When I bought KJ, I had a surveyor check out the deck and hull since I was buying sight unseen so I would be sure I didn't have a wet deck core issue. A small area around the pulpit railing connection points showed moist not wet and there were some stress cracks in the gelcoat around the connection points also. Understandable for a 1976 boat. When I got KJ in the water and learned more about deck issues, I noticed a slight give under foot in the foredeck aft of the small forward hatch and out 6" on each side. This winter I purchased a moisture meter and sure enough it shows this area as wet. The water was coming from the hinge's through bolts for the deck hatch, so check yours. Cutting up the top or bottom layer of deck is out of the question for this small area, so I decided to add a deck fill assembly at each location for access to the core. You know, fuel, water or waste. I choose waste so no one would put liquids in the boat by mistake. I'm installing one centered between the pulpits aft connection points to the deck. This is a high spot and will give me good access. I will also use it as a rope pipe for my anchor rode. My kids sit up there so I wanted a flat surface, thus not a standard rope pipe. The rode will go into a plastic pan in the forward vee birth. The second deck fill will go centered aft of the hatch and centered between the hatch and the cabin rise. This fill fitting will be cur short and not penetrate the inner linner. Just a means to access the core. A glass pro could repair the hole later if needed. The fitting is my solution.
My logic is that I can pull out all the old wet balsa from these access points, dry out the void and pour epoxy from this highest elevation to fill the void and make the deck solid. I'm also opening the through bolt holes for potting and can gain access to the core form there.
The tools for core removal are long flexible scroll saw blades (These work very well in the limited access of the enlarged 1/2" bolt holes), a drywall keyhole saw (works the best), a car SS antenna in a drill with the tip bent 1/8" to tear up the balsa and hacksaw blades (these work well because the teeth are backwards and pull the material toward the hole. Here are some pictures of what I've done so far this weekend.
This shows the pulpit hole locations and my new rope pipe hole.
Here are pictures of the core removed from the rope pipe hole and the void extends down to each pulpit connection pint.
Note the length of the keyhole saw blade and the depth of core balsa removal.
Next are pictures of balsa removal via the deck fill hole I made aft of the hatch. The balsa was very wet and disintegrated in this area.
I have most of the bad balsa removed now and I'm drying the area with air tubes in each hole from and aquarium pump and my shop compressor using a regulator. I have small vinyl tubes in each hole. The compressor set up works best due to the higher volume of air. I have 4 heat lamps heating the deck and have poured distilled alcohol in the void to absorb the moisture faster. This will stay this way for at least 3 weeks or until I get dry readings. Then I'm pouring Mas Epoxy and filling up the voids. I'm using Mas because it doesn't thermally overheat with largeer volumes of epoxy as it cures, no blush incase i have to do two steps, its thin and its flexible when cured.
I'll keep you updated.