The asymmetry of the first seven strakes on the port and starboard sides of this vessel is regularized with these eighth strakes. Patrice Pomey refers to these as the "adjustment strakes" (Pomey 2009:59). Pointing to the upper edges of these strakes are regularly spaced "arrow" marks corresponding to frame positions (Figure 53). In this vessel framing timbers were added only after parts of the hull shape were defined by the edge-joined shell of planks, thus the "arrow" marks on these longitudinal runs were made prior to the insertion of the framing. The next strakes above the "marked" adjustment strakes are thicker planks known as wales; these wales clearly define the lower "sectors" of planking on both sides of the vessel.

Such distinct "sectors" of planking are also evident in an end-on view of the planking of the second Nemi ship from the middle of the first century A.D. that was discovered in Lake Nemi, Italy (Figure 52). On this vessel the "sectors" of planking in the lower hull are also bounded by wales. Such an end-on view allows us to visualize these "sectors" from a modern perspective, but researcher Marco Bonino has proposed that the formal definition of the longitudinal geometry of some of these runs constituted part of the design of the hull (Bonino 1989; Pomey 2009:60).

Centuries separate these two examples, and many more intervene before the earliest evidence for the use of the Mediterranean moulding design method in conjunction with frame-first construction; this does not allow us to draw any direct "evolutionary" connections. However, these examples, together with the above presentation of Mediterranean moulding, underscore the existence of universal features in the geometry of planked hulls that would have been evident to shipwrights undertaking a transition from shell-first to frame-first construction—whenever and to whatever degree. I believe that ultimately the practice of regulating hull curvature along designated strake runs, whether normal runs or not, led to the quantification of idealized plank or ribband runs in geometric methods of hull design (for related views, see Barker 1988:544–547; Boudriot 1994:50–51; Sarsfield 1988:70–72; 1991:141–144). I propose that to be able to quantify such runs, they were broken up into their narrowing and rising components. This enabled offsets to be generated for practical use in ship construction, for example, in marking templates for frame-first construction.

Upper Narrowing and Rising

To gain independent control over the curvature higher up in the hull, in more advanced versions of Mediterranean moulding, additional offsets were introduced to allow the curves of the upper hull to narrow and rise differently than those in the lower hull.

In Figure 49o an additional set of offsets reduces the slope of the rising curve at the breadth surmark. Analyzed graphically, this upper rising adjustment reduces the slope of the diagonal in the body plan. NEXT