Pressure treated wood for decking?

Discussion in 'Boat Modification Journal' started by smallieworld, Jun 24, 2008.

  1. smallieworld

    smallieworld New Member

    Messages:
    12
    State:
    nc
    I am in the process of decking an aluminum boat and wanted to use some half inch thickness for some of the flooring. I have heard that it is bad for aluminum boats, is that true? if so, could glueing carpet that would not permit direct contact between wood and aluminum? painting the wood?
     
  2. AwShucks

    AwShucks New Member

    Messages:
    4,532
    State:
    Guthrie, Oklaho
    Don't use the treated wood. Best advice I can give you... you stand a very good chance of ruining the boat.
     

  3. justwannano

    justwannano Active Member

    Messages:
    1,003
    State:
    SE Iowa
    If you are going to go thru all that trouble just get a sheet of outdoor plywood and paint it.
    Ya know folks have been making boats out of wood for a long long time.
    They never had treated wood. In later years they used paint.
    have a good one
    just
     
  4. cantstopgrandma

    cantstopgrandma New Member

    Messages:
    955
    State:
    MD
    I wouldn't use it even with the carpet. The copper treating is going to leach out of the wood and it will still get onto the aluminum and cause you problems. We use wood poles at work (utility co.) that are basically treated the same way (copper knapp), and it leaches all over the ground where ever the pole sits for any length of time.
     
  5. whisker maniac

    whisker maniac New Member

    Messages:
    2,712
    State:
    arkansas
    If your gonna deck the boat you need to use marine grade ply wood not pressure treated ply. Marine grade is made to withstand water better than the treated wood. Treated wood is just pressure treated to help keep out insects, humidity, and to keep sunlight from damaging it. Marine wood is treated for water. But you still need to paint it to make it last even longer. The paint will seal all the pores of the wood and not let moisture in.
     
  6. justwannano

    justwannano Active Member

    Messages:
    1,003
    State:
    SE Iowa
    Marine plywood is a special order item here in Iowa.
    Its also kinda expensive.
    I'm sure most guys just use outdoor plywood. They use a different glue on the outdoor stuff.
    Put a good coat of Paint on it.
    I recently replaced mine. The last piece lasted over 10 years. It wasn't painted.
    I don't leave it in the water so it dries out every time.
    good luck
    just
     
  7. whisker maniac

    whisker maniac New Member

    Messages:
    2,712
    State:
    arkansas
    You could also take a piece of outdoor ply and then fiber glass it. That would really preserve it.
     
  8. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    Marine plywood has absolutely no treating to preserve it from from the elements.
    In fact some woods that certain marine plywoods are made from are not rot resistant species.

    There are a few things that make marine marine plywood suitable for boat use and the reason it is used.

    1. Marine plywood has very little to no voids. (Voids trap moisture and are
    a structural weakness).
    2. It has more plies making it stronger in compression and shear strength.
    That translates to using less thickness in alot of applications.
    3. The biggest thing that makes it marine plywood is the glue holding the plies together. You can take a piece of marine plywood and boil it in water, then you can freeze it in the freezer without the plies seperating.
    Your standard American plywoods that aint happening with too often.
    4. Marine plywood is substantially lighter then domestic plywood.
    To give you an idea there is a about 6 pounds difference in weight between a standard quarter inch sheet of pine plywood and Meranti plywood. If you go to Okoume(gaboon) you can save another 4 pounds per sheet potentially.
    Doesn't sound like much until you are looking at a stack of 16 sheets of plywood you are fixing to build a boat out of.

    One thing people generally dont realize is that marine plywoods arent made in the US. They are made in other countries. We do not have those tropical trees here however a marine fir is produced here. It's not lightweight and will check just like pine. Not worth the money in my opinion.

    Now for the floor in the boat.
    If it were me I would read up a little on boat building sites and get the jist of using epoxy or look at my canoe building thread in the kayak section here where there is alot of reading regarding epoxy. http://www.catfish1.com/forums/showthread.php?p=1087435#post1087435
    I would buy a gallon of epoxy some 6 oz cloth and some decent 1/2" exterior plywood.
    That is the cheapest longest lasting flooring job out there. It will last forever provided its not just forgotten. If you drop a scuba tank on the floor and gouge through the paint, the glass, and the epoxy it will rot as will marine plywood.

    I've worked with marine plywoods and domestic plywoods.
    Currently I'm building with a Chinese made outdoor Luan on a couple of canoes.
    I would rather work with marine plywood building anything rather then domestic plywood. It is a dream to work with from cutting, to shaping, bending, and sanding but I'll bet the farm I can cut a foot square piece of pine plywood and a foot square piece of marine plywood and throw them both in the woods and come back 3 years later and see which one is still there. The marine plywood will be gone. Its not as rot resistant as pine and like the pine its not treated with a thing.

    There is a great misunderstanding about what marine plywood is.
    Marine means its suitable for building boats, not that it doesnt rot.
     
  9. olefin

    olefin New Member

    Messages:
    3,908
    State:
    Texas
    My Kayot pontoon has marine plywood floor. The boat was in the water for a full 10 years before I got a boat lift. It stayed wet under the boat most of the time due to wave action. It's now 14 years old, the plywood is solid and under the boat looks as good as day one.
     
  10. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    Pontoons are a great situation for wood.
    There is air flow on both sides. There is nowhere for moisture to be trapped.
    Bet its fir too.
     
  11. Katmandeux

    Katmandeux New Member

    Messages:
    1,618
    State:
    Checotah, Oklahoma
    ^^^That's been my experience. Plain old exterior plywood, left unpainted and allowed to breathe, lasts a long, long time. My feeling, and that's all it is, is that any kind of coating or covering, if not 100% waterproof on all sides of the deck, will compromise this quality. I don't care for carpet or vinyl, for that reason.
     
  12. Mark J

    Mark J New Member

    Messages:
    9,407
    State:
    Four Oaks, NC
    I believe in a barrier coating like epoxy that prevent water intrusion and severely limit water vapor from travelling through it.
    Main thing about domestic plywood is that it is construction plywood and not made for boats. The native trees we make our plywood from are sap trees.
    I'm excluding the the oak, cherry , etc plywoods made for furniture and cabinetry.
    These trees like the pine and the fir will check. There is no question that they will check and when they do the interior plies are exposed to water and water vapor.
    Will it last a couple of years? Sure it will.
    There are 2 major downsides.
    If it lasts a couple of years, it means I have to do it again if I keep the boat and its going to cost again. Coulda shoulda woulda.

    The other is weight. You take a dry piece of plywood , glass it and seal it with epoxy and UV protect thats the end of it.
    If you dont then that piece of wood is left exposed to moisture and water and is free to soak it up making it heavier.
    Now some people might think that is being a little picky but let me explain something real simple. A sheet of plywood doesn't go far in a boat.
    It's multiple sheets and if we're talking floor most of your people think it needs 3/4 plywood just like your house is framed.
    3/4 exterior plywood weighs around 60 pounds a sheet.
    3/4 treated plywood (its always full of water when I buy it) weighs anywhere from 80-90 pounds by my scales. That is a 20-30 pound increase per sheet.
    If you go two sheets of the boat full of water thats 40-60 pounds of useless dead weight you are hauling around with no need to haul it.

    Epoxy is not expensive. People look at the price tag and freak. a gallon will go a long way.
    I can buy 3 gallons of an epoxy designed just for boat building and wetting out glass for 150 bucks for a 3 gallon kit.
    Thats enough to builld from scratch 2- 13 foot canoes and glass them inside and out.

    Nothing expensive about epoxy considering you are paying for it one time.
    Not every coupla years.
    My time is worth 3 gallons of epoxy at 150 bucks.

    I love the people that bring me a boat and say just fix it.
    If it costs 3 grand to drop a floor in it and rewire the whole boat thats what they want to spend.
    They dont want to do a 500 job this year and 2 years later do a 700 job and on the 3rd spend the 3 grand they should have spent 3 years before and been done with it FOREVER.

    When it comes to boats there is absolutely a right way, a half way right way, a shoulda stuck to golf way, a half assed attempt way, and a wrong way.
    The problem is the right way may cost more up front but economically is cheaper then the rest. One thing I hear alot.
    Well I only need it to last a few years because I'm selling it.

    Alot can happen in two years. In two years gas may be so high you decide to keep what you got instead of going with something bigger.
    Your finances may change and keep you in that boat.
    The other thing people fail to realize is that if its done right like a professional boat yard would do it it's a sales tool.
    Take pictures of the install showing what is under that floor and pictures of the products that went into it. A first rate job will add to the value as opposed to a shoulda stuck to golfing attempt that actually decreases the value of the vessel.

    About the only inch I'll give is on the plywood. Marine as opposed to pine.
    Marine is alot better plywood because of it's construction however it's not readily available and shipping a small amount like a sheet or two halfway across the country is a little over the top for the majority of people including me unless someone else is footing the bill and I also realize that if you go to the local plywood sources and start asking for Meranti or Okoume no telling what you'll get if you dont know a whole lot about what you are buying because in alot of cases the people selling the stuff know about as much or less then the people looking for it.
    Let me explain.
    The lumber yard guy says yea Mark I got 3 skids of 1/4" Meranti down here and I'll cut you deal on it if you buy atleast 20 sheets. How about 20 bucks a sheet?
    Thats the first red flag. Marine Meranti is going for around 42 bucks a sheet in 1/4".
    But Mark drives out there to have a look see thinking maybe this guy is nuts and he can actually walk away with the stuff at half price and thinking he'll buy all three skids at that price and just sit on it and maybe resale some of it.
    Upon inspection looking for the Lloyd's stamp and other marking he finds out it is indeed Meranti but it's not marine Meranti. It's actually an interior cabinet grade Meranti.
    This could turn REAL ugly real quick when you sink a few thousand into a project only to watch it delaminate in a few months.

    If you buy marine plywood online from the reputable boat building suppliers you have nothing to worry about. This is the BEST route for any boat project requiring plywood.
    If you buy from a local lumber yard you better know alot more about it then the guy selling it.
    This is where I'm willing to compromise.
    Anybody with little knowledge can go to Lowe's and pick out a sheet of exterior plywood.
    I can take the right products and make this pine outlive me however it's going to be heavier then marine plywood and I've hurt my future sales tool some by not going the marine plywood route.

    You have to think in long term economics where it winds up paying for itself rather then short term economics that will compound the cost over time.

    Boats are a hole in the water that you throw money into. No need or sense in making it worse then what it already is.
    Knowing the products is half the battle. The other half of the battle is utilizing them.
     
  13. smallieworld

    smallieworld New Member

    Messages:
    12
    State:
    nc
    Yeah the marine grade was over $100 per sheet and I needed 2 of those. Plus they dont sell 1/2 marine around here that I could find. I spoke with several people and went with the 3/4 ply advantech. It was used on a friends boat and has held solid for several years. advantech is the stuff they use in houses for the floors. it has a protective finish on one side because when they build these houses and it rains on it for a month it has to hold up to that. A couple people I had spoke to said they used it and it held for over ten years. I have already finished most of the front deck but for the lower floor (between the bench and the casting deck) I only need 1/2 cause it will not need to be as thick as my other flooring. I guess if I cant use treated and cant buy marine 1/2 I will need to get some sort of 1/2 ply and paint it. The boat doesnt leak and it will be covered. 100+ for marine or 20 for something I could see working fine not a hard choice. I will post some picks soon of the damage Some of the earlier stages can be seen on me other threads.