Breasthook and Deckbeams

Breasthook

The breasthook adds rigidity to Justine‘s structural elements near the stem head where the sheer clamps and sheerstrakes are attached. It has a triangular shape and lies atop the sheer clamps and against the stem and sheerstrakes.

The sheerstrakes and sheer clamps are fastened to the stem, but the joints would not be very rigid without a structural member that further secures them. That’s the job of the breasthook.

I used off-cuts from the black locust plank I’d purchased for Justine‘s stem to make up a blank for the breasthook. I ended up edge-gluing six pieces, and inserting two 1/4″ bronze drifts into the blank for some extra reinforcement of the glued joints (and with forethought to where future fasteners would need to go). I made a plywood template of the space the breasthook would occupy and began to bring the blank to its final shape.

I glued up six pieces of black locust as a blank from which to make Justine’s breasthook.

I planed a small amount off the sheer clamps so that the breasthook would lie flat against them, then cut the bevel required for a tight fit against the stem. I then used my block plane to plane the winding bevels on the end-grain surfaces that would contact the sheerstrakes. Some patience is required to get all the bevels to fit simultaneously.

The front of the breasthook is bevelled to fit snugly against the stem, and the sides require a winding bevel to match the inside surfaces of the sheerstrakes.

Once the breasthook was fitted, I gave the underside and bevelled surfaces a coat of red lead, drilled for the fasteners, and spread 3M 5200 on the mating surfaces prior to driving all the fasteners. Finally, I planed a very slight crown on the top of the breasthook to match the curvature of the deck beam mold.

I fastened the breasthook with two fasteners into each sheer clamp, one into the stem, and two driven from the outer surface of each sheerstrake.
Afterdeck beams

Justine has a foredeck and a small afterdeck, both made of 9 mm marine plywood. Both decks are supported by white oak deck beams that run athwartship. I decided I’d tackle constructing the smaller afterdeck first because it would be easier and thus a good learning opportunity.

In the Flatfish and Fish Class designs, the afterdeck height lies about halfway between the cockpit seats and the top of the cockpit coaming. The afterdeck is supported by three deck beams, and the deck beams rest on cleats that are attached to the frames between stations 21–23. It’s not obvious from the plans, but these cleats need to have a significant twist, and some curvature, to fit properly against the frames. I made a jig so that I could steam the cleat blanks, then twist them into the correct shape and clamp them in the jig to cool.

To impart the significant twist in the cleats that support the afterdeck beams I made a jig and proceeded to steam them and clamp them into the jig.
I steamed the cleat blanks in a tube made of polyethylene sheet, then twisted them and placed them into the bending jig I’d made.

The afterdeck beams are white oak, cut to the afterdeck curvature specified in the plans.

The cleats that suport the afterdeck beams have been fastened to the frames and the first of three deck beams placed in position. The ends of the deck beams rest on the cleats and  are fastened to the frames with screws.
All three afterdeck beams are in place, and they’ve been painted on all but their upper surfaces. When I lay the afterdeck, I’ll use 3M 5200 where the plywood deck is fastened to the deck beams. Note that the temporary 2 x 4 backing the hull at station 21 has been removed, as the deck beams now maintain the correct beam well aft in the hull. I also used a piece of white oak to made a support to fasten the rear edge of the afterdeck back at the transom.
Foredeck beams

Justine‘s foredeck extends from the stem back to the forward bulkhead of the cockpit. Forward of the cuddy top, the deck beams are continuous from port to starboard. The deck beams are interrupted by the cuddy top, so from stations 10–12 they are half-beams that extend from the shearstrakes to the cuddy coaming on each side of the hull. In this post I’ll just illustrate the installation of the full deck beams up to the forward cuddy bulkhead (from stations 2–8).

Station 2’s deck beam is in place and ready to rivet to the sheer clamp. Once the deck beam was in position, I removed the temporary 2 x 4 that maintained the hull’s designed beam at station 2.

The forward deck beams are fastened with #8 copper nail rivets that pass upwards through the sheer clamps and deck beams. Copper burrs go on the nails protruding from the deck beams, the nails get trimmed to the proper length, and rivet heads are peened atop the burrs.

I made all of the foredeck beams to the curvature of the deck beam mold. Here I’ve got the deck beams ready to rivet in place at stations 2–8, and all but one of the temporary 2 x 4’s are removed from the hull.