I agree working from the bottom can/will be a nightmare. I started out from underneath to repair my for deck. It was an area about 5-6 sq ft. After several attempts I abandoned it. I pulled out the trusty circular saw and cut out the deck. I then had to rebuild the lower skin. This required a makeshift mold. Once the skin was laid I was able to build up the core and upper skin. Unless the area you're repairing is small, say 1-2 sq ft, I would not ruin 2 days of work and $200 of resin/cloth/core material!

John
"Jionlin" wrote in message news:JeJCd.281274$5K2.77429@attbi_s03...
Brian Whatcott wrote:
On Tue, 4 Jan 2005 17:14:37 -0500, "jimk" wrote:

"Marc" wrote in message
...
I have discovered that I have wet core in several locations on my
cabin top. My limited experience with fiber glass has been with West
System Epoxies and I am comfortable with their use. The bottom skin
has been removed, the wet core excised and the top skin abraded and
prepped for bonding. I intend to wet out the underside of the top skin
and use Baltek Contour Kore AL600/10 to replace the core. After that
cures, I need to build up a bottom skin of at least 3/16". I need a
layup schedule that will give me max strength with the fewest number
of plies. This is a winter project. I will be able to maintain 40* in
the boat and intend on using the fast hardener. All suggestions are
welcome and hints as to technique or alternate methods are
appreciated.
When I did it, I used sticks to prop chunks of core in place overnight
(bonded to the top skin with thickened epoxy).
Then I wet the bottom surface of the core, and pressed the glass cloth in
place relying on the stickiness of the epoxy to hold it in place against the
force of gravity. It worked.

Just be prepared to get dripped on a lot. Work in overlapping sections.
Expect stuff to not always stay in place on the first try. Extra hands would
probably help if you have room.

Good luck.

Jim

...but this method could easily turn into a nightmare. Ask me how I
know....

Brian W

For my money, using vacuum greatly reduces the likelihood of getting a half-assed job.
Do you feel lucky today?