It is very important to prevent delamination
of the deck by preventing ingress or removing any moisture if possible - remember that polyester resin does not adhere well to wood - epoxy
should be used. Your deck is probably half-inch sheathing if it is the same as my former 1975 Catalina 30
. Unless you are able to leave the boat on the baking Nova Scotia
sunshine in the summer for a while, you might need to rent or buy a dehumidifier to suck the moisture out of your deck. Either way, all fasteners should be removed, of course. It will take time - it took a long time to seep in there.
All fasteners on a deck should be through or into a solid column of thickened and fortified epoxy
- just screwing them to the outer glass layer is a poor substitute, and sooner or later, water
will penetrate. Through-bolting is preferred to screws. Depending on how big the fastener is, the location should be drilled out over-size right through to the interior
of the boat, then if possible remove some more of the core
all around the hole as well. After drying out the deck, apply some duct tape across the inside face and fill the hole with thickened and fortified epoxy. When it is set, clean up irregularities on the inner and outer surfaces, paint
it if needed, and drill the nominal diameter hole and install your fastener. For my 1/4" bolts and machine screws, I drilled the hole to 1/2", so there was a 1/8" solid column all around the bolt.
This might seem a scary thing to do, and there is some time and expense involved but it will give you bullet-proof attachment of your hardware
, because the column of solid epoxy is locked between the f/g layers and will not compress under loading compared to your present situation where the plywood
centre will crush.
I would recommend that you use butyl tape as a sealant
which is obtainable and cheaper from RV stores - a big roll is only about $10. It is so much cheaper and easier to use than the advertised sealants. Mine were in use for 15 years of sometimes strenuous use and none of them ever leaked - even the windows.
You do not ever want to be faced with a delaminated deck. Incidentally, if you "sound" your deck by tapping it with the plastic handle of a heavy-ish screwdriver you will quickly find out if delamination
has occurred. The sound will change to a higher, musical, bouncy "plunk" compared to the more solid "thud" ones. The handle will bounce higher as well if the deck is delaminated. Look especially closely just down a slope from any fastener. Also look for any surface crazing (cracking) especially around any stressed hardware
like stanchions, etc., because they indicate a cracking of the f/g underneath. Good luck.