Stem

Justine’s stem has a significant curve, and the construction plan shows it as a single piece. In order to have sufficient strength, the grain of the plank from which the stem is cut must align with the stem’s curved shape. So I was in search of a plank cut from a log with a significant bend. In boatbuilding parlance, this is known as a “grown shape.”

Some tree species have lots of branches that are naturally curved. Live oak is a good example. Massive frames for ships like Old Ironsides were cut to shape from live oak branches rather than be shaped by steam bending.

In New England nowadays the most prevalent species from which to seek grown shapes is black locust. I knew that New England Naval Timbers had a good supply of black locust, so I made a plywood pattern of the stem shape and took it with me in my quest for a suitable plank. Scot accompanied me on the trip and we spent the better part of a day inspecting stacks of planks from which I could make not only the stem, but also the frames and keel plank.

We started the search for the stem plank by picking over a very large pile of black locust planks. There were all sorts of shapes, consistent with the naturally curved growth habit of this species. Because of the odd assortment of shapes, the planks could not be neatly stacked. So we spent a good bit of time and energy digging through a sizable pile of very heavy planks. Each one that looked like it might work, failed to conform to the pattern.

Fortunately on the day of our visit, a fresh supply of black locust logs had arrived and was in the process of being cut into planks. Duke Besozzi, New England Naval Timbers’ proprietor,  took a look at the pattern, and the pile of logs, and identified one he thought might work and put it through the mill. Voila! I had the plank I needed.

Black locust plank with stem pattern overlaid. The direction of the grain in the curved part of the plank closely matches the shape of the stem.
I made the first cut with my circular saw, cutting slowly so the saw would not bind in the curved cut. The plank was about 2 1/2″ thick, and the capacity of my saw was only 2″, so the cut did not go completely through the plank.
Using a tip from Scot, I drilled a series of holes at about 3″ intervals, down through the kerf of my first saw cut and out the far side of the plank. When the plank was flipped over, I had a nice line of holes to guide a second cut that would meet up with the first one and free the two pieces.
First rough cut of the stem blank is completed. The stem will come from the crescent-shaped piece.
My first cuts were deliberately oversize. I ran the stem blank through the planer and reduced the thickness to 2″, then let the blank age in the barn for several months before proceeding In this way, any distortions during drying could be corrected when the stem was planed to its final 1 3/4″ thickness and cut to its designed profile. The ends of the blank were given a coat of red lead to retard rapid drying and prevent checking (formation of longitudinal cracks that might start from the ends).
The stem cut to its final profile and thickness in place on the construction molds. The bevels on the floors at stations 2–5 match the changing inclination of the stem. A batten is temporarily fastened along the position where planking will be. Plank ends will land in a groove that is cut in the stem, known as the stem rabbet.
The stem rabbet is a “V” shaped channel that provides a landing place for the forward ends of the planking. The position of the rabbet  is indicated on the lofting. I cut most of the rabbet with chisels. The wood block seen resting in the rabbet is in position where a plank will terminate and be fastened to the stem. The two facets of the rabbet are cut to meet at a right angle, and the forward most facet is 5/8″ wide, matching the planking thickness.
The stem has been trimmed to its final profile, the stem rabbet has been cut, and the contacting surfaces between the stem and the floors have gotten a coat of red lead. The stem is ready to be bolted to the floors at stations 2 and 3. The keel plank will overlap the stem at stations 4 and 5.