Plywood question

[Jim Willemin]

Given the wide variations in quality in construction lumber these days, does anyone have any insight into how to estimate the voids in a sheet of ply (say ACX) before cutting into it? (Without breaking down and getting stuff like marine plywood manufactured to a spec defining no voids, that is.) I'm thinking of building a little boat this winter, just something a little more stable than my canoe for fishing small water (knockabout, not heirloom quality; oars, no motor), and I'd of course prefer to get stuff as free of voids as possible without spending too much. Any suggestions about what to get or what to avoid?

[Leon]

A boat? I think I would not want to scrimp on the wood, I'd go for something with no voids.

[dpb]

I'm sure there are manufacturing standards on the maximum for a given grade to support the load ratings for span, etc., but I've not looked for them specifically. I'd start w/ the plywood manufacturers' trade associations and see what you can find.

But, I don't think it will help very much for construction grade material as I'm sure it can have a significantly higher void fraction than you will want and still be suitable for purpose.

Other than that, there's no reason that interior voids (knotholes, small voids between pieces, etc.) are actually a defect so there's really no reason to expect it. The one thing that does correlate ime is cost--the cheap imported stuff is that for a reason. Often, it isn't even stamped as conforming to trade assoc grades.

I'm not a boat builder but would seem to me that it wouldn't make sense to put the effort in w/o using something rated for the purpose. Otherwise, just buy an old knocked-around skiff from somebody else.

--

[Doug Winterburn]

[Pat Barber]

Marine plywood is the answer and it would appear that you knew that. No construction grade plywood is free of "all" voids.

Your other choice is a solid wood boat made from from juniper/cypress. That was the choice for many centuries.

Given that you can buy a fiberglass boat for the material cost of a wood boat, why go to all that work and trouble ?

A used jon boat sounds like something you need.

Jim Willem> Given the wide variations in quality in construction lumber these days,

[spaco]

Even worse tha just "voids", I am seeing a lot of just plain delamination!!!

Pete Stanaitis

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Jim Willem> Given the wide variations in quality in construction lumber these days,

[dadiOH]

The difference in cost between exterior fir ply and marine grade Meranti is negligible considering the small anount you'll need and the vast effort in building even a small boat. Note that there are two (at least) grades of "marine"; you don't need the super dooper one.

[Lew Hodgett]

Buy a boat.

Don't even think about building one.

You will spend less money buying a finished boat than you will on materials to build one, not to mention the time spent building it that could be spent fishing.

BTDT

Lew

[clare]

And for a BOAT he definitely needs waterproof glue plywood. He will want at least a b grade veneer and a "A" or "B" bond. B is good for about 2 years of exposure to wet - so MIGHT be suitable for a cheap boat. Anything less than a "B" grade veneer will have voids, which in a "C" grade may be filled with either wood or wood byproducts. (not good gor getting wet)

An ACA would be suitable (appearance grade both sides, with a grade c inner ply structure(no voilds, filled)

[Phisherman]

Use a cabinate grade ply. HD has some cut into 5x5-foot sheets. Other ply with voids should be...avoided.

[CW]

[Puckdropper]

"CW" wrote in news:ROKdndOfAd7oCrzUnZ2dnUVZ [e-mail]:

Only if your time spent searching for the right thing means nothing. Personally, I'd rather avoid the whole shopping headache and just build my own. Several hundred dollars buys a lot of wood, or just one visit to a medical professional.

Puckdropper

[RM MS]

I assume you know that birch plywood wll disintegrae when wet? Marine plywood isn't so much wet-tolerant wood, but wet-tolerant glue in it. Also, no voids. Also cost a few bucks. We have used Wolmanized plywood for rougher boat jobs, and it sems to handle near-constant wetness for at least a few seasons, but s not as finely finished as true marine ply.

[RM MS]

I assume you know that birch plywood will rapidly delaminate when wet? Marine plywood isn't so much a wet-tolerant wood, but wet-tolerant glue in it. Also, no voids. Also cost a few bucks. We have used Wolmanized plywood for rougher boat jobs, and it sems to handle near-constant wetness (inner floorboards, transom pads, etc.) for at least a few seasons, but s not as finely finished as true marine ply.