'Baltek ContourKore' if you want a balsa product. 'Core-Cell' for a polymer
foam. Look at defender.com for specifics.

There is also something called 'Klegicel" {spelling ?}.

Of course, this is like asking a bunch of rowdy sailors, "What's the BEST
rum ?". Stand back when you do, because the question will probably cause a
riot !!

Regards & Good Luck,
Ron Magen
Backyard Boatshop
{PS - Probably the *most important* factor is to make sure the remaining
substraight is BONE DRY before you seal ANYTHING between the deck &
overhead}

"Steve L." wrote in message
om...
I have some water-damaged 1" vertical end-grain balsa core in my
fiberglass deck. What is the best replacement material available?
Criteria for "best" are 1) suitability for blue water cruising
sailboat, and 2) thermal insulation factor. Cost of material, while
important, is probably not a factor, after all the labor of removing
all deck fittings, opening up the deck sandwich, routing out the wet
balsa, and then re-glassing. Thanks, Steve L.