Another Moment of Truth

An anxious time came and went yesterday as my friend Major and I moved the new top project into its next phase. At issue was whether the scarf-jointed structure I had built of 3/8-inch marine plywood, epoxy resin and PVC molding would bend -- or break.

The suspense began with assembly of a strongback on the bench. I had pre-fabricated the structure a few weeks ago and piled the pieces under the bench. We put it together with 3-inch deck screws in a half-hour or so.

The idea is to approximate the curvature of the supporting structure we built for the top on the boat last November and December. The strongback has five curved "rafters". These are screwed onto a box made of eight-foot 2x10s and 2x4s. There is one longitudinal stretcher to help hold it together. The whole thing is screwed to the tabletop.

Items of faith

There are two items of faith in play at this point. The first is that the top will bend (non destructively). The second is that the bent top will hold its curvature after the epoxy resin and fiberglass fabric coating  is cured and the fasteners are removed.

The first concern was resolved shortly after we brought the top to the strongback and started fastening it in place with my specially modified 1 5/8-inch drywall screws.

The top bent! No complaints from the materials. Nothing broke.

We used nylon "load binder" ratchet straps to ease the top curvature into conformation with the rafter curves.

In a trice, I sprang cat-like onto the top and began applying my special fasteners.

The ratchet straps were released one at a time as we completed screwing the top down to each rafter.

Here's one of the special fasteners. It is a standard  1 5/8-inch drywall screw with a snippet of nylon ice maker water tubing slipped over the last half-inch of threads before the head.

Very soon, we will be applying fiberglass fabric and resin to the top surface. The nylon collars on the screws will keep the screw heads above the  fabric and resin. The resin won't stick to the nylon, so the screws  and collars should be easy to remove after the top is glassed.

Yet to come --

I mentioned two items of faith at the start of this post. The second, not yet revealed, moment of truth will come when the glassed top has cured, and the screws have been removed. Will the top hold its shape? Stay tuned.

Meanwhile, here's what the top looked like at the end of  work yesterday.

Click to enlarge and you may be able to see the rows of fasteners in the top. I think they look like miniature versions of those electrodes sticking out the sides of Frankenstein's neck.

When removed, the fasteners will leave 26 holes in the fiberglass fabric, which I will patch before I paint the top.

Tomorrow, I will lay the fiberglass fabric out on top of the top so the fabric weave can relax and wrinkles can fall out. I think I will have to cut little slots in the fabric to slip over each screw head, but some other solution may come to me before I start on that part of the work.

Finally, please keep it up ... I really enjoy the conversations that can develop in the comments sections after these posts. I value your ideas and I will answer questions promptly.