Filling voids in plywood.

I am starting to build a boat from JEM plans . When I cut the first panel from yhe plywood , there is a big honkin’ void between the layers. Got any suggestions for filling it?

BTW, it is Home Depot plywood and yes I am cheap but I am having 2nd thoughts about this cheap wood. $30 worth of wood and $200 worth of epoxy may be a mismatch.

Looking for voids
You might be better off going and getting another panel of Lauan. Take a bright flashlight with you and you can use it to spot the voids in the ply by shining it from the back side before you buy. Of course they (HDites and customers) will look at ya kinda funny, but they don’t need to know the truth. You might be able to salvage the ply you already have by finding the voids and marking them so the hull panels miss the voids. You don’t really want them there. You could possibly drill two holes in each void and fill it with warmed epoxy from a syringe, but what a PITA. It’s not worth 10 bucks.

If you do need to get new plywood, save the stuff you already have for bulkheads, forms, etc.

Since this is a “practice” boat, you might be willing to try it anyway. You won’t break anything that you can’t fix :smiley:

“No one has ever been disapointed buying the best”

Void-less Luan
You don’t have to spend the money on marine plywood to get the “no void” guarantee. It won’t be quite as cheap as the HD luan, but you can find lots of reasonably priced ply with the “no void” guarantee if you look in the right places. One Ocean Kayaks has a great article on plywood on their site.

I have no idea what he’s like in person but anyone with that kind of knowledge sharing is worth knowing about. Cool resource.


– Last Updated: Mar-02-05 10:04 AM EST –

Void filler: Epoxy thickened with a little wood flour. Smear it in the voids.

Quality Luan: I'm guessing you mean you don't want it shipped in. If that's the case, I've found that around here, Lowes has better quality
plywood than Home Depot. Not sure if that's the case near you.

But I'd look in your phone book under lumber. Call a couple places. Tell them you want exterior grade, light weight, no voids, and a soft species wood (no oak or anything like that). See what they have to offer. Don't let them talk you into interior grade. You NEED the exterior grade glue that holds the plies together.

I used some stuff called "Bahama Plus" that was pretty good. Still had a few voids to deal with but not too bad.

I can understand your dilema about not wanting to spend big $$ on plywood for your first boat. But everyones' preferences are different.

Jim - If I remember correctly, you're in SC. If you decide to go with marine grade ply and need it delivered, give these guys a call:

If you're along their normal route, they'll deliver free to a business address. So if you know someone who owns a store or shop, they drop it for free.

A friend also recommended
underlayment which is supposed to be void-free.I am going to use the void one for a template, so it wasn’t a total waste.

Home depot can order void free for you but not worth it. Lowes as JEM says has better but buy carefully. I lucked out with a local lumber yard that has Birch and phillipine mahoganey void-free underlayment in 1/8, 1/4 and 3/8. Great stuff. Look for these in your area.

Good luck with the boat!

Some umderlayment is certified void free.You haveto ask at the store.

I used Superply. Certified void free and exterior glue. I got mine at Menards around $15 a sheet.

I took JEM’s advice and went to Lowe’s.
I got exterior hardwood plywood in 1/4" (5.2mm). Not a single void showing on the edges. I am ready to start cutting again.

if you find a void…
fill it in with an epoxy-woodflour mixture.

Seeing no voids on the ends is a good sign you probablt won’t see any when you cut.

Plywood type is a matter of builder preference and the contents of the builders wallet!

I said for String to check out Lowes because I know this is his first boat and he intends on building others. May not be the best choice for all builders.

If a builder wants the best, marine grade BS1088 Okoume is the way to go. But it’s expensive.

Out of curiosity Jem,
What would a 4x8 sheet of quality wood cost? I am not contemplating building, I just want to know what teh “WOW” factor is!


depends on where you buy
A 4 x 8 sheet of top-quality Okoume (the best stuff) can run you anywhere from about $30-$45 depending on where you buy from. More if you need it delivered. It can be hard to come by depending on where you live.

It’s so comparitively expensive because its quality is garunteed, is at least 20% lighter than most other plywoods, and is very nice to work with. Very minimum amount of splintering or cracking. And it looks very pretty if you go for a natural wood finish.

It’s an almost frustrating decision whether to use it or not. Especially for a first time builder. You want to keep costs down but you also want to make sure you boat can be light as possible.

I’m a big advocate of going cheap and simple for the first boat built. Even build a simple bookshelf using stitch and glue methods. There’s a learning curve to overcome that equate to 10+ pounds on a boat in the 15’ range.

it isnt just the voids

– Last Updated: Mar-05-05 12:49 PM EST –

or glue for that matter. an important factor is ply thickness. i mean the thickness of each ply in the sheet. each ply in marine grade is the same thickness and there is no 'filler core' as is common in lumberyard plywood. even expensive lumberyard 'birch' and 'oak' plywood has a core that is low grade 'filler' you end up paying for the thin, expensive outer veneers and the interior is cheap low grade wood. i bought some beautiful 4 mm luan marine grade that was AAA, each ply was equal thickness A grade. thats what you get with marine and i think its worth it. the best sources i've found here in sc are harbor sales in maryland and

After the fact but you can use it in the future:

You can ‘hear’ voids in plywood when you tap it lightly with the tip of your finger or use your fingernail. Also if you look along its breadth you can usually spot larger bubbles.

good points…
yes that’s also very true. The consistency of the plies comes into play.

It’s especially important when you get into building power boats.

40-45 $ a sheet for the good stuff