Replacing Rotten Bulkheads

Aside from the cockpit sole repair, the next biggest project in the engine room area is to replace the bulkhead separating the engine room from the galley.  The most extensive damage done to Windsong, thanks to years of leaks and neglect, was the deterioration of anything made of plywood on the port side.  All cabinets, bulkheads, floorboards, etc that were in the path of the leaks on the port side of the boat were rotten away and need replacement.  At least the teak trim held steady.  The problem was evident when I bought the boat, but the extent of it was only uncovered after taking most of it apart. The first bulkhead to be replaced is the port bulkhead between the galley and engine room.  I wasn't planning on replacing this one, even after taking most of the boat apart.  It seemed to be in mostly decent condition, with the exception of the port most side that is hidden behind cabinetry anyways.  When I finally took apart the refrigerator that was mounted on the rear of the bulkhead, I found much more damage and decided it needed to be replaced with the rest of them.

Before taking anything apart

Post demolition, damage exposed

From the engine room:

First up was to remove the existing bulkhead, trying to keep it from falling apart so I could use it as a template.  Here is the engine room exposed without the bulkhead:

I spent a lot of time figuring out what kind of plywood I need to use for the bulkheads.  I studied all of my books, forums and google searches.  Not to my surprise at all, there were dozens of differing opinions on whats best and whats worst.  Eventually, I resigned to buying expensive marine grade plywood, and as soon as I was ready to start the project I went up to the lumber yard to buy a plank of the stuff.  The staff were kind enough to recommend that I use a different grade of plywood, half the price of the marine stuff.  Marine and the alternate used the exact same wood and glue, the only difference was the facing grade and the possibility of small gaps in the glued plys.  I planned on sealing the entire bulkhead in a few layers of epoxy, particularly thick on the edges; and after explaining this they said it was a waste to pay twice the price for the marine stuff.  Marine ply has its uses, and I will be getting some for the hull of my dinghy, but the bulkheads should be fine with the stuff I got.  It wasn't cheap, definitely more expensive than anything at Home Depot, but not nearly the price of marine ply.

Here is the new bulkhead already cut out.  I used an electric jig saw and taced the lines using the old bulkhead.  It needed a bit of trimming to fit properly, but I eventually had a good dry fit.

I spent the next few days applying two layers of clear epoxy to seal the piece (4 layers on the edges).  It was tough sanding the stuff perfectly flat, so it took longer than I expected.  Since this plywood was a lower grade, one side is not a smooth surface with a few knots.  It didn't really matter as that side will be in the engine room and covered with insulation.  The higher quality side will be primed and painted to match the rest of the interior.  I spent more time making sure the galley side was flat and flawless.

Final epoxy coat on:

I sanded the entire surface once more after the final coat of epoxy.  Before fitting it into place, I glued a strip of closed-cell foam on the top edge of the bulkhead.  The reason for this is so no hard spots develop on the deck due to compression on the bulkhead.  I had a hard time finding the foam, so I just cut up a piece of foam pipe insulation that was made of the same stuff.  Next I put the bulkhead in place, drilled holes and screwed it into place.  The holes were counter-sunk so I can plug them with bungs if I choose.  I won't bother with bungs on the engine room side, but probably will on the galley side.

With the bulkhead in place, I then tabbed it to the cabin top with fiberglass and epoxy.  Trim will hide the fiberglass tabs once everything is finished. I made sure the cabin top was sanded and cleaned, following basic epoxy procedures.  I first made filets of thickened epoxy on each side:

Then a couple layers of fiberglass:

Fiberglass cured and sanded:

With that, the bulkhead replacement was finished!  As I mentioned before, the engine room side will have sound insulation glued to it, and the galley side will be primed and painted with the rest of the cabin.

Engine room side:

I feel good about this repair, especially to finally have tried and completed a big one I have been nervous about.  A few more bulkheads to go, but those will be easy as I know what I'm doing now.

Skill gains: +3 carpentry +2 fiberglass & epoxy