ply wood for deck

[GregF]

Then the question becomes, is that strength important when those kind of stresses would have long since broken the welds on the hulls or pulled out the bolts in the cheap assed C channel they put most boats together with..

[Ron Burgundy]

I just got some popcorn......round two please

[goldnrod24]

Then the question becomes, is that strength important when those kind of stresses would have long since broken the welds on the hulls or pulled out the bolts in the cheap assed C channel they put most boats together with..

Bolts? Most of the cheap assed boats have their decks SCREWED to the C-channel.

When I asked a South Bay dealer about how their decks are secured, he said they are screwed. "They don't bolt your house together, do they?" I didn't know what to say, but later, I realized that the SILL of my house is bolted to the foundation (code?).

Guess there's a reason why Benningtons outrank South Bays in quality.

[GregF]

I am talking about the bolts that hold the C channel to the top of the toon. That is probably the weak link in the chain. If you get anything like those torsional forces specified, even on the cheapest plywood, you are going to be pulling those bolts like a zipper.

[FloterBoter]

Blowing smoke?

I could get into the semantics of engineering terms all day long if you would like, but I prefer to show ACTUAL results.

The attached table shows just how much better Meranti (Hydrocore 1088) is versus Doug Fir -and I stress that the table shows MARINE GRADE FIR which is head and shoulders better than any junky "concrete form" plywood you can buy at your local big box.

Take a good look at the 12mm column (3/4", which is the most commonly used on pontoons) and see for yourself. Meranti absolutely trumps Fir. While bending characteristics are pretty much equal this isn't really a consideration since they are both supported by stringers. Tensile, compressive and shear characteristics are far more important when it comes to defining overall "strength". When you can buy Meranti for almost the same cost as Fir there is no contest.

Oh yeah, Meranti has DOUBLE the screw holding strength - something that is sure to piss you off in a year when you start tripping over them in the middle of the night.

nice try. try to change the subject.

I could get into the semantics of engineering terms all day long if you would like, but I prefer to show ACTUAL results.

i doubt it. it's obvious you are a dabbler and don't know physics or engineering.
you are not showing actual results of what you touted--your "catastrophic failures".
you are showing strength test values for various plywood products.
no one said all plywood products perform equally. of course some are stronger
and some are weaker. some extruded aluminum decks are very strong.

you were spouting off like some expert about the "numerous opportunities for
catastrophic failure". fine--you ignored it once, answer it this time:
there are a lot of pontoon boats out there with "regular plywood" decks.
how many catastrophic failures in shear or torsion can you document?
NONE. because you are BLOWING SMOKE, nothing more.

engineering design is not about simply choosing the strongest, most expensive
components. you don't know what you're talking about.

and now you say...

Oh yeah, Meranti has DOUBLE the screw holding strength - something that is sure to piss you off in a year when you start tripping over them in the middle of the night.

lots of pontoon owners on this site, probably some who have a regular plywood deck.
OK, WHO TRIPPED OVER THEIR SCREWS IN ONE YEAR? HANDS UP.


omg, just stop.

[GregF]

The stress on the screws is not in the plywood anyway, it is in the aluminum channel.

BTW I was talking to the VP in charge of the lumber department of the largest lumber yard in SW Florida. (not a home owner store, a real building products company). He has been selling plywood for almost 40 years.
He says the only structural difference between "marine" and other exterior plywood is the plugging in the internal cores. It is the same glue. There are no internal voids in marine plywood. All layers are plugged. There are also other grades made that way. You just have to look at the spec. Marine is also "A" grade on both faces, something we really don't care about since you don't see either of them. "Marine" does not really guarantee any particular species of wood, you get what you pay for. He thinks I am overkilling it using MDO and a 7 layer "plugged" BC would be just as good.

The real issue is how well you protect the wood.
Well sealed CDX will last longer than poorly sealed marine plywood.

[georgiatoon]

IT IS NOT THE SAME GLUE. AND WHAT YOU WOULD BE LOOKING FOR IS CCA TREATED PLYWOOD. THERE IS A DIFFERENCE BETWEEN THAT AND WHAT SOME LUMBER PEOPLE CALL MARINE PLYWOOD THAT WOULD BE THE GLUE AND AS YOU MENTIONED 7PLY AND FULLY PLUGGED DEFECTS BUT CAN BE OTHER GRADES BESIDES JUST A. .

The stress on the screws is not in the plywood anyway, it is in the aluminum channel.

BTW I was talking to the VP in charge of the lumber department of the largest lumber yard in SW Florida. (not a home owner store, a real building products company). He has been selling plywood for almost 40 years.
He says the only structural difference between "marine" and other exterior plywood is the plugging in the internal cores. It is the same glue. There are no internal voids in marine plywood. All layers are plugged. There are also other grades made that way. You just have to look at the spec. Marine is also "A" grade on both faces, something we really don't care about since you don't see either of them. "Marine" does not really guarantee any particular species of wood, you get what you pay for. He thinks I am overkilling it using MDO and a 7 layer "plugged" BC would be just as good.

The real issue is how well you protect the wood.
Well sealed CDX will last longer than poorly sealed marine plywood.

[GregF]

Yeah, why would a guy who has been in the wood business for 40 years know anything about plywood?

You will be having a problem finding CCA plywood these days too.

[georgiatoon]

Alot of lumber yards sell what they calll "marine" plywood that is not cca and is not manufactured with water proof glue. After 40 years I'am sure he knows alot about different wood products but we are talking boats not buildings. As far as availabilty how much you want it's fairly easy to find.

Yeah, why would a guy who has been in the wood business for 40 years know anything about plywood?

You will be having a problem finding CCA plywood these days too.

[FloterBoter]

The real issue is how well you protect the wood.

Bingo.

[georgiatoon]

The proper wood is already protected "How many manufactures do you see covering there wood in all this other crap - none - Could that be the problem with this country people don't give a shit about doing things right or doing the right thing

The real issue is how well you protect the wood.

Bingo.

[GregF]

Find me one marine plywood manufacturer who will warranty his product in a wet environment without sealing it.

[georgiatoon]

Find me one marine plywood manufacturer who will warranty his product in a wet environment without sealing it.

Just one okie dokie would 40 yrs be long enough?

[georgiatoon]

Find me one marine plywood manufacturer who will warranty his product in a wet environment without sealing it.

Just one okie dokie would 40 yrs be long enough?

Heres a couple

PS warranty
CCA treated and kiln dried marine plywood for marine or exterior use. Lifetime warranty

against rotting and warping. Top side sheet has been sanded and all voids filled in with

"football looking" inserts




PNG forest products

http://pngfp.com/plywood.html
Marine plywood possesses the following features and benefits:

•BOND: Type A (Phenol Formaldehyde) which is dark in colour. The A bond is completely

durable under a marine environment, has a 40 year warranty and is heat, cold and

waterproof.
•Lowest available formaldehyde emission class level, E0.
•Manufactured to a minimum stress grade F14 (Higher stress grades are available upon

request)
•FACE GRADES: Marine plywood is manufactured with A grade veneer (mainly Hoop Pine) on

both the face and the back. The natural wood characteristics are ideal for decorative

applications that also require structural integrity.
•Lightweight and easy to work with. Solid core with no internal core gaps.
•Can be nailed up to 10mm from the edge and will still hold nail or screw fixings.
•STANDARD TOLERANCES: EWPAA quality controlled marine plywood has standard tolerances on

dimensions of length, width, thickness and squareness.


So there is still the right way and the cheap way
Just think if we still worked and built things the right way in this country

[GregF]

They are saying the GLUE is waterproof, so is any exterior plywood glue. They never say the WOOD is waterproof.
Show me the actual warranty document, not the puffery in the sales brochure. I bet you it says the WOOD has to be sealed. They even say "For best results, it is recommended to use high quality marine paints".

These warranties are BS anyway. When you have a failure they will give you the prorated value of the price you paid for the product, if you have all the paperwork. It does not include any labor or other materials. That is like the "30 year" guarantee on shingles. It is useless