plywood skiff deck

[Pernicious Atavist]

okay, okay, i know, it's me again asking about red oak for my skiff. now, in spite of the warnings about rot, i've used it on my sailing canoe for years and have no trouble. to be fair, it's highly varnished and never gets left in the water. i rinse the boat and components after each use, also. knowing red oak isn't the best keeps me honest!

now, (i see cringing out there in wb land) i'm in the process of building a plywood skiff. (ply's not my first choice, but lumber was too $$ right now.) for my decks i want to use red oak (more cringing) plywood. what i've found at lowes/home depot is "interior use" ply. i inquired about using it and was told it would be fine as long as i had it sealed well, which it will be once i'm done with it (four-six coats of paint or varnish depending on where it is.)

so, true or false? can i seal it enough to keep it from delaming? i think not, but need to hear from y'all. keep in mind, this is a day-use boat that will be protected in storage, but will get used at least once a week in salt water.

thanks!

[NormMessinger]

I'd be inclined to think you can seal the surface veneer sufficiently with a penetrating epoxy. System Three has one that is not mostly solvents. On the other hand solvents may be necessary to penetrate. Kinda depends on who is selling what, eh? Anyway, I'd be more concerned about delamination. Except for door skin the few pieces if furnature grade veneers I've tested (water spilled on book case from aquarium, that sort thing) has come apart.

[High C]

Originally posted by ed maurer:
so, true or false? can i seal it enough to keep it from delaming? i think not, but need to hear from y'all.Not if only painted. That interior glue will easily absorb moisture and let go of the plies. Encapsulated on both sides with epoxy, yes, but paint is so fragile that it will allow water through as scratches and dings develop. Epoxy can make a fine looking bright finish, with real varnish over it for UV protection, of course. I assume you're doing a bright finish, since you want to use the oak ply? If you're planning to paint, then why go with the oak?

[Bob Smalser]

I'd sure research what kind of glue the manufacturer uses....resorcinol or casein or aliphatic or whatever.

Even epoxy won't prevent moisture from attacking those laminations. Polyester might do better, considering how most glass boat transoms are made (gag)...but polyester comes with it's own set of problems.

Usually cheaper overall to use the right stuff up front.

[Wayne Jeffers]

Ed,

One way to check the plywood you intend to use: you can cut off a piece of it and run the piece through the automatic dishwasher a few times. If it holds together without delaminating, it was made with waterproof glue. If it delaminates . . . do you feel lucky?

But like Bob said, it's usually better in the long run to use the right stuff.

Wayne

[Pernicious Atavist]

thanks, guys! i'll avoid the interior ply and go with my bcx, and <weep> paint it, too. i'll save the red oak for trim, seats, etc.. yeah, i wanted bright wood decks, but.....

[NormMessinger]

Now wait just a minute. Let's not be hasty. How big are the decks of your skiff? BCX is pretty crappy stuff and it is really hard to finish without the grain showing. I'm not sure this would work but here's what I'm thinking until you provide more information.

I made the decks on my first MacGregor sailing canoe, a la Iain Oughtred, with 1/8" oak door skin. It doesn't look that bad.

I laminated 1/64" teak veneer on to a piece of 1" okoume plywood for the transom for Prairie Islander.

Now, lets take you crappy CDX, fill the flaws in the D side, inject the voids in the inner plies with epoxy, and laminate a piece of 1/8" door skin to the D side. Door skin can be had in a variety of veneers. I'd put a layer of 6 oz cloth over the door skin, fill the weave, and bob's your uncle.

Of course I know nothing about your boat but what you said above so your actual milage may vary.

Best.

[Pernicious Atavist]

norm, the boat is 16'x3', 2' at the chines. think of a narrow sharpie. (extra-sharpie?) it's a light boat made w/ 1/4 ply, has chine logs, etc. no epoxy this time. i was tempted to cover it w/ epoxy/glass, but wanted to see how it would hold up with paint and some attention. the inside will be painted, but the red oak stem, transom, mast-partner and -step, and seats will be bright. that's why i was hoping for an oak deck. however, since this is a <$150 boat, it's as much experimental as anything else. it's my first, too.
coats upon coats of varnish and/or paint as appropriate are the order of the day and i was hoping the interior oak ply would work, but i just know from living here <1/2 mile from the salt, it probably won't. "dry" is a relative term here.

[NormMessinger]

If 1/4" is thick enough for your deck, I'd consider laminating door skin, back to back, if the price suits..

I covered a carpeted floor with a plastic sheet, spread epoxy on both faces, spread thickened epoxy on one with a knotched spreader, put them togeather on the floor and piled weight on them. I used sand bags.

You can epoxy the face veneers or not. Probably not since you are trying to keep the cost down. Thin the varnish 75% first coat, 50% the next, and lay down as many as you can hold still for. Your boat will be a beauty and if it falls apart in a few years you'll be in a better position to do it "right."

Now let's hear some other opinions.

[Pernicious Atavist]

hmmm...sounds like a plan, norm. i like the idea of thinning the first few coats of varnish--should soak in well! thanks!
awaiting other opinions, too.

[Buddy]

Try to find a dealer for Superply. It's fir inside, nice laun veneer outside, waterproof glue, damn few if any voids. Almost marine grade in all but price and label. We're using 1/2" in the blades of an always in the water 50 foot sternwheeler here. Protected with only enamel paint,it's doing great. Was about $18.00 a sheet.

[NormMessinger]

The last 1`/4" superply I got had a few voids in it but I poured them full of goop. As you say the face veneers are very good and the price is right. I think it would beat laminating door skins all to heck for this project. Should have thought of that earlier.

Oh yes. It is made by Roseburg Forest Products (http://www.rfpco.com/ply/super.htm) out of Oregon. That may help you track it down. I called them and got a local wholesaler and went from there.

[ 10-23-2003, 03:26 PM: Message edited by: NormMessinger ]