Micheal,
This is why I figured out how to do it with vacuum after my first failure.
I replaced about 20 sqft of my S2's deck and about 8 sqft of hull.
Matt Colie A.Sloop Bonne Ide'e S2-7.9 #1

Michiel wrote:
Hello,

Back in November I posted here about my balsa cored deck, which had
delaminated and had some rotten balsa in it. I got some great input
here and a variety of opinions.

I've just completed the repair and I thought I'd share my approach.
Sorry, no photo's - I was too lazy for that. I have not kept careful
track of my time and expenses, but I imagine I spent 40 or 50 hours on
it and about $300 in supplies.

Only part of my deck is cored, so the extend of the repairs was
limited. Perhaps about 10 square feet.

The balsa on the starboard side had let go of the outer skin, but was
completely dry. The port side was wet and most of the balsa was wet
and rotted. I found this out by drilling a lot of holes from the
inside and inspecting the wood that came out.

I repaired the delamination on the starboard side by injecting epoxy
thickened with glass microballoons, into holes drilled through the
inner skin and core about every 7 or 8 inch. This was very easy. I
filled caulk tubes with the epoxy paste and used this to be able to
quickly fill syringes. It would have be cool if someone would make
caulk tubes with narrow tips, so the syringes can be eliminated. The
result of this is excellent. The epoxy spread well inside the deck and
the deck is very stiff.

On the port side, I cut out the inner skin and replaced the core.

I used a rotozip saw with a carbide tile cutter bit to cut the skin
out, in pieces no bigger then about two by three feet. The balsa core
was attached to the inner skin, but entirely loose from the outer
skin.

I removed the old balsa from the inner skin with a chisel and then
ground the inner skin down with a 4.5" grinder. I also ground the
inside of the outer skin clean this way. This was an extremely dusty
process, with very fine dust.

For replacement core, I used scored Divinycell. The scoring helps it
to conform to contours. I first laminated this to the loose pieces of
inner skin. Trash bags filled with sand helped to apply pressure. I
left voids around holes for hardware, which I filled by injecting
epoxy after the deck was back together..

After I had these pieces of inner skin with new core laminated and
carefully trimmed to be the same size as the skin and with the scoring
facing up. I then laminated this to the outer skin from inside the
boat. I tried to use truck tubes to apply pressu this did not work
well. The tubes didn't press hard enough - they would just expand the
other way. Instead I used many strips of wood cut to the right length.

After this, filled voids between the panels and glassed the cuts, then
faired a bit and finally painted with a two part epoxy paint.

It looks pretty good. The shiny paint shows surface irregularities
much more then the headliner did.

Michiel