On initial inspection of the boat, it seemed clear that the mast beam would likely need repair or replacement. This initial reaction was supported by the survey results. There is a clear inward bulge in the center of the overhead and there is also clear evidence of movement of the mast beam, especially on the forward face of the bulkhead and along the doorway trim. Additionally, all of the tabbing has broken loose from the beam. Discussion on the Triton e-mail list revealed that many boats do not have any tabbing between the mast beam and the bulkhead and overhead, suggesting that perhaps someone had attempted an ineffectual repair or "upgrade" at some point in the past.

Initial Inspection

Last fall (2001) I removed the mast step and all of the bolts holding the mast beam in place through the bulkhead. I had a bit of trouble with this, since the bolt heads had been glassed over on the forward face of the bulkhead, so I had to grind through the glass in order to remove them. At this point, the beam was loose, and I was able to remove the sister plate, however the main beam was still loosely held in place by the tabbing. No problem. Using my 4-inch grinder, I cut away as much tabbing as possible. Unfortunately, this still left enough tabbing to prevent the removal of the beam, and my grinder was too large and awkward grind away what remained.

Fortunately, I was able to get a Dremel tool on loan from Tim Lackey, and spent almost 2 hours grinding/cutting away the remains of the tabbing. The Dremel was small enough to get into the tight spaces, but unfortunately just doesn't cut very quickly! Eventually I was successful, and the beam slid out with only slight coaxing with a pry bar.

Once I got the beam off of the boat, it became clear that removal, rather than repair and strengthening, was the correct choice. Besides the hole that was drilled through the beam as a conduit for wiring, the beam has 2 checks, about 14 inches long running lengthwise along the beam. These checks were not visible until the beam was removed.

One interesting thing I discovered, though, was that the "bulging" of the overhead that we had noticed, and assumed was due to deck compression, actually appears to be part of the original layup. The mast beam and the bulkhead are actually shaped to accommodate this bulge. This discovery is somewhat relieving, actually! However, at this point, I am undecided as to whether to try to shape the beam to fit back up there (several hours with a plane and belt sander), or if I will attempt to fair the curve of the overhead by laying in additional glass (several hours of cussing at glass and epoxy over my head). More on that when I head out to the boat with the beam.

A New Beam Takes Shape

My original plan for a new beam was simply to cut the shape of the beam from marine plywood, and laminate those together. This would have been simple, and probably sufficient. However, when I was at the "Triton Factory" in Rhode Island this spring, I was bewitched by Dana Berube's beautiful laminated oak beam. I had to have one. Simple as that! Time for a modification of the plan.

My new beam is built up from laminated Ash strips. I secured the assitance, and use of space, of a family friend who has a cabinetmaking shop. I picked up about 18 board feet of 4/4 ash from a local dealer and headed over to the shop. I purchased substantially more wood than I anticipated needing, to allow for selection of undamaged strips for the lamination. I ended up using only about 1/2 of the wood that I bought, but better safe than sorry. Plus, ash is cheap.

The first step was to joint one edge of the boards, which were about 7 inches wide by 10 feet long. The boards were a bit cupped, so I ripped them to 3 1/2 inches wide before running them through the planer. Although the wood was nominally 4/4, it actually was closer to 5/4, so even after planing, the boards were just hair under 1 inch thick. With a bandsaw, we resawed each board into two, then sent them all through the drum sander with 40 grit paper to remove the resawing blade marks, and to provide some tooth for the epoxy. The final thickness of the laminate layers was about 3/8 inch. I cut the boards to 5 foot lengths, and we were ready to start the lamination.

Lamination begins

This was the first time I had ever done anything like this, so I was not exactly sure how smoothly things would go. The first step was to wet out the strips with unthickened epoxy. I then mixed up another batch of epoxy, thickened with high density adhesive filler. Working quickly, we applied a coat of the thickened epoxy to one side of each strip.

Now it was time to put the layers together and see if they really would bend to the form. I had prepared the form ahead of time. I built up the form from two 2x4s which I had cut with a jigsaw to match the curve of the original beam. We stacked the boards, making sure that one of the faces with thickened epoxy would mate with a face that was just wet out, thereby assuring that there would be a layer of thickened epoxy for every joint. Once the stack of boards was centered on the form, I applied the first clamp. At this point, all hell broke loose, as the clamping pressure, which was being applied with a bar clamp from one side, caused the boards to slide apart, widthwise. After a moment of panic, I realized that we could simply slap a board on either side of the beam and apply clamping pressure to keep the layers in line. After we had a couple of clamps in position, we were able to remove those boards, allowing us to apply more clamps.

One thing learned: you can never have too many clamps when laminating! Assess your clamp inventory before beginning. If you think you have enough, buy more. Then get a couple of extras for good measure! Clamping was really pretty simple. We started in the center, and worked towards the ends, applying clamps every 8 to 10 inches or so. Apply a clamp, tighten it as much as possible, the apply another clamp, from the opposite side of the form, and tighten it as much as possible, then go back to the previous clamps and tighten them a bit more. We kept working like that until the new beam was bent to the form. The whole process, from beginning to wet out the boards, through to the finish took about 20 minutes. Other than the initial trouble of keeping the laminate layers from sliding around, everything went very smoothly.

The new beam measures about 3 1/4 inches wide by 4 1/8 inches thick. A real improvement over the original beam which was not quite 2 by 3 inches.

A Few additional steps

A couple of days later, I headed back to the shop to take the original beam off the form, and to laminate a sister plate. When we pulled the clamps off the beam we discovered two things. First: springback was minimal. Perhaps 1/8 inch over the 5 foot span of the beam. Second: laminating a beam leads to LOTS of squeeze out, and squeeze out doesn't mix too well with bar clamps. Well, actually, it mixes TOO well. Don and I spent about 45 minutes taking clamps apart and chiseling/filing epoxy out of the various parts to return the clamps to working order... live and learn. A couple of passes over the jointer, and a few minutes with a belt sander cleaned the beam up nicely.

We laminated up a sister plate, following an identical procedure. With the experience of the first beam under our belts, things went quickly and without nearly as much stress. Hardly even worth mentioning, except that this time we wrapped the beam in wax paper to keep the squeeze out off of the clamps. The new sister plate is also about 3 1/4 inches wide, but only about 2 1/2 inches thick.

Test-fit before installing

Update 2/26/2002: The next step was to take the beam out to the boat and dry fit it. Since the beam is larger than the old one, I had to cut about half an inch or so off of the compression posts. I thought I would be able to remove the posts, install the beam, and then reinstall shorter posts. No Way! The screws holding the compression posts in place were not coming out, short of drilling them out. So, instead, I cut the posts in place with a hand saw.

Then, I rough cut the beam to the correct size, based on the old beam. Then, by taking the beam out to the boat and test fitting it, I was able to determine where more material needed to be removed. This was done using a power hand planer, which worked quite well. In fact, it worked almost too well, as once I got the beam fit back against the bulkhead, I found that I had actually removed a bit too much material on the outboard ends of the beam. So, there is a gap of about 3/16 of an inch or so at each end. Essentially the problem was that I didn't leave enough of a bevel on the ends to accomodate the curve of the coachroof. As such, the beam is the right size where it is in contact withthe bulkhead, but a bit short on the visible face. This is a cosmetic problem rather than a structural one, since the real job of the beam is to transfer the force of the mast compression to the compression posts on either side of the doorway leading to the v-berth. I should have made 2 templates when I was shaping the beam, rather than using the old beam as a template, since I made the new beam larger in all dimensions. Live and learn....

Next I put the new beam in place and marked the opening of the doorway on the beam. I took the beam back into the shop and transferred those markings onto the sister plate. I cut the sister plate to length and installed it with epoxy. I toyed with the idea of also using screws, as was done with the orignal, but decided against it. I don't expect to see any movement, but I'll keep an eye on the whole thing this season.

The final step before installing the beam was to round off the edges that will be exposed to head-knocking, which I did with a palm sander. Also, since the beam will be installed with epoxy, I sanded all of the bonding surfaces with 40 grit paper to provide some additional tooth for the epoxy bonds. The beam is now just waiting for installation on the boat.