time the thickness is about 2 inches at the motor mounting place and the rest is about 1 inch. It is supported by 5 wooden stringers (very small) app 2 inches thick and in the shape of an L and app 15 inch long both ends. These stringers are bolted and glued to the floor of the boat (hich isnt very strong as I mentioned before)

    Sorry for my crappy English but I dont know the correct names for most parts in English I hope it is clear enough
  2. bjl_sailor
    Joined: May 2004
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    Location: MASS

    bjl_sailor Junior Member

    In addition to stringers that you might want to add you can also make epoxy fillets around the existing ones. If applied over dry, clean wood surfaces these will greatly reinforce the existing structure and also make laying any fiberglass cloth over them easier and more effective. The radius will allow the glass to lay better and provides strength on it's own. I'd suggest you start by rolling on a layer of epoxy over the entire bilge and hull filleting the existing framework and then adding addtional wood members as needed and then finally glass laminations.
  3. Umbra
    Joined: Mar 2005
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    Location: Deltaville, Virginia, USA

    Umbra Junior Member

    Nordson 1960
    I would like to offer an opinion here.
    It has long been My experience that encapsulating a rotton piece of wood will accelerate the decay process, because the wood cannot breathe.

    I have always been a strong proponant of W.E.S.T. System, and a firm believer in cold mold processes, and the various uses of glass reinforcing methods for additional strength.
    However, i would not cover a bad piece of material with a laminate without fully expecting it to fall into further, and accelerated decay.

    If it is possible to remove the patch, and scarf in fresh material a couple of inches past any suspect damage, then epoxy bond a laminate of wood over that, simply layered with weights or stapled or nailed onto the existing backbone could add enough strength to that member for it not to be a bone of contention in that structural area.
    Laminating wood is easy, rewarding and visually appealing. It is a great way to marry some strength into the backbone.

    I would then inspect the skin of the plywood, using the tried and true techniqe of "sounding" the ply.
    Good wood will resonate. Try it on a piece of ply at the lumberyard first to get a "feel" for the way it sounds, if necessary.
    A rotten piece of material will sound dull and lifeless, in comparison.
    A quick poke with an awl will tell the rest of the tale in any suspect areas.
    It helps to remain aware of any odor of rotton wood as an indicator, as well.
    The problem with plywood, is it sometimes has one or two inner cores going bad, but still surrounded with good material on each side, and that can make things difficult to ascertain visually.
    Replace any rotted wood found in the skin.
    I like bjl's answer with the additional stringers, and think the reply is experienced and obviously has been practically applied, fillets, radiuses and all.
    The only difference really is whether to encapsulate the suspect skin.
    I would, if i felt it necessary, add any additional (glass) material to the outside of the hull, instead.
    I would apply a generous amount of rock salt in the interior, rather than glass that over, to kill any re-moistened remaining rot spores, on a regular basis( Salt to taste).
    Addressing the transom.
    Take the boat by the stern and give it everything You've got, pushing and pulling.
    A fourty horse motor will do that and more.
    See if there is any give, flex, loosening, or squeaking when You are doing this.
    Try to basically rip the thing from the boat with the boat itself as the counterweight.
    Feel strong?
    If there is something iffy, reinforce it untill You are satisfied that it can take everything You can throw at it short of a pry bar. If it comes loose, better here on land than in the water.
    Two inches should be sufficient, if it is well attatched and not damaged. Check the attatched joint of the transom, sound for rot, and replace any damaged knees and ribs.

    A season at the lake sounds like a great reward. Have fun.
    Last edited: Mar 24, 2005
  4. Armada
    Joined: Mar 2005
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    Location: Turkey

    Armada Junior Member

    Hi, what would be your opinion for encapsulation of plywood both inside and out while building a new boat. Will that still have a breathing problem, if so what should I do ?
  5. Umbra
    Joined: Mar 2005
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    Location: Deltaville, Virginia, USA

    Umbra Junior Member

    Hi Armada-
    This is what I have seen-

    While in California, I cut a glassed over plywood boat to stretch it four feet for a customer. ( a thirty foot fishing boat, hard used )
    The boat was heavily glassed.
    It was about twelve years old, and I honestly expected the worst.
    To My surprise, the wood was in a perfect state of preservation.
    Because of that experience, and while everything else I have seen over the years indicates differently, as regards glassing over ply, I have to attest to the fact that it can, will and does work.

    Last year I replaced large sections of a fifty five footer, with a vacuum bagged foam core epoxy/eglass laminite because the existing glass over ply failed to such an extent i pulled the materiel away with My hands.

    I believe it has everything to do with the builder, making certain all ends are sealed, and starting with reliably decent marine ply from the beginning.
    The hull penetrations on the fishing boat had been epoxy coated when they were installed, and all materials that I saw when the boat was opened up were in excellent condition.
    If You are considering such an enterprise, the Gougeon Brothers are and excellent online resource for information, an wonderful answer source for the myriad considerations while building.

    I hope that helped~~~~~~~

    It CAN work, even if I don't like saying it, LOL.

    Encapsulating anything that is wet or rotted though, is just not going to have a happy ending.

    Sounds like fun!
    Good Luck, and remember, it's the endless details that make a long term success, so if it seems like it's taking too long, You are probaly going about it the right way, LOL.
  6. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Encapsulation is just as the word suggests. Total encapsulation is the only way you can insure the ply will stay moisture free. This assumes the coating isn't breached. Coating one side of a piece of plywood is done for abrasion resistance, typically with a cloth. Rarely is enough cloth used to add any significant strength to the plywood.

    True encapsulation can only be done in new construction or major reconstruction as the pieces have to be completely coated. Everything, each side, edge, fastener hole, everything, or the process is nothing more then a hard plastic bag surrounding the wood, waiting for moisture to get trapped inside with it.

    Additional glass, for strength purposes, will add considerable weight. You'll have to add quite a bit of material to the hull to strengthen it, this means the questionable transom will have to sustain more loading, as will the engine.

    Putting a bandage on a weak transom, like a plate, will had new life for a short time, but will kill it faster then if one wasn't used.

    As has been pointed out, 'glassing or epoxying over any bad lumber is just a formula for increasing the ills this boat has. It is a short term fix that will add considerably to the repair bill in following years to come.

    Transom knees are a common practice and a good way to transfer loads to the rest of the boat's structure. Again epoxy fillets, or 'glassing them to the boat bottom will provide some short term gain at the expense of the life of the boat, which will be shortened.

    You seem to want to add some strength, for a preconceived notion of needing to toughen her up for her new life on this lake. You also seem to want to take short cuts around the issues, plaguing this boat.

    Generally, I've found, you reap what you sow. If you want to fix the keel by slapping another piece of wood over it, repair the transom by sticking a plate on it, add strength with additional layers of 'glass cloth on the hull and otherwise add bit and pieces where you think they need to be, then what have you really done? Well, what you really will have done it not fix the keel, it will still be bad, not fix the transom, it will still be weak. You will have added a bunch of weight, effort, materials and money to the project and have a possibly stronger, certainly shorter lived, boat.

    Is this what you truly want? If not, then the transom can be repaired (more likely replaced) the keel can be repaired, the other issues addressed using similar techniques and methods that were used in her construction as well as new materials and methods that have become available since it's birth. If this is done what will you have? A good little boat, that isn't weighed down will some ill contrived repairs. A boat that doesn't need a bigger engine to drag her over burdened transom across the water. A boat that is near as good if not in better shape then it was when new. It's your choice, which way do you want to go?

  7. pungolee
    Joined: Jun 2004
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    Location: north carolina

    pungolee Senior Member

    You will have to work on the thing every 18 months, no matter what you do, these things need constant attention. If you have a repair option in mind to get you on the water for the season, go for it. Read everything you can, all the opinions, then decide what is best for you,your wallet,and your boat. Just wear a vest all the time under power, keep a bilge pump( a good One) ready to go, and your cellphone and marine radio charged, and go for it!
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