Using 4mm, 3 ply Meranti 1088 w/ FG epoxy encapsulation

by Thomas

I have read a number of articles in which it was stated that a stitch and glue boat could be constructed using standard 1/4” exterior grade plywood as long as the wood were fully sealed inside and out.

My question (as applied to a 15” sailboat) is; could such a sailboat be constructed with 4mm .157”, 3 ply Meranti 1088 with both inside and outside of the hull completely encapsulated in fiberglass-epoxy?

If you have had any experience using this construction, I would be very interested in hearing your comments.


Comments for Using 4mm, 3 ply Meranti 1088 w/ FG epoxy encapsulation

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Argie 15
by: Mick

I am currently building a Dix design Argie 15 foot with 6 mm ply stitch and glue.

You can see the blog at, it's the dinghy build page.

I can honestly recommend building a is so much pleasure to see it progress.

Mick c

Wood mm
by: Greg

In my opinion, it's always best to use a 9mm marine ply on the bottom, and 6mm for the sides and decking.

If you use 4mm, after wetting out the fiberglass, you should do an additional 3 epoxy coats on the outside of the hull.

I know it seems excessive, but like one of the other comments suggested, if something were to penetrate to the wood, you'd be in big trouble.

I might also consider adding additional stations when building so she has more ribs, thus less waver on the wood in between them.

The only other concern is that using such thin ply really limits your ability to scarf joints together. getting an 8:1 scarf on 4mm is going to take some very impressive planing skills.

I hope you'll post pictures if you get her built !!

What do you want?
by: Jack


It depends, doesn't it?

Are you going to trust you & your family's lives to something very lightweight on the Great lakes or are you using your boat in sheltered waters?

Are your fiberglassing skills good, particularly over the seams?

Is the boat hull and deck frequently reinforced or is it open and minimal like a "Daydream" design?

Just think about weather you are just trying to build a hole in the water that has little more strength than a bubble, or do you want something sturdy enough to withstand a dropped anchor & a stumble of a 250# crewman in rough water sgainst an unreinforced gunwale?

Cracks & seam leaks can get exciting when the shoreline is a ways off...


Plywood Sheathing
by: Anonymous

Hi Thomas,

Yea there has been perhaps too many articles along those lines.

Personally I would recommend always using Marine quality ply.

The epoxy will seal the exterior grade ply but if the epoxy/glass sheath is damaged and water gets behind it a lower grade ply will soon start to delaminate.

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