EPS Compsand board: Glassing only on outer surfaces? (deck & bottom)

General Discussion
1

Hi:

Basically, when it comes to compsand constructions, I read people describing their glassing schedule as

“Deck- 2x 4oz under, 2mm paulownia, 1x 6oz over”

Bottom 1x 4oz under, 2mm cork, 1x 6oz over.

But what does that mean? Couldn’t you just glass the outside of the skins after gluing them to the foam?

Thanks for any feedback!

**EDIT: **

Ok. This page won’t let me post any replies (reply button is dead) so I’ll just have to edit my post.

My intention was to make a 9"2’ noserider using EPS sheets and insulating them with 1/8-inch marine-grade plywood skins & rails to allow glassing with poliester resin without the whole thing burning up.

 

EPS/XPS is cheaper and so is poly resin so that’s the main practical reason. Also, it would be like a hollow wooden board in which foam replaces the air, therefore no need for a vent hole.

Three problems solved?

Oh, and a 1/3" stringer too.

 

I wish that reply button would work!

2

Yes you can just glass the outer layers, just make sure its super good glue.

3

I’ve always used epoxy to glue wood laminates on. Not always with cloth because those extra cloth layers tend to stiffen the boards up a lot. You want enough cloth wrap on the rails (16oz) or composite rails because that’s where the strength is. With an additional 2 or 4oz top and/or bottom under the wood the thing gets pretty stiff. Mals might be different. My longest board is 7’6"

I made one with 6mm aeralite skins and rails glued on with gorilla grip and glassed 1x4, 2x4oz. The skin holds the core components together regardless. Creased that one so maybe some cloth between layers would have been better.

4

Composit sandwich aim is to increase flexural and compression stiffness of thin composite by increase it thickness with a lighter material that separate layers of composite. So literaly a compsand skin have composite layers under and over a thickener matérial. But everything can be build with some success. If you want a surfboard with more buckling strengh you must increase buckling strengh of his skins, sandwich build is an effective way to go. Stiffer skins increase overall board stiffness. Stringers and/or stiffer rails are other way to increase overall stiffness but potentialy not as effective than sandwich against local buckle…