Caledonia Yawl Construction
Part I: Building Frame, Moulds, Inner Stems, and Keelson
(click on images to enlarge)
The building frame or strongback is typically made of wood. This building frame was made of welded 2" x 4" tubular steel left over from the construction of a metal "sculpture studio" roof. (This studio just happens to accommodate the Caledonia Yawl!) Mic and Ken
Spreaders or spalls made of 2 x 2's are attached at the bottom of each mould. The spreaders are fastened to the steel building frame with self-tapping screws. Initially, all moulds are lifted a fixed small amount above the building frame with wooden spacers or shims. Mould Alignment Steel rules clamped to the moulds are used to check alignment. The wooden shims between the spreaders and the building frame are changed in thickness as needed to rotate or lift the moulds into proper alignment. Stem-Shaping Blocks Fastened to Table Wooden blocks define the curves in the stems. Clear packaging tape is used to keep the stems from being glued to the blocks and table. Mic Checking Clamps on Just-Glued Laminated Stems Strips of southern yellow pine, 2" x 1/4" in cross section, are ripped from 12" x 1 1/2" x 20' boards using a circular saw and a carefully designed jig. The inner stems are laminated first. After the epoxy from this lamination is cured, the outer stem laminations are glued together and clamped against the inner stems. Foreward Inner Stem The stems are attached to the moulds and building frame first. Aft Inner Stem and Keelson The keelson begins as a 13' x 4" x 1" piece of yellow pine. A slot for the centreboard is cut, and then this piece is glued to the stems using clamps to force its slight curvature. Forward Inner Stem and Keelson,
Brackets, screws, nuts, and bolts are used to hold the backbone firm against the moulds and maintain the curvature of the keelson while the hull is being planked. Forward Inner Stem and Keelson,
Stems and kelson are rough shaped with a hand saw and chisel and then faired with a block plane.
Aft Inner Stem and Keelson,
A 2 x 4 spacer between moulds, rather than a 2 x 2, is needed to hold down the aft end of the keelson. Aft Inner Stem and Keelson,
The centerboard slot and the curvature in the aft end of the keelson can be seen in this picture. Aft Inner Stem and Keelson,
The foreward end of the aft inner stem is shaped according to the plans.
Caledonia Yawl Page Ken Leap's Main Page