It is important to reemphasize that the Mediterranean moulding design method does not rely on two-dimensional versions of the conceptual drawings in Figure 49a–f, g–l, m–r. Mediterranean moulding is a non-graphic system of design, and the actual definition of the frame shapes begins when the shipwright lays the template on a piece of framing timber (Figure 49r). What I hope these isometric drawings convey is that the quantification of "key" runs on a hull is the fundamental concept behind the increments of offsets marked on the templates used in Mediterranean moulding.
In fact, in Mediterranean moulding the shape of the hull beyond the tail frames was defined during construction using actual ribbands that were extended from the design frames to the ends of the vessel. The frames at the ends of the hull would be cut to match the hull shape defined by these ribbands. This process simply represents a physical extension of the same concept that was used for the design frames. In a Portuguese treatise by João Baptista Lavanha (ca.1608–1616) and an anonymous French treatise on galleys from 1691, supplementary methods are presented for predetermining the shapes of the frames beyond the tail frames (Lavanha ca.1608–1616:163–167; Traitté…galères ca.1691:19–32). Both these treatises describe methods of defining the shapes of the ends of the hull with graphic versions of ribbands depicted as narrowing and/or rising curves in the breadth and sheer plans of a drawing. These treatises do not contain a transverse view of the ribbands as do the French drafts discussed in this essay; however, these ribbands are conceptually presented as graphic extensions of the design between the tail frames.
Even in the most elaborate versions of Mediterranean moulding the change in hull curvature is only defined along two longitudinal curves on each side of the vessel. The lower narrowing and rising offsets quantify change along the bilge curves, and the upper narrowing and rising offsets adjust the change along the breadth curves. The standardization of transverse shapes above, below, and in between these controlling curves allow for the complete hull shape to be defined between the tail frames. This concept of using mathematically defined longitudinal curves to provide guide points for drawing or positioning transverse shapes with restricted geometry is the essence of the geometric fairing method (Rabl 1941:28, 38). Using this approach, shipwrights for centuries were able to successfully duplicate the basic hull shapes of vessels they deemed successful and make quantifiable changes to generate new hull designs. Indeed, Mediterranean moulding was probably the dominant method used in French naval shipyards through the end of the seventeenth century (Rieth 2001).
Although it is possible to develop quite complex curvature using Mediterranean moulding design, this method has an inherent limitation. NEXT
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