Steve wrote:
"rhys" wrote in message
...
On 17 Mar 2004 09:29:27 -0800, (jsheesley) wrote:
Do you guys have any advice, tips or tricks for laying up fiberglass
overhead?
Besides "avoid it like the plague"? Yes, but beware, it ain't a pretty
process.
I agree with the AVOID IT recommendations. I have done some core repairs
from below deck and learned a few lessons.
The best way to do it if you can, is to do the core repair from above. Leave
the interior glass alone and cut out sections of the topside deck.. Dig out
the bad core, glass in a new piece and glass over that, building everything
up to the original thickness.
Of course using this method, you will have to find a way to restore the non
skid pattern.. I'm still trying to figure a way to salvage the old patterns
and epoxy them back down onto the repair.. The boats I have worked on using
this method, had to have core repairs in numerous areas and needed new non
skiding anyway..
I did mine from the top. A dremel was used to grind the matching
pattern back into the deck by hand after the top pieces removed were
put back as closely realigned as possible. It is a tedious,
labourious, artistic, messy, rewarding task. Gobs of bog were
injected by refillable caulking tube, and slopped and spread and
reduced and increased, like icing a cake with coins in the icing all
by feel, to make the height of the restored deck the same. I
squeezed out excess and scraped it off the deck before it set up. I
used sandbags (not heavy enough, at first) to press the sections
down while setting up. Sheet plastic was used as a parting membrane
between the glass filler Aerosil mix and sandbags. It was messy. I
found that by driving small screws into places where the replaced
deck / core plywood was low, I was able to adjust the height of the
replaced parts, buttering bog just a little higher than the adjusted
screw heads. There were a few places where the goo sucked back and
required a gravity drip to fill at least most of the voids. I
increased the number of height screws in latter sections to support
the centers of replaced sections. One cannot be in a hurry to
accomplish this.
Too large proportions of aerosil speed up epoxy mix considerably.
Experiment first. I had one or two wads of goo actually go fizzy on
me, kinda like an epoxy foam after it set up. Got damned hot when
that happened. Heat, humidity, thickness, geometery of materials and
sunlight contributed timing snags, too.
Experience means doing it wrong until you get it right.
You could try release wax and poly resin to make a mould of antiskid
to be removed, to press down into the restored deck to redo the
pattern, or try using well waxed (dipped?) expanded metal mesh to
press in a pattern, I didn't try that, but was tempted, as I found a
piece of expanded metal that seemed like it almost matched my anti skid.
It might actually have been better to chainsaw the bad side deck out
completely, and rebuild it starting with a sheet of thin plywood and
plastic film held up under the hole with airbags or props, or
something, I don't know. The eventual extent of the probing for
rotton balsa was unknown at the start. I might have surveyed it
better by drilling some smallish holes from underneath. It was a
pain, but like lancing a boil, neccessary and worth it. My deck
fittings are all set in solid epoxy now, instead of having bolts go
through core, allowing water to enter.
After all, there is nothing half so much fun as messing about in
boats, right?
Terry K