What is this under my teak deck...

[kellyp08]

Hi glhotka

I've reviewed your pictures. You've made a good start. But, trust me, it's only a start (unless you are planning on selling). You need to take up the entire foredeck and you may find that you need to deal with other areas ( like the side decks) as well. You may consider epoxying the thin teak planks to the under-deck and filling the fastening holes with epoxy holding new teak bungs. One problem, judging from your pictures, is that those "planks" are quite thin, not (in my opinion) adequate to hold the bungs - or as one of your pictures show - not even thick enough to hold the fastenings! Working as the deck works, the fastenings will will pop out the bungs again and you'll have to face the same problem in a few years.

Been here - done that!

These are beautiful boats with great amenities for cruising and/or living aboard. If your plan is to hang on to this boat, I'd do it right.

[Nicholson58]

Originally Posted by glhotka

I have a 51' Formosa. The deck is in rough shape (dry and cracking sealant between boards some loose, etc). So I opted to pull up a small section. I can see that there were several new holes drilled in the teak planks because there were slotted and phillips screws in them. Several of the bung holes had been filled with epoxy and when I removed them this is what I found.
It looks to me like it is some kind of an epoxy compound that may have been put down to hold the teak planks on (this is a plywood cored deck with Teak over the top).

So the question are as follows if someone happens to know them.

1) What is this under the planks, likely thickened epoxy or fiberglass?

2) How can I tell if the core is rotted below? I have attempted the tapping test, but this all sounds solid. I am assuming that is because of the additional glass (if that is what it is) that is on the deck. In this spot where I removed the planks, several were just rotted. They broke and in one case they are thin and you can tell about rotted through.

3) How would you recommend putting these back? I was going to use a grinder to get the surface flat, and then put thickened epoxy down and try to avoid screwing it in at all.

I have found that a moisture meter used from inside, headliner removed, is a good indicator of where the problems probably are. Start in ares you are sure are dry and then move into no-mans-land. The meter from above will be fooled by non-skid, paint, fillers etc.

I repair by drilling 3" holes with a hole saw from inside, dig out the wet stuff, dry, patch over using 15-oz Fabmat & epoxy, fill the void with pump-in epoxy & microballoon slurry. Check out my DECK photos. Send a PM if you would like the long version how-to. Member Galleries - Cruisers & Sailing Photo Gallery

[Oceandeep]

Great pictures. It looks like you have a gelcoat and then a layer of tar-like bedding compound under your teak. Based on what I see, I'm not sure you need to take up anymore teak planks unless they need replacement. You could probably just remove screws and inject penetrating epoxy into the core anyplace that looks suspicious. In the case of soft spots you may need to take more drastic measures and remove the teak, cut out the gelcoat layer with a shallow saw and get a look at the core material below. You may need to remove a section of core material and glass in a new core and then epoxy the gelcoat skin back into place after you clean it up. I would only do this if you suspect structural weakness underneath.

Best of luck and share more pictures as the work progresses

[Dolphinblue-BOB]

From the first picture, it is easy to see, that the bedding compound/ glue was not applied in a sufficient quantity. the differences where the teak touched it, and those where it did not, are clearly distinguishable. So there were voids beneath teak, and they represent a good path for water.

Secondly, I see that you succeed in taking the staves off without breaking them. This is definitely the proof that the bedding compound did not do it's work.

What is easy to conclude, is that if there was a water intrusion in the area below the teak, it had a chance to spread all over. Even if it did not find her way into the core of the deck, it is just a question of time. Also, the water trapped beneath surface, will "boil" and make the problem develop faster.

This is the almost the same situation we have found on a Formosa we restored completely. Check the sides of the deck. Are there any water residues coming out slowly, hours after the deck was washed down by rain or sea? (or hose). If so, the answer is simple, but not cheap.

[glhotka]

Thank you all to have posted comments again on the second set of photos. Like most things boats as you ask questions you get varying opinions. From KellyP's removing the deck to filling holes with penetrating epoxy. I intend to keep this boat for quite some time and will live aboard and sail her for the foreseeable future. So, I think it makes sense to do this right. I will try to post period pictures as I make progress. I am sure this is going to be a long slow process as I will be attempting it as we live aboard, so will try to do sections if possible.
I will be pulling the headliner and will go the moisture meter route as well to at least see vast differences in readings as suspicious areas.

Thank you all again for your wisdom and experience on the subject.