Cheechako, the point i was making about that F-board was that while the weight per square foot was certainly light you have to be realistic about how and where you use it, a couple of examples of where we used it inapropriatley imho was for the cabin sole
and for the cabinet fronts above the sink in the heads.On the sole we used 3/4" F-board with 1/4" T&H ply laminated to the top surface, now this boat had an aluminum
space frame with all cabin sole
support structure out of aluminum
angle closely spaced breaking the panels
up into fairly small sections, i bitch that its ridiculous taking an expensive lightweight material and then gluing on heavy T&H ply to which the powers that be say, yeah, but its still lighter than 3/4" plywood
to which i reply, but who the f#%k would use 3/4", use 1/2",by the time i backfill the edges the f-board will be just as heavy but not as tough as straight plywood
to which im told, yeah but plywood is not hi tech. In the other example of the cabinet face we take 1/3rd of a $300 sheet of F-board, cut out most of it to install Plexiglass(heavy)sliding doors leaving just a perimeter,then routing out 3/8" of the honeycomb between the skins on all edges and backfilling with thickened epoxy
,teak veneering it and then gluing it in,what a waste, it would have been just as light to build a light wood faceframe and much cheaper and quicker. Now it was perfect for areas like bulkheads,bunk tops etc, large areas with minimal backfilling.
I dont believe it makes for any stiffer panel than foam or balsa with a comparable core thickness and skins. I would say all things being equal, the balsa will be heaviest,the honeycomb the lightest and the foam in between and all about equal in stiffness. My son is planning to build a cruising cat and we will likely use balsa for the hulls and decks,nida core for the non structural sheetgoods and plywood for the main strength bulkheads/crossbeams. There will be at least a foot of solid glass down the hull centerlines with no core for sitting on the beach.