Ok, who the (*#$ has been drilling holes into my deck?

[Yngmar]

This is a crosspost from the YBW forums.

After much rebedding of things and several rolls of butyl tape, I'm down to two leaks on my boat that I've been struggling to find. The one in question is in the forward cabin. I've borrowed a snake cam from a friend as access inside is very restricted due to a non-removable GRP liner. That and application of the hose on a sunny day narrowed it down to either the forward hatch, a U-bolt for jacklines or a hole in the deck.

I've rebedded the hatch and filled & drilled the U-bolt holes and it still leaked, so that only left the worst option. With the help of the hose I narrowed it down to a small area of the deck, which had some suspicious looking caulking. The caulking looked different from the rest - it wasn't deck caulking like the rest of the boat, more like black adhesive sealant that had failed in the sun after over a decade and was brittle, rubbing off black streaks and peeling up. I pulled on one part and a strip of sealant came up, and after scraping out some dirt I found the source of the leak - a perfectly round, evidently drilled ~4mm hole right underneath the seams in the decking strips (see photo below).

I then crawled around the foredeck with my nose down and found several more areas of different sealant, all in symmetric areas, two on each side - some of it peeling up as well. I can only conclude that this was part of the process of applying pressure to the teak decking when installing it, which as far as I know comes in pre-made panels (ply-backed) and is then glued (never screwed) into place. I previously assumed it was vacuum-bagged on, but perhaps in 2001 Bavaria instead held it down via these small holes from below, before installing the inner liner and bulkheads. Then filled the remaining seams and holes with nothing more than some black adhesive sealant. Is that a sound theory or does anyone have a better explanation for these holes? They're too symmetric and exactly at the seams to be the result of a deranged previous owner, not to mention too small to affix anything to them.

It's not a big problem, as the deck is cored with closed-cell foam and there are no signs of any core damage or delamination, so I'll let it dry out a bit, drill it for a clean edge and then fill the hole with thickened epoxy before applying actual deck caulking (ordered some TDS SIS-440) to refill the seam (cleaning and sanding the seam will be a bit of a PITA though). I fear I will end up having to do this to all the suspicious areas, of which there are about 12 in various places down the side decks. At least it'll stop leaking then!

[Symphony]

Perhaps at some time in the past that area of the deck has lifted and been repaired using the screws to hold it down. If it is securely bonded down then filling the holes and patching the seams should be OK.

[Yngmar]

Perhaps at some time in the past that area of the deck has lifted and been repaired using the screws to hold it down. If it is securely bonded down then filling the holes and patching the seams should be OK.

I've been over the whole deck and it's all of it that has these signs. Plus the failing sealant is in exactly the same condition as other factory sealant on the boat, so I'm 99% sure that this was done in the factory.

[njsail]

I have replaced several sections of deck and have still have to upload the photo essay to this forum.  I documented the entire process of how easy it is to fix deck sections. I sold in the spring but want to share the deck repair experience with others to show it is a relatively easy DIY fix.   Just time on your knees with the right tools.  Anyway....those holes don't go into the fiberglass itself.  The teak deck is laid with marine plywood epoxied to the original fiberlgass deck.  the original bavaria deck is a finished deck with your traditional non-skid and not raw fiberglass like some may have speculated.  The teak strips are then epoxied onto the marine plywood deck and the caulking applied to the channels.  When a deck lifts it is most likely the bond between the teak strip and the marine plywood that weakened and separated.  I still don't know the purpose of the sticky butyl buttons that are slightly counter sunk into the plywood and the teak deck.  I can tell you mine were not through the fiberglass deck at all - I pulled the goop out and checked.  Just wanted to provide my observation when I pulled the deck pieces up.   I still need to get around to putting the pictorial together and uploading it with some descriptions on work completed.   

[Spirit of Mary]

Yngmar,
From the pictures your seams look to be not in a good condition. Because Bavaria used up to the year 2002 ply-wood under the teak swelling is a high risk. Although the ply wood used should be water tight, it is not, when exposed to water for a longer time.  My Bav 38 built 2003 has a teak deck with a thin hard plastic underlayer. This is less risky for water penetration. I replaced all the seams (Sikaflex) 2 years ago. My boat was all the time in the Mediterranee, so high UV exposure. Already in 2009 the caulking showed detoriation. I replaced the seams with TDS SIS440 which should be better UV resistent, because it is modified silicon based. Removing old caulking, cleaning the seams, recaulking with taping at both sides of the seam and final minimum grinding took me and my partner 2 weeks (approx. 200 hours).

[Nigel]

... Bavaria used up to the year 2002 ply-wood under the teak ...

My caulking is all a bit dusty, I get black smears when wiped with a damp cloth. However, I'm pretty sure my teak is bonded directly to the GRP, it certainly is on the transom seating. Bavaria 47, 2000.

By the way, you can swear if you want to!

[Jam]

Hi
Makes me worry re my deck too as have Bavaria 38 ocean.  Have a few small leaks which I am still trying to get to the bottom of.  Also repaired a largish section that had lifted, previous owner did little with this boat.  I actually found a table knife under to deck section that had slide under the edge, I thought in felt odd walking on this area before, again a legacy of the last owner.  Was easy to repair, the weather was the main issue.  Perhaps could have made a better job though as seam could have been narrower where I had to cut to lift it.
I will be looking for these wee holes in deck too now, hopefully I do not find any,  good luck Ygnmar with your repair, let us know how it goes
John

[tckearney]

Hi all  I have just removed a section of decking on the Stbd Side aft of my B42 due to water ingress in aft cabin.  I had ascertained that the water was emanating somewhere behind the closet and running down between the back of the closet and the hull.   I have just found the same holes as Jngmar referred to. It is about 4mm dia and has definitely been drilled, probably during manufacture.  I assume it was to rectify a problem getting the ply under the teak decking to stick down.  I poked it through with a welding rod and the rod hits the upper level of the closet below.  God knows how many more there are in the deck.  Has "Clipper" ever said anything about this.  See attached pics

[Yngmar]

Mine are in strategic locations suitable to temporarily bolting the premade (on ply backing) teak decking down while the adhesive is curing. The locations certainly aren't coincidence, and I don't think this was a workaround, it was just how they were applied. It probably would've been fine and have lasted if they had used the same sealant (proper deck caulking) as on the rest of the deck, but they used some generic adhesive sealant which was murdered by over a decade of UV and is now failing everywhere. The deck caulking is mildly "dusty" at best and not a problem, but the black sealant used in these holes and used elsewhere on the boat (cockpit teak trim mainly and the sides of the cockpit seats) is rapidly turning into black marker and I'll have to scrape it all out and replace it eventually. Ugh.

For now, I'm prying out the failing sealant in the spots marked below, drilling the hole to clean up the edge and filling it with epoxy, before cleaning up the seams and re-caulking them with TDS SIS-440 as per their instructions. I've done a test piece (cut a seam into a piece of plywood) and this worked well. I'm using masking tape to keep the caulking under control as I don't want to sand down like you would when laying a new deck - there's precious little left of it as it is.

Locations approximate, I did this from memory. There are none in the cockpit and none on the aft deck, so they must've gotten that to stick by other means, or filled the gaps with the right caulking and therefore I can't tell (and there's no problem). The two long strips are a whole seam filled with dodgy sealant, presumably the sides and forward center piece came separately.

[tiger79]

I believe the panels are temporarily located by self-tapping screws into the deck, to prevent them moving whilst being glued (which is a vacuum bag process).

[njsail]

I think my deck  holes are different. Here is an old pic when i repaired a section of deck that lifted.  I cut a geometric pattern so when it was repaired it looked more like part of the deck than a hatch cut into the deck.  This section is in the starboard bowright iver the red dots in the diagram previously posted.  If you zoom in you can see 3 black holes filled with a black sticky goo.  I pulled the back goo out of the holes and there was no intrusion into the deck.  It was dpwn to the nonskid under the plywood substrste.  Not sure if there was a different process used or i found some other type of hole in the plywood - not the glass deck.  Anyway just wanted to share. 

[tckearney]

I also found these holes.  They are in the ply but not through the firbre glass deck.  They are also larger about 10mm and in a uniform line across the deck.  Mine too were just filled with a black gue.  I feel that these are just part of the process to allow the adhesive for the ply to get a better grip.  The holes that are through the deck are smaller at about 4mm. 

[Yngmar]

Been prying, drilling and epoxying on and off over the last couple days and today finally replaced the caulking with TDS SIS-440 on the foredeck. This seems to work pretty well by masking off the seams (36mm frog tape happens to be the width of the teak strips), then squirting the caulking into the seam and running a putty knife over new caulk and masking tape. Peeled off the masking tape right away before it could cure, then after 48 hours a gentle sanding just to remove any shinyness so it matches the rest.

The trick is then to not step into the fresh caulk and tread it all over the deck with your foot. That part I still have to practice a bit 

[Yngmar]

Just as a funny anecdote, today I found out Hallberg-Rassy is doing the same rubbish thing on their teak decks that Bavaria did on mine, only a hundred times worse: https://epoxycraft.com/teak-decks-part-3/

Theirs are laid up on the boat, so there are hundreds of holes from the temporary screws in the deck that are only filled with caulking that will eventually fail, instead of a dozen or so from when Bavaria attached the pre-laid teak-on-ply panels. Ugh.

[JEN-et-ROSS]

This story brings back nightmares.
12 years ago ago we bought our current 1991 Bavaria 38. an excellent price was negotiated due to the dreadful condition of the 'teak' deck. (thin teak bonded onto ply) The rest of the yacht surveyed well.
Due to the fact that the delaminating deck could not realistically be saved, our plan was simply to remove it and replace with a non-slip surface.
The teak/ply decking had not only been glued down but screwed down with rather more brass screws than indicated on Yngmar's drawing.
Most of the soft brass screws sheared off when we attempted to remove them, extracting the screws was long and very painful.
The final result was fine and no teak to worry about.
Though think yourselves lucky that later Bavaria yachts only have the holes and not the screws....!

[Yngmar]

Seen this crime in progress on a motorboat getting a new teak deck installed!

Enjoy your future mystery leaks 

[Petef]

This story brings back nightmares.
12 years ago ago we bought our current 1991 Bavaria 38. an excellent price was negotiated due to the dreadful condition of the 'teak' deck. (thin teak bonded onto ply) The rest of the yacht surveyed well.
Due to the fact that the delaminating deck could not realistically be saved, our plan was simply to remove it and replace with a non-slip surface.
The teak/ply decking had not only been glued down but screwed down with rather more brass screws than indicated on Yngmar's drawing.
Most of the soft brass screws sheared off when we attempted to remove them, extracting the screws was long and very painful.
The final result was fine and no teak to worry about.
Though think yourselves lucky that later Bavaria yachts only have the holes and not the screws....!

We bought our Bavaria 34 (2008) in much the same state. The teak panels lifting in various places. Made worse by the previous owner screwing the panels down with screws that have rusted and some definitely go through the deck. Where the panels have lifted it easy to get them up, but unfortunately some were still solidly stuck down  in places (Usually each end). This has meant that some strips have broken where I couldn't get the strip to release, and some that I have sawn using a multi-tool plunge tool so that I didn't need to break them. I had considered getting it all replaced by professionals but the Quote came to over £10K.  I'm in the process of cleaning the strips up to replace properly with TDS epoxy and then TDS sis caulking. My problem now is that some of the broken strips are too short in places, and getting hold of teak these days is like getting hens teeth. There is apparently a ban on importing teak according to various websites, so even if you can get it it's going to be expensive. Fortunately I have some teak strips left over from when I did my last boats cockpit seating (hopefully enough to cover the missing teak).

Back on Topic whilst removing some of these strips, I noticed that some of the strips had teak plugs in them (Like you'd find on a teak deck that is screwed down and covered with a teak dowel). These were indeed teak dowels but they extended into the plywood base and no further. It looks to me like they were used to prevent the strips from moving from side to side as they wouldn't hold the strips down. My deck will have more of these plugs as I am going to drill out the holes in the strips and plug them with some teak plugs I've made.

see pics
First is the deck with sample of lifted planks and screw holes
second is the plug as seen on the deck
Third is the hole the plug goes into

[Petef]

Seen this crime in progress on a motorboat getting a new teak deck installed!

Enjoy your future mystery leaks 

I replaced the crappy plywood faced with teak, with proper teak panels and used house bricks covered in polythene and Duct tape to weight them down and keep them flat with each other. Came out good .

[tiger79]

I'm increasingly happy that I specified fake teak on my boat.  It's now 8 years old and still looks like new.

[Ailatan]

Which brand did you use Tiger79?

[tiger79]

Which brand did you use Tiger79?

Bavaria's own DuraDeck, a factory option.