Replacing wood floor in Lund aluminum fishing boat

Discussion in 'Fiberglass and Composite Boat Building' started by Scrapper, Jul 21, 2012.

  1. Scrapper
    Joined: Jul 2012
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    Location: Springdale, AR

    Scrapper New Member

    I have serious rot in the plywood floor of my 17 ft. Lund alum. fishing boat. It will need to be totally replaced, and I plan to do it myself. Is it correct that pressure-treated plywood should not be used if fiberglassing is planned to encapsulate the plywood? If this is true, then is marine plywood what I need? How many coats of fiberglass and epoxy resin will I need for this to be done correctly? I have read that the fiberglass is not to protect the floor from water & rot...........but it seems to me that fiberglass would definately do that. Will it help keep the water out of the wood? I have not pulled the old floor out yet, but it appears that the stringers will probably be aluminum. All recommendations appreciated.
     
  2. GTS225
    Joined: Jun 2011
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    Location: Waterloo, Iowa

    GTS225 Junior Member

    Scrapper, there has been a number of reports of increased corrosion of an aluminum hull that has been in contact with pressure treated wood. Something about the chemicals in the wood reacting with the aluminum. I would suggest you use a marine ply, but you may be ok with a decent exterior construction ply if you plan on sealing it up with epoxy resins.

    You might also want to visit tinboats.net with this problem, too. There's discussion of the treated wood problem, as well as an entire section on home-brew builds of bare hulls to rather nicely done fishing boats.

    Roger
     
  3. jim lee
    Joined: Feb 2007
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    Location: Anacortes, WA

    jim lee Senior Member

    If you really want it to last, don't use ply at all. Use composite plate stock. Glass-core-glass. That stuff lasts pretty much forever.

    -jim lee
     
  4. tunnels

    tunnels Previous Member

    Forever is a pretty long time :?:
    Just need to plan out what you doing and what you want to use . Balsa as a core or foam ?? theres a great long list of foams so dont just take it at face value that its all the same because it isnt !,do your home work . This is a fishing boat so over build and get the milage to forever , where ever forever is !!.:D

    Presure treated wood of any sort its the chemicals the leach out in combination to salt water etc etc and it eats the aliminium away !! :eek:

    Its a lovely world we live in !!
     
  5. jim lee
    Joined: Feb 2007
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    Location: Anacortes, WA

    jim lee Senior Member

    隧道隧道隧道...你总是以为没有人做过功课。我们有。我们已经测试了每一个核心,我们可以找到。我们知道我们最喜欢的,我们现在建到我们所有的船只。

    - 吉姆·李
     
  6. Scrapper
    Joined: Jul 2012
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    Location: Springdale, AR

    Scrapper New Member

    Confused About Fiberglassing Boat Deck

    One article stated: Just use Spar Urethane on the plywood deck. One article said: Fiberglass and epoxy resin the plywood, but just on the top side, so that the underneath side can breathe. Another article said: Totally encapsulate the bottom of the plywood deck, and the top, and treat the holes also with epoxy (where it is or will be attached to the boat). Some of you have been at this many times. I would like clarification about this issue. I plan, tentatively, to use 3/4 inch marine plywood, because it is a fishing boat and I want a stable deck, and since the boat is aluminum and fairly light, it seems that the 3/4 inch plywood will give some weight to the boat and make it more stable in rough water???? That is my thought. Recommendations greatly appreciated.
     
  7. tunnels

    tunnels Previous Member

    Never assume

    Translated
    tunnel ... You always assume that no one has done their homework. We had. We have tested each of the core, we can find. We know that our favorite, we are now built into all of our vessels.



    My answer
    I work with a bunch of Chinese guys and i and sure some one rings then on a monday morning to tell them its work time .
    Can show and do something and next day they have forgotten same next day and the day after !,it just goes on and on to no where .


    So if you have done your home work then you dont have to answer !!
    I Never assume people have looked at everything , everywhere and as for testing well not many people ever test anything ,even resins !!!

    It its foam you picked on i hope it is core Cell !!! or H 100 divinicell or simular
    What is the glass you have chosen for the top surface and why and WHAT will you use on the bottom side and why ?? . The bottom and top layers can be quite differant from each other as they have completely diffferant loads to bare !!
    How thick will the core be ??
    This is depended on what the floor is supported on top of and the size and span of the panels , will there be any cutout for underfloor access for storage or simply to get to the bilge and maybe a pump or two ?
     
  8. PAR
    Joined: Nov 2003
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    Location: Eustis, FL

    PAR Yacht Designer/Builder

    Foam core and other man made materials will be quite costly, compared to exterior grade plywood and a light sheathing.

    The new PT treatments on plywood (CA) don't work well with epoxy. I'm not sure where you heard coating one side and not the other was right, but do yourself a big favor and don't pay any more attention to those folks, as they're clueless.

    The cheapest way is plywood from the big box store, but be sure it's rated APA Exterior, not APA Exposure 1. Exposure 1 is the stuff commonly used on houses, but it's not designed for extended exposure. It's only designed to tolerate getting wet from some rain for a few days, before the sheathing is covered by Tyvek house wrap and some other form of siding (aluminum, vinyl, clap board, etc.). You need APA Exterior, which is available from Lowe's/Depot.

    The way to do it is pull the old stuff carefully, so you can use it as a template. Cut the new plywood to fit, test fit until it's trimmed just right, then drill out the pilot holes for all the fasteners. Do a dry run and install the plywood, using the fasteners, when all is well and good fitting, pull it apart and start the epoxy run. Drill out the screw and fastener holes slightly larger then you need, so that the threads will not scrape off the epoxy when the fasteners are inserted, come time to install it for the last time. Ditto any countersinks you might have. Also round over the edges generously, so the 'glass cloth will lay down nice and neat.

    Coat the plywood (every side, every edge, every screw hole, etc.) with two coats of straight epoxy. You can do this in one day. Wait until the second coat has lost it's tackiness, then apply the cloth (6 - 10 ounce will be fine), by draping it over the plywood. Wet it out and remove any wrinkles, bubbles, etc. Let this dry. If you did a good job, this is all you need before priming and painting. The results will have a slight textured finish. If you want a smooth finish you'll need to fill the weave with some thickened epoxy. If you want more texture (for non-slip) add some texture from the local paint store. Just apply more straight epoxy in the areas you want texture then sprinkle the texture granules all over it, so that it covers the surface at least a 1/16" thick. When the epoxy cures, you can brush and vacuum off the excess.

    Log onto westsystem.com and systemthree.com and download their user's guides for product information, techniques and application guides. It'll nurse you through the basics. Of course they'll focus on their products, but the tips and techniques apply to all marine epoxies. Also look around for epoxy, as you can get it at half the cost of the major brands.
     
  9. Scrapper
    Joined: Jul 2012
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    Location: Springdale, AR

    Scrapper New Member

    Replacing Wood Floor in Alum. Lund Fishing Boat

    Hey, Man, I like what you are saying. I have done lots of carpenter work, so it all sounds logical to me. Would you go with 3/4 inch plywood for a nice steady ride, since the boat is light. My main question: Will the epoxy and glass help protect that deck from water (and thus rot)? One other question, Can I lay boat carpet over the deck, if I choose? Thanks again for great information.
     
  10. tunnels

    tunnels Previous Member

    Carpet !!
    Polyproperline type carpets are ok !! they are open weave donot hold any water and hard wearing and over time can be replaced if they get damaged .
    Household type carpets forget it no mater what they made if !!! How you going to fix it down ??
    I restored an older boat and rebuilt complete new aft decks and used poly carpet for the non slip looks good and easy on the feet and knees and have a colour choice !! dark colours draw heat ,dont forget !!:D
     

  11. PAR
    Joined: Nov 2003
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    Likes: 471, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    I've replaced lots of soles and floors over the years, just because of carpet (regardless of materiel it's made from). Carpet is what you put in your living room, not an open boat.

    I wouldn't use 3/4" plywood, just because you're decreasing payload capability and top speed, with no real gain. Your boat will not be tougher or stiffer as a result of a heavy sole. 1/2" is fine and 33% lighter too, which is always good in small boats.

    If the plywood is well coated, it'll stay that way, assuming you don't tear up the coating by walking around with spiked boots or something. As with any coating (like paint) you'll have to fix it when it gets dinged up. If you want color, paint it. If you want texture for good wet foot traction, use a granulated texture on the paint or on the wet epoxy.

    The addition of 'glass will improve abrasion resistance and to a degree, water proofing too. For a really tough coating, use Xynole, instead of 'glass cloth. It's 5 times as abrasion resistant as regular cloth. It uses more resin to wet out too, but this is the price you pay for the bullet proof method. Xynole doesn't cost much more then cloth of the same weight, so it's the logical way if interested in waterproof and great abrasion resistance.

    Lastly, all epoxy surfaces will need to be painted or clear coated. UV will eat up epoxy in time, so paint is the best choice. Porch and Deck enamel is the cheap way to go, and it's pretty durable too.
     
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