Composite ideas...

That hard white PVC core board for the transom, and nidacore with glass on both sides for the decks or structural foam with glass on both sides. Ankona uses nidacore with glass to make the shadow cast decks.

 

Plascore has a honeycomb that is substantially less expensive than Nida. If the decks are not going to have hatches than that would be my choice. If hatches, then foam.

 

DuckNut is right. If you're not doing hatches then go plascore. Higgs in Ormond on Nova has the 1/2" for $70/sheet if I remember right. If you're going to be mounting things to it or doing hatches, look at other materials. I used all plascore in my build (decks and bulks) and while its light, its a pain to finish the edges with thickened resin, sand it down, etc etc.

I used Aquaplas V for my transom from Piedmont plastics in Daytona, off Williamson. Its a little heavy but its pretty strong stuff. I got a "scrap" piece but she said they don't often have anything but full sheets.

 

Divinycell, Coosa, Penske, Michigan, Core Cell, etc... Every manufacturer has their own name.

Find a reseller near you or shipping will eat you alive.

 

A brand name for closed cell pvc foam. Its made by whipping meltted PVC and then extruding it flat as it cools. Its just a high density foam.

I used 1/2" for my decks and two 3/4" sheets for my transom. Its tricky to work with and get it to bed into your fiberglass though.

Its best to use a vacuum bag to press it to your wetted glass, but can be done by saturating the divynal cell with a microbaloon/ resin mixture. Or just a ton of resin.

 

Get you some Coosa and call it a day!

 

I used high density foam and glassed both sides prior to installation. if you lay up the finished side on a smooth surface it will save you a lot of sanding. see my build on this site (14' Malibu rebuild)

 

I used coosa on my build and loved how easy it was to work with it - minus the "black death" splitters it delivers. What is the foam that Little's Nano-Skiff used. There comments are right on about the foam being best used with vacuuming. I mixed epoxy with some thickening agent to a ketchup/mayo to seal all the holes that can make the foam heavy or give you nightmare air bubbles. I laid down the resin, let it gel and then put the cloth down in one process. I haven't used any other foam so I don't know what the pours nature of those products are like.