Cheap Plywood

Good morning fellas,

For our last Everglades Trip we needed a boat for someone who didn't have one. I did the math, and figured out that I could build the "Cheap Canoe" from for about $200, using some new stuff and some left overs. $200 is about half of what it would have cost to rent a canoe/kayak in South Florida. In order to get a boat built for that price, I used 5.2mm underlayment from a big box store.

I used this plywood for 2 reasons, experimentation and cheapness. The "internet" is mixed on this issue, some rave reviews and some avoid it like the plague reviews. After building one "cheap" boat with it, I am now firmly planted in the avoid it point of view.

Our trip got cut short due to weather. So, 3 days in the Everglades, the trip down and back, and 3 months upside down in the yard, has resulted in a spot of delamination/bubbling on the inside, about 12 inches by 10 inches. Repairable? Yes.

If you must use cheap plywood make sure that it is fully encapsulated in glass, which adds to the cost and time to build. I had 2 thick coats of epoxy on the interior of this boat and it still delaminated. The exterior was glassed and so far seems to be holding up.


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RE: Cheap Plywood

Plus 1 on everything JRC says. I built a Cheap Canoe out of Okume 12 years ago and it's still going strong, Glass only on the bottom. It used 2 sheets of 1/4" BS1088 Okoume plywood, one of my first purchases from CLC.

Underlayment with 4 oz glass comes to about $65/sheet for the wood, glass and epoxy, with the weave unfilled. That's vs. $90/sheet for Okoume with no glass. For the Cheap Canoe, that's a $50 difference in the price of the boat materials. It's actually less when you add in the cost of material to fill the weave, sand it smooth enough to paint, etc. That's got to be at least another $10 per sheet or $20 for the boat. Then there's the labor. But let's keep this simple and let the underlayment have a bigger price advantage than it actually deserves.

So even though that may look attractive, a glassed underlayment boat is not the same as a BS1088 Okoume boat. It may be watertight, but it's not as strong. That's because the marine ply has 5 solid plies and underlayment usually has only a chopped wood filler with a thin facing ply on each side. That's not a problem under floors, where the stresses are compressive, but for boats, where you have shear and tension too, it can be disastrous. Eventually, the face will delaminate from the core, even without any water getting into it, just from the flexing.

$50 over 12 years is just over one penny a day, not a bad price to make sure that the boat lasts. And in reality, the difference is actually less, under a penny a day.



RE: Cheap Plywood

So far about an hour cutting into the plywood to get it exposed enough to dry out. Will post photos soon. I am locked out of my account. JRC

RE: Cheap Plywood

Delamination before

RE: Cheap Plywood

Delamination before

Deosn't look too bad. Pasted wrong link before.

opened up

Moved into the garage. Cut open to dry out and epoxy back together later. This boat is only 4 months old and only been on 1 trip. :-(

RE: Cheap Plywood

Happier photo, my dad in his WD12 and a friend of ours in the Cheap Canoe, in the Everglades.

RE: Cheap Plywood

Yep, you get what you pay for.  My neighbor recently gave me a One Ocean Cirrus Hybrid that someone built from plans out of Luan from a big box store.  It paddles great and the the strip deck made of cedar (also from the big box store) is still beautiful but the hull, is falling apart, and this kayak is only five years old.

I am going to cut the deck off of it with my saws all and build a new hull for it out of Okume.  

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