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Posts: 416
Location: Madtown, WI | I'm going to be extending the back deck of my boat a couple feet and am trying to figure out what kind of wood I should be using. I assume marine grade plywood is ideal but it is expensive for a sheet and I'm reading that it doesn't come treated? So I'd have to seal it?
Can you use regular pressure treated wood from menards instead? I've read that the chemicals that they use can react with aluminum, looking for confirmation on that. It will be resting on an aluminum brace, can I wrap it in boat carpet so they will not be in direct contact? |
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Posts: 480
| marine grade plywood uses waterproof adhesive between the plys. Green treated plywood adhesive is water resistant not water proof. I would not use the green treated material. One alternative would be to water proof a exterier grade ply like BCX. Epoxy this top/bottom, edges and all holes you may make but it may be cheaper and faster to use marine grade ply. Some yards may sell you a partial piece
or one that has already been cut down. good luck |
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Posts: 280
| I used standard grade plywood (CDX) and sealed it with several coats of fiberglass resin on my rear casting deck. I did this after it was cut to size and all screwed together just before I put carpet on. 5 years and still sturdy as ever. |
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Posts: 416
Location: Madtown, WI | Do I need to seal the marine grade plywood? It's my understanding that marine grade plywood is not treated with any chemicals to reduced rot/decay.
I'd consider the standard grade plywood if I need to seal either way. |
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Posts: 208
Location: Sun Prairie, WI | When I did my transom last year I did a little research on what wood to use. Ended up using MDO plywood. It is used for signs. Has fewer voids than regular cdx but the best thing is it has a paper like finish on both sides so it nice and smooth and the fiberglass resin stuck to it very well. Its not as expensive as marine grade and not as cheap as cdx. I think I paid 50 bucks for a sheet of 3/4 Id look at this for the deck and seal all sides of it. the carpet will be nice and flat then also. Also I would use some sort of sealer where you screw through the wood. Just my $.02 |
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Location: 31 | stdevos - 7/8/2013 1:14 PM
Do I need to seal the marine grade plywood? It's my understanding that marine grade plywood is not treated with any chemicals to reduced rot/decay.
I'd consider the standard grade plywood if I need to seal either way.
I redid the casting decks on two of my previous boats and each time I used a 4-5 ply ½”CDX fir plywood (NOT PINE!) that I just painted after cutting out the different shapes. Obviously the stuff is less expensive, it's also lighter, and after painting and carpet should hold up for the life of the boat provided you're not leaving it exposed to the elements.
Keep in mind this is not a floor, it's a raised casting deck that will probably be undercover for most of his life anyway. Good luck!
Edited by Jerry Newman 7/8/2013 4:21 PM
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Posts: 797
Location: North Central IL USA | I wonder, do manufactures seal their marine grade plywood before carpeting???? |
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Posts: 202
Location: Angola, IN | You can use whatever you want. But how long it lasts, that depends on what you use and how you treat it.
Since you are putting carpet on it, why not just paint the wood? Go to Menards or Lowe's and buy a quart or two of oil based enamel and put several coats on it. It will last forever. Pay extra special attention to the end grain (the edges of plywood, the cut off ends of 2x4's etc....coat those extra well).
Since you are pretty concerned with cost, I assume you're not going out to buy polyester resin and sealing the wood in fiberglass resin. And that's okay. You can get away with a cheap quart of oil based paint. If you do use resin, one trick to get it to seal wood really well (to increase penetration of the resin into the wood substrate) is to head up the wood with a salamander heater or something like that, and thin the resin out with solvent. Do NOT add catalyst to the resin, and brush the hot resin onto hot wood and let it cool. When it cools, the resin will get sucked into the wood. It will still be very tacky (not cured). Then mix a batch of resin with some extra catalyst and spread that onto the wood, and all the uncured polyester will harden with the coat you just put on.
A trick I learned when I did my boat....
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Location: 31 | I just used untreated 1x2, 2x2, and the same lightweight ½” fir plywood on edge cut to the height I wanted. Mostly I supported and tied things together with lightweight aluminum angle... it was plenty sturdy and held up better than the rest of my boat.
I also just used exterior latex house paint… my thinking was it was formulated to last years completely exposed to the elements on your house. To each his own though, I remember seeing a casting deck somebody built on here a couple of years ago and they used treated ¾” plywood and 4x4s for the supports… I bet that aluminum boat rode better afterward! |
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Posts: 7
| You can save some money and go with CDX, and seal with resin or good quality paint. If you plan to keep the boat for quite a few years, take the extra time and seal it with polyester resin. Stay away from pressure treated plywood, if you do, don't seal it - it will rot from the inside out. |
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wood for decking