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lofting

lofting the shear

After the shop was prepared and the leaking roof dealt with, we were ready to loft. The lofting process takes its name from the location it would have traditionally occurred in: a sail loft. As boats, and the Malabar is a particularly extreme example of this, don’t have a single right angle to them, a full scale set of plans need to be drawn up to use as patterns for making various structural components. Thus boat plans come with a table of offsets giving x and y coordinates along the various curves of the hull. During the lofting process you mark all of these points by driving nails or ice picks into the lofting floor and spring flexible wood battens along them. I used 8 penny finish nails and hand spring clamps to hold the batten in place. You mark the line along the batten to get a fair curve and in this manner reconstruct a full size drawing of your boat.

As the floor of our shop is rough concrete (that slopes to the east) it was unsuitable for lofting on. Thus I had to build a low wood platform consisting of 3/8” plywood on 2×4 joists. The floor measures 16’ by 48’; ample room to lay out a profile, body plan and waterlines. I painted the floor flat white and made a series of battens ranging from 8’ to 46’ in various dimensions (the longer battens were 16’ lengths of pine scarffed together with a 1:20 joints).

The floor construction took allot of time, given that I was working alone, but the actual lofting went quickly. I laid out the grid in black pencil. I found I preferred using your standard No. 2 pencil along with a couple of mechanical pencils, which produce a more uniform width line. To make the final drawings more clear, I lofted the body plan in red colored pencil and the profile in blue. As the shear and waterlines of the plan view were offset from the profile by several feet (a luxury afforded by that 16’ platform width) I used red for it as well.

I will use the lofting to make the molds and backbone of the boat, after which I will demolish it to make room for the actual hull assembly.

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