Lazarette Modifications, Part 4: Tabbing for the Bulkheads

Tabbing for the Starboard Bulkhead in the Lazarette

Having constructed and epoxy-coated the necessary cleats and shelves for the planned lazarette modifications on Oystercatcher, my Ericson 25, I was now close to being able to install these components, but before I could do any of this work I first had to ensure that the port and starboard bulkheads were securely attached to the hull. These bulkheads, after all, had to support two separate shelves, one for the fenders and the other for the reserve battery bank. The latter, on account of the weight that it would be supporting, was especially important. 

While the tabbing of the bulkheads to the hull is the subject of this fourth part of my eight-part article, let us begin with a brief digression on some of the initial grinding and dry-fitting of the components that I undertook prior to my work on the bulkheads. This digression will serve to remind everyone of the scope of this project and the relationship of the port and starboard shelves to the other components that I would be adding to the lazarette.

Near the end of part three I described how I removed the old port and starboard water tank cleats from the hull, and I described how I had constructed new, full-length cleats out of Douglas fir to replace them. Below we see one of the new cleats dry-fitted into place.
One thing I wanted to do before calling this little sub-project complete was to remove the remnants of the fiberglass mat that had held the old cleats in place.
My angle grinder easily removed this matting and left the surface in a much more attractive condition.
Now I thought it would be a good idea to dry-fit the new water tank. Although it was identical in size to the old one, I nevertheless wanted to use it as the basis of my measurements and calculations in terms of the reference lines I was drawing on the hull with my black Sharpie marker.
After I had dry-fit the new cleats on either side of the water tank, I grabbed the two shelves that I had earlier constructed and epoxy-coated. I wanted to see how they looked, and I wanted to reassure myself that they fit well in this space. It was good that I took the time to do this dry-fit, because it turned out that I had neglected to account for one of the ports on the water tank when I had constructed the shelves. If you look at the picture above, you'll see three ports, each temporarily stuffed with paper towels to keep out debris. The large port on the left is the inlet; the port on the bottom is the outlet; and the port in the background is the vent. As you can see in the picture below, I had neglected to account for the vent when I had constructed the aft shelf.
My easy, yet unavoidably inelegant solution to the problem was to drill a hole in the appropriate location with a small hole-saw.
That did it.
With those minor problems out of the way, I now had a blank canvas before me. The easiest thing to have done would have been to have started my installation of the components in the center of the lazarette. In other words, I really wanted to start with the battery bank shelf. It was going to sit right there, front and center, between the water tank and the opening to the lazarette. Starting with the battery bank shelf, though, would not have been that smart, would it? After all, I needed to be able to climb into the lazarette to work, and that battery bank shelf would have made that more difficult. Therefore, after thinking through these different points, I decided that the best place to start was with the bulkheads, the pieces of plywood you see on either side of this picture. These, as I said above, presented some problems. They were not secured to the hull, and they really needed to be, since since they would be supporting the shelves that I would soon be installing on the port and starboard sides.
I needed to start with one of the bulkheads, and I chose the starboard one, because it presented more challenges than the other. Why not just tackle the tougher of the two first? That was my thinking. So what made this bulkhead a headache? Well, first of all, whoever installed the thing at the Ericson yard in Southern California in 1975 installed it too close to the hull. In some spots it was touching the hull, and in other spots it was too close for comfort. As you probably know, bulkheads should not come into contact with the hull, since the stiff edge of the wood can damage the hull as the hull slightly flexes while underway. You might be saying to yourself, "well, yes, but this is not really a bulkhead, but simply a partition between the icebox and the lazarette." To this, I would say, "even if it is a partition, it should not be in contact with the hull." I must add, though, that I'm not entirely sure that it was meant to serve only as a partition. I base this statement on the installation of the bulkhead on the port side, and installation that we will soon examine below. For now, though, we must focus on the issue at hand, and that issue is that this piece of plywood had to be secured to the hull in a fashion that would provide some protection to the hull.
The first thing I needed to do was to grind away some of the paint from the bottom edge of the bulkhead. The fiberglass that I intended to install as tabbing needed to have a fresh surface to which the epoxy could adhere.
Before I could complete this grinding job, I needed to cut away those parts of the bulkhead that were too close to the hull. The only tool that allowed me to do this was an oscillating tool, also known as a multi-tool. For this, I used my Rockwell Sonicrafter X2 with a saw-blade attachment. The Rockwell in general would provide invaluable service during much of this lazarette project, especially when it came to sanding in tight areas.
For the sake of consistency, I made the cut to allow for 1/2 inch of space between the bulkhead and the hull.
The higher up I went, the more difficult it became. This required a lot of concentration. The last thing I wanted to do was damage the hull. That would not have been a good scene - damage the hull while trying to protect the hull.

The bulkhead as it appeared at the end of the cutting.
Next, I needed to remove as much of that gray paint as possible from the hull so the epoxy could grab and hold that hull with tenacity. The 50 grit sanding pad was not sufficient for this job. I said that the Rockwell did a great job on this lazarette project when it came to sanding. It did, when sanding cured epoxy in tight areas. It wasn't very good when it came to getting that gray paint off the hull.
The grinder was the best tool for that job. The grinder also served me well on the bulkhead. I had to be especially careful, since the 36 grit disc could have easily cut into the hull, if I had allowed it to slip off of the bulkhead.

For those spots on the bulkhead that were just too close to the hull, I fell back on the Rockwell.
I also used the Rockwell in the tight spot on the forward side of the bulkhead. I planned to put a little bit of tabbing on this side, since part of it was accessible. Most of it was obstructed by the icebox.
When I had completed all of the sanding and grinding, I grabbed a pair of blue nitrile gloves and my solvent of choice - toluene. This stuff is stronger than acetone, and I wanted to make sure that I removed as much residue and as many contaminants as possible in preparation for the application of the epoxy. Toluene is what they used to use for fingernail polish remover, back before they realized that it's not something you want on your skin, especially repeatedly, over a long period of time.
The toluene cleaned up the work area very nicely. I should note that I almost always wear a respirator when I break out the toluene.

You might have noticed in the picture of the blue nitrile gloves and the toluene that there was a can of Great Stuff spray foam. I had used many a can of this stuff to seal cracks and holes around my house during a lengthy renovation project, and I had heard from some boat guys in Charleston that this product could also be used in conjunction with epoxy when dealing with various gaps on the interior of a boat. They said it could be shaped with a knife and then covered with epoxy and cloth. My plan was to spray a bead of foam between the bulkhead and the hull. This would, when cured and covered with epoxy and cloth, provide some cushion for the bulkhead. Fortunately for me, the can that I grabbed for this project had been sitting around in my work shed for quite some time, and when I went to spray it along the bulkhead, the nozzle-head assembly snapped off. At that time, this was highly irritating to me. It was even more irritating to me, when I grabbed the second can from my work shed, climbed back up into the boat, down inside the boat, and into the lazarette, and then had the exact same thing happen. Frustrated, and needing a break, I went inside and starting Googling around. First of all, I discovered that this this nozzle-head problem is widespread, especially if the can has sat on the shelf for some time. Secondly, I discovered that quite a few boat owners had been displeased with their application of Great Stuff in their boats. Apparently, it has the propensity to hold water, and this is never good on a boat. Taking my misfortune with the nozzle-heads as a stroke of good luck, I turned my attention to alternatives.
There are various rigid, or I should say semi-rigid foam products on the market. Don Casey, in the second edition of his helpful and humorous tome, This Old Boat, urges his readers to place a strip of polyurethane foam between the bulkhead and the hull. I had considered following his advice before I had ever considered using the Great Stuff spray foam. The only problem was that I could not find any sheets or pieces of polyurethane foam locally available. I did find it available online from places like Defender, but I wasn't up for paying the shipping. There just had to be some alternative. I had briefly considered using polystyrene foam insulation that was readily available at Lowe's, but I was a little concerned about how it might react in the presence of epoxy. Now I looked in earnest at this polystyrene as an alternative, and I spent a good bit of time Googling around, reading everything I could about the subject of polystyrene and epoxy. What I discovered was this: there are two types of polystyrene board EPS (Expanded Polystyrene) and XEPS (Extruded Expanded Polystyrene). To make things more simple, many people often shorten the name XEPS to XPS. At any rate, EPS is bead-like in appearance. This is the stuff that cheap coolers are made of. It's also the stuff that many surfboard manufacturers used for a long time, although many have now moved away from it for various reasons, one of which is its toxicity. XPS, on the other hand, is smooth in appearance and less harmful to the environment. This is what different companies use for foam-board insulation. It is more water resistant than EPS, and most importantly, it will accept epoxy. Having learned all this, I took a trip out to Lowe's and saved myself a lot of money by opting for XPS in place of polyurethane foam from Defender.
Back at home, I cut myself a two inch strip.
After I had completed the cut, I made sure to remove the protective plastic coating that the manufacturer had applied to the foam, apparently to help prevent damage to it during the shipping and handling of the product.
Next, I dry-fit the foam and applied epoxy to hold it in place.
Concurrently, I cut strips of 6 ounce fiberglass tape that I would soon lay down after I had applied the appropriate fillets. Notice that there are two sets of fiberglass tape. One is for the bulkhead on the port side. I will address this in a moment.
I used RAKA epoxy with colloidal silica as a thickening agent.
Due to the width of the foam strip, I had to lay down two different fillets - one against the bulkhead, and one against the hull. By the time I was finished, I had one large fillet. Note that prior to laying down the fillets I soaked the plywood and the hull with neat epoxy.
I then mixed up 3 ounces of epoxy and applied the two pieces of fiberglass cloth. A little while later, I would come back with some epoxy, slightly thickened, to fill in the weave.
At the same time I did all of this, I also applied cloth to the other side of the bulkhead, at least the eight inches or so of it that was accessible to me. The icebox obstructed the rest of it.
At the same time that I had been working on the starboard bulkhead, I had also been working on the other one. Here's what it looked like before I ever did any grinding. You'll see that someone at the Ericson yard had deliberately not painted the bottom part of the bulkhead. The reason? This was where the tabbing was supposed to go. Do you see any tabbing, though, other than the piece up near the top of the bulkhead? I don't. Looks like a worker got this one past the yard manager's attention.
I didn't think that the existing exposed plywood provided enough room for the fiberglass tape that I planned to lay down, so I ground off a couple of inches worth of paint.
I also took the paint off the hull, just as I had done on the other side.
This bulkhead had been thoroughly tabbed on its forward side. This forward side does double duty, insofar as it is a part of the cabinet for pots and pans underneath the stove. You might be able to tell that this bulkhead is spaced about a 1/2 inch from the hull. The tabbing on the galley side is what keeps it from coming into contact with the hull. In other words, there is no foam barrier; there is simply space. I believe this was the norm at the time the boat was manufactured.
Since the addition of foam was not an option for me, I decided to follow the original foam-less method of tabbing by applying tape directly to the hull and bulkhead. In preparation for this work, I cleaned up the area with toluene, and then I wet it down with epoxy.
I thought it looked pretty good after I had gotten the two layers of tape in place. You might have noticed the clamp in the picture below. There is a layer of fiberglass around the companionway. There was a small gap between the bulkhead and the fiberglass. In order to close this gap permanently, I dabbed a little epoxy in the gap and then clamped the two pieces together. This ensured that they would now be as one, and it ended up making for a more solid structure.
Below is a good sign of a completed sub-project within the lazarette. Throughout the project, I would, during the many sub-projects, throw everything related to toluene and epoxy over the side of the boat. The mixing cups and plastic stirrers I would reuse the next day. Everything else was trash.
This ends the fourth part of my eight part article on the modifications that I made to Oystercatcher, my Ericson 25.