the first thing we did when we set up the bulkheads, was to locate their exact position fore and aft and mark it on the longitudinal members of the strongback perpendicular to the centreline. using a long tape measure prevented accumulative errors. with a little arrow and a second line we marked if the bulkhead was to be set forward or aft of the stationline.
we build the catamaran upside down and to keep everything level we had to rise most of the bulkheads as can be seen in the picture above. the two floats have a negative sheer so the highest point of the sheer is located somewhere amidships and not like in traditional hulls at the stem or transom. the station/bulkhead closest to this highest point we sat on the strongback which we assume the baseline. from the drawings we could then establish the height of the support risers for the remaining bulkheads.
a quick and easy way to do this was to create slots from three strips of ply. the “sandwiched” layer of ply is cut to the required height and the two face layers a bit oversized. so the bulkhead can slide in this created slot and can be clamped or screwed in position.
all bulkheads had waterlines and centrelines cut by the cnc router at swallow boats so with the help of a laser it was easy to align them. at this stage we weren’t to worried about having the bulkheads fixed plum as we were using the stringers at a later stage to locate them in their correct position.
