Deck delamination - serious or not

[anjolain]

When I bought my boat 2,5 years ago, one of the most decisive factors was, that she had almost a new teak deck compared to other similar boats on the market. When walking on the deck, it feels solid underfoot and one does not hear any creaks or other weird sounds. Therefore, I was not concerned about the condition of the deck, and it was not moisture metered prior purchase.

However, during my ownership I have noticed, that if someone is walking on the deck while I am down below, I can hear a sound - it is not like a loud creaking sound, but merely a "crap" almost on each step (sorry, not sure about the terms ) I can also feel the deck flex near the bulkhead, if I am holding my hand on the area, and someone walks on the deck over that area.

My theory is, that the old teak deck might have been leaking from the screwholes, and causing core delamination. And then the teak deck was replaced without paying attention to the condition of the deck core. The boat is now 22 years old and the deck has Divinycell-type foam as a core material.

The problem is that the boat has a beautiful, glued teak deck, so it would be a big waste of money and natural resources to open the deck from above to do the repair. And working from below will be pretty much out of the question, due to the interior panels etc.

I am a little bit confused, whether this type of problem is cosmetical or structural. Based on my experience, creacky decks are not that rare in older boats. My plan is to make sure that the teak deck is complitely watertight, so that the problem will not get worse. And maybe in 10-20 years, when the teak deck needs replacing, this issue will be fixed. I would appreciate to hear your thoughts on how common/serious issue is at hand and what would be the best way to deal with it?

[skipmac]

Well a few comments, questions and suggestions.

If I understand correctly the original deck was replaced and the new deck is glued and not screwed or is it both? If the new deck is glued, unless done poorly, should pretty much eliminate new moisture penetration. But if glued only did the installer address and repair old screw holes, moisture, etc?

Foam core is not susceptible to rot and not as susceptible to moisture wicking through the core as balsa. I have read of older, foam core hulls where the foam disintegrated into a powder leaving two thin fiberglass panels that were not attached. Not sure how big a problem this would be and if it is a concern with foam core on decks.

Yes there is often some flexing and noise even from a solid, good deck.

Would not hurt to do a moisture test but there are different opinions as the the usefulness and validity of moisture meter readings. At the least they can show relative differences at different spots on the deck which might help identify potential problem areas.

To really know what's happening you will probably have to do some destructive or at least invasive testing, ie drill some inspection holes to see what's inside. Do you have a head liner inside or is the ceiling directly the inner layer of fiberglass? Either way, find an out of the way or hidden area that is also an area that you suspect for delamination and drill in to see what you can see. Alternatively, maybe pull some fittings off the deck that are through bolted to see what you see there. May not work if the holes for the fittings were solid cored as they should be.

[anjolain]

Thanks for the quick reply!

Yes, the new deck is glued without any screws. I do not have any further information how the deck was installed. I have had some problems with leaky caulking, so I might be replacing at least part of the caulking during the next winter. Thus, I am not too impressed about the quality of the installation. But otherwise the teak deck is in good condition, and after the caulking repair, it should serve for many years.

Yes, there is a head liner inside, which might be difficult to remove without damaging the material.

[skipmac]

Was the leaky caulking through part of the deck or around a fitting? I would be much less concerned if around the fitting but somewhere in the middle of the deck would make me worry about the quality of the replacement?

And where are you seeing the leak? Inside I assume?

[anjolain]

I have detected the leaky caulking by seeing some parts of the deck remain wet longer than the surroundings.

No leaks to the interiors of the boat.

[CarinaPDX]

If you do any caulking replacement be certain to use the proper epoxy primer. The lack of a primer may be the cause of the current caulking coming off the teak. If you want to do it by-the-book then put some tape on the bottom of the seam before caulking as well.

It doesn't sound to me that you should be worrying a lot about the deck. If there are no screw holes, and the core can't rot, you have dodged most of the possible bullets. A little flexing or creaking is not of itself anything to worry about IMHO.

[skipmac]

Originally Posted by anjolain

I have detected the leaky caulking by seeing some parts of the deck remain wet longer than the surroundings.

No leaks to the interiors of the boat.

Is the leaky caulking you refer to in the seams of the teak decking or around/under fittings attached to the deck?

Not seeing the deck and wet areas you refer to I can think of a number of reasons why certain areas may appear wet that would have nothing to do with leaky caulking. Do you see water squishing up from under the teak planks around caulking that is not adhered to the planks? Is it possible the wet areas are just where water might be pooling after a rain? Could some of the teak is a little open grained or dried and a little porous?

[DSDman]

Before I started redoing my deck I drilled a hole through an edge on the fiberglass deck where there was a step down. So it basically went right into the foam core and then became a drain for any water that got into the deck under the teak. When I saw how much water was coming out that hole every time it rained I knew I had to fix it.

[DSDman]

The biggest reason was because of my climate. trapped water in foam core that then freezes over and over will eventually destroy the foam and crack up the deck.

[anjolain]

Originally Posted by skipmac

Is the leaky caulking you refer to in the seams of the teak decking or around/under fittings attached to the deck?

Not seeing the deck and wet areas you refer to I can think of a number of reasons why certain areas may appear wet that would have nothing to do with leaky caulking. Do you see water squishing up from under the teak planks around caulking that is not adhered to the planks? Is it possible the wet areas are just where water might be pooling after a rain? Could some of the teak is a little open grained or dried and a little porous?

I refer to the seams of the teak deck.

I have been able to fix most of the leaky caulking just by replacing the caulking at suspect areas. There have been a couple of areas, where water is pooling, so I have repaired those by injecting epoxy under the teak/seam, which has fixed this problem. However, this kind of spot repairs are difficult to do well during the season, since weather conditions are often far from perfect and the teak does not get dry enough (I am located in northern Europe).