Download the entire report in Buttresses and Bilge Boards
The mainmast step is supported laterally by buttresses, four of which were uncovered on the port side of the keelson. The buttresses were intended to brace the step, preventing its movement athwartships as the ship sailed on various tacks, or rolled from side to side. Three removable bilge boards are let into the spaces between the buttresses to protect this area from trash that might clog the bilge, and subsequently the pump. Timbers partially visible on the unexcavated starboard side of the keelson revealed the same arrangement as the port side. A similar number of buttresses and bilge boards were found on San Juan (Stevens 1983:7, Fig. 1) while the Highborn Cay Wreck mast step was supported by only three buttresses per side (Smith 1993: 68-69. Figs. 3.7, 3.8). The thicker end of each buttress rests against the mast step, while the outboard end butts up to a ceiling plank. Each timber is toe‑nailed in place to the mast step and fastened to the floor at the opposite end with square-shanked iron spikes. The outboard ends of the buttresses are let into the adjacent ceiling plank, which has been sawn with 7.5 cm-deep cutouts to accept them, thus preventing the assembly from shifting under stress.
Buttresses are 63 cm in length, and taper in molded height from approximately 25 cm at the mast step to 6.5 cm at the ceiling. Sided thicknesses are 11.5 cm for the first or forwardmost buttress, 12.5 cm for the second, and 17 cm for the last two. An adze mark 8 cm in length and parallel to the keelson was noted on the second buttress. Rabbets (grooves), approximately 2.5 cm in depth and between 3 cm to 4.5 cm width, were cut on the interior and upper edge of each buttress to allow bilge boards to fit between, and even with the tops of, the four timbers.
Lying between, and at one time even with, the four port buttresses are three bilge boards (tablas de la canal), fashioned so that they could easily be removed to inspect the lower bilge area. Although still in place, the boards have been mashed down and broken by a ballast stone spill that apparently occurred at the time of the ship’s wrecking. In addition to the buttress rabbets, the port side of the mast step’s upper edge is slightly notched out to accept the inboard edges of the first and second bilge boards. This allowed for a tighter seam between the boards and the mast step. The two forward bilge boards are 70 cm in length and 21 cm in width. The third is broken, with its upper half missing, and is 17 cm in width. Each board is 2.5 cm in thickness.