Evan Gatehouse wrote:
wrote:
I discovered that most of the balsa core mateiral in the deck of my
18-ft boat is either rotten or fully wet. I am in the process of
removing all the core material from the entire deck. Now I need to
figure which alternative core materials I should use for these two
different areas:
1. Deck area that don't have any weight-bearing hardware.
2. Deck area where the T-top is anchored on.
For the deck area that don't have any weight-bearing hardware, I am
thinking of getting something like Corecell or Divinycell that are made
from PVC and won't rot. I am thinking of getting them in plain sheets
instead of sheets that have been scored (cheaper and in the correct
thickness). But according to the supplies web site, plain sheet of
those materials cannot be contoured to curved shapes. I am wondering
whether I can at least bend the plain sheet just a little bit -- like
1" drop for every 30". Is the plain sheet so rigid that I cannot even
use a bag of fertilier to conform it to a slight curve on the deck when
I bed it with wet epoxy? The other question is whether epoxy will
adhere well with those synthetic core materials.
For deck area where the T-top is anchored on, I am thinking of using
either marine grade plywood encapsulated with epoxy or many layer of
fiberglasses and epoxy. Will marine grade plywood still rot? Which
material is better for this area anyway?
Thanks in advance for any suggestion.
Jay Chan
Plain Corecell will bend that sort of curve easily. It's a bit more
expensive than Divinycell but resists impacts better. Do you drop a
lot of heavy objects 
on your deck?
Epoxy sticks very well to all these synthetic cores.
If you use plywood:
- coat it with epoxy as you suggest.
- when you go to through bolt/screw on the T-top, first drill an
oversized hole. Then fill the hole with thickened epoxy. Wait for it
to cure. Then drill the smaller hole through the thickened epoxy.
Even if the caulking fails, water shouldn't get to the plywood.
I'm not wild about using plywood as a high density core but real high
density core is very expensive. (except for www.bateau.com's Renicell
but you probably don't need a whole sheet!)
Evan Gatehouse
Thanks for confirming that Corecell plain sheet should have enough give
to be bent slightly. I also have a feeling that Divinycell is cheaper
than Corecell. But this may become irrelevant now. Turn out the
boating supplier cannot ship large plain sheets (store pickup only). I
may be forced to buy small sheets that have scored. Oh well...
Thanks for the tip of using a combination of marine plywood as core
material and epoxy bedding to secure the T-top. This sounds very
practical.
If you don't have a good feeling about the use of plywood as core and
high density synthetic core is very expensive, I am wondering what you
would have suggested.
What's about the idea of using fiberglass and epoxy alone (solid thick
fiberglass, no core) without using marine plywood for the T-top? Then,
there is nothing to rot and must have a lot of strength, and I don't
need to buy a whole sheet of marine plywood. The only thing that I am
not sure is whether this solid fiberglass is stiff enough. If it has
some give, I am afraid that it will transfer load to other anchoring
points of the T-top and may cause spider crack on the gelcoat in the
other anchoring points (the T-top has two anchoring points on the deck
and four anchoring points on the console). I am just hoping that a
5/8" thick solid fiberglass deck will be rigid/stiff enough to absorb
most of the load. Any idea?
Jay Chan