Rotten bulkhead repair

[hennypenny]

My Bavaria 31 had an anchor windlass installed approximately 10 years ago which is located in the chain locker on a shelf. The wires run through the v berth bulkhead but weren’t sealed properly and now the lower right hand side quarter of the bulkhead has rotted and the foam lining on the side of the cabin has also repeatedly gotten wet and is falling off. Water comes in every time it rains or when waves come across the deck.

How easy would it be to replace just a section of the bulkhead, and what are the options to do this. Or is it better to just replace the whole bulkhead? Is it possible to do this DIY?

Thanks all look forward to hearing your thoughts!
Read more at http://www.ybw.com/forums/showthread.php?525616-Repairing-a-rotten-bulkhead#3Ilrlgogoo434mPU.99

[Yngmar]

West System's excellent (and free) instruction manuals have all the information you need: https://www.westsystem.com/instruction-manuals/

The one you want to read in this case is the Fiberglass Boat Repair & Maintenance Manual.

[hennypenny]

Thanks - do you know by any chance are the bulkheads plywood or solid?

[Yngmar]

I'm not sure which bulkhead you mean, as our boat is a different design and I'm not familiar with the Bavaria 31 (and you didn't state which year).

Generally on our 2001 J&J boat, the main bulkheads dividing the cabin are varnished marine plywood tabbed on with fibreglass (hidden behind trim) and the smaller ones (such as in the fwd sail locker) are airex foam cored GRP with grey flowcoat where visible. The horizontal windlass shelf is cored with plywood, but luckily that wasn't rotten and I protected the exposed areas with epoxy since, which I think is a good precaution if you're doing work in that area or have the windlass out anyways.

Since you already have a hole (where the cables go through), it should be easy to shine a flashlight in and see what the core material is made of. Airex foam is a light green and crunchy when poked. Wet timber is dark, and soft and crumbly when rotten!

[Symphony]

Bulkhead is almost certainly plywood veneered on the cabin side and probably coated in a white laminate or flowcoat on the side of the locker.  Repair should be straightforward but a bit messy. The West guides are good on technique. Although the bulkhead is bonded to the hull it is not strictly structural but it is for obvious reasons important that you get a good watertight finish on the anchor locker side.

[Salty]

 I’m not familiar with the construction of a B31, but on my B36(2002), the aft bulkhead of the chain locker is plywood but is faced on the chain locker side with glass fibre to make a waterproof chain locker compartment. The windlass is mounted on a glass fibre reinforced plywood shelf with the power cables coming in through a hole in the chain locker aft bulkhead just below that shelf. That shelf has now been further reinforced by me with a stainless steel plate.
Between the aft bulkhead of the chain locker and the forward bulkhead of the fore cabin there is a narrow void space with the windlass cables passing through that forward bulkhead in an area hidden from view by a series of cupboards on the starboard side. The void space is essentially a dry area, and the hole through the aft chain locker bulkhead for the power cables is sealed with some form of mastic/sealant.
The forward bulkhead of the fore cabin consist of two pieces of thin plywood that extend from the inside of the hull port and starboard and from the top of the bunk base upwards to the deckhead, and meet together in a vertical join on the centre line and which are covered with a foam lined plastic or leatherette similar to the headlining in the main cabin. That forward bulkhead in the fore cabin is not a structural or strength member, merely a lightweight division.
Whether your B31 is similarly constructed I don’t know, but it is possible that your 31 and my 36 may have similar construction features.

[sunshine]

My Bav 30 had a cackhanded aftermarket windlass installed, and the bulkhead similarly rotted from repeated water ingress.  I dried it out over a period with a heat gun, making sure it was genuinely dry before repeatedly soaked it with wet rot repairer. This firmed up the soggy sections satisfactorily. Then just seal up the initial leak. I used domestic ronseal wet rot repairer, intended for roof joists in a leaky roof. I considered cutting out the rotten ply if this hadn't worked, but it didn't come to this. I might have some pics if it would help.

[hennypenny]

Thanks all that is helpful. Any pictures you have of repairs would be gratefully recieved!
Also how is it best to seal the cable? I was thinking of putting in a deck gland, would that work? At the moment it looks like they drilled a hole and then just put a lid of glue in there and that has clearly not worked!

[sunshine]

For the hole where the cable goes through, you need to seal the ply around the inside surface to prevent water soaking the ply again. If this was a hole in the deck, you would use gelcoat, so I'd probably do the same here, although some regular sealant would be cheaper. I might try a grommet from an electrical supplier rather than a full-on deck gland given the cost considerations, but yeah a deck gland should work. These are the best pics I have. They are 30 rather than 31, taken from inside the cabin. Don't be shy about taking the interior panels off. The panel inside the bulkhead has two star/torx screws through from the anchor locker that go into the end of the shelf (one per shelf). Once unscrews you can slide the panel up and bend it so it runs along the ceiling to get it out. If you bend it too far it snaps. I replaced mine with a new sheet of ply covered in leatherette from an upholstery store. The rotten part of the ply was the darker sections at top, especially at the left. They were soaked and spongy. Once dried out and soaked with wet rot repairer they were fine.