Despite its importance, the midship frame provides only one cross-sectional shape along the whole length of the vessel. To appreciate the challenge of defining the rest of the hull's shape, it is helpful to remember that, at this point in the design, there is only empty space between the midship frame and the ends of the hull.
The Floor Diagonal
La Belle's archaeologically documented surmarks are located on frames at evenly spaced intervals, and they delineate smooth longitudinal curves. However, at this point in the design, neither these frame locations nor any longitudinal curves have been defined. This all begins to change by the creation of the floor diagonal.
In other drafts, like that of the Profond and the Cochois frigate, the floor diagonals at amidships begin at the ends of the floor width (Figure 6, 18). On La Belle the distance between the documented locations of the lower surmarks, ff', for the floor diagonal is 8 ft 2 inches, which is 8 inches greater than the 7½ ft between point J and J' in the midship frame reconstruction (Figure 27f). The clue to arriving at an explanation for this eight-inch discrepancy came from reconstructing the complete length of the lower diagonal both forward and aft. The surviving surmarks define oblique straight lines, and these lines can easily be extended to the centerline of the vessel. The devis states the height of the floor diagonal in the bow should be 3 ft 6 inches and its height in the stern 5 ft 6 inches. At the centerline of the vessel, the extended floor diagonal both forward and aft is just a few inches higher than these devis measurements. However, 4 inches to either side of the centerline, the heights correspond with those in the devis (Figures 27f, 28b). The interpretation that these 4 inch offsets added together represent the 8-inch theoretical sided dimension of the centerline timbers overcomes many of the difficulties in deciphering La Belle's design.
The sides of the centerline timbers are represented in the midship frame reconstruction as lines LM and L'M'. In the reconstruction of the midship frame, 1/4 of the beam, 3 ft 9 inches, was measured to either side of the centerline, AD, to establish the lines IH and I'H' and the endpoints of the floor width, J and J', on these lines (Figure 27c). However, when positioning the floor diagonals, I propose that the same distance was laid off from the lines LM and L'M' and not the centerline (Figure 27f). This same 4-inch offset seems to have affected the positioning of La Belle's upper bilge surmarks (Figure 28b) at points g and g' as well (Figure 27f).
There is one problem with this explanation: The actual timber dimensions of the preserved keel are 6 inches sided and 8 inches moulded. However, there is comparative documentary evidence to support the proposed larger square-sectioned design keel, and the disparity in scantlings can be attributed to timber availability or selection during construction (AN 1679b:Marine D1–15; MnM 1684a:PH 179610–179613). NEXT
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