On Lofting Maryland Dove
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Lofting is a process of drawing a complex vessel to scale typically from a set of plans in order to fair curved shapes, record bevels and rabbet lines, and conveniently build patterns or templates for construction. Fairing is the process of ensuring that all lines drawn and thus built are free of bumps, awkward flat spots, and hard to build curves. Fairing is accomplished by bending long wooden, plastic , or fiber glass “battens” around points relative to known grid lines and then comparing those bent lines to their corresponding lines drawn in two separate views.
There are many techniques and methods in recording information from a lofting and in drawing specific lines, however the foundational concepts as far as drawn views are concerned are more or less universal. There are three views often drawn overlapping one another and a fourth sub-view. The first is the “body plan”- a view of the vessel looking dead ahead or dead astern through the vessel. The second, the “profile”, is a view broadside, that is, viewing the vessel directly from the side. The third view is the “half-breadth”, or a birds-eye view of the vessel where the vessel is bisected directly down the middle through the fore and aft line. A last partial view is occasionally added somewhere above the lofting, which shows projected “diagonals”, more on that later.
Each view includes three types of drawn lines (and sometimes a fourth) which will come to represent the shape of the vessel. In each view two of the lines are straight and often double as grid lines, and one of the three types of lines are curved. The first type are called “station lines”, in the half breadth and profile view they are straight slices- like a bread loaf, and in the body plan they are curved lines which may approximate or directly represent the vessel’s framing. The second, the “waterlines”, are straight lines in the profile and body plan and are slices through the vessel like you would fillet a fish or cut a bagel. They follow theoretical waterlines as the vessel sits higher or lower in the water and are curved in the half-breadth view. The third are called “buttuck lines” and are typically the most difficult for a newby to conceptualize, they are slices through the vessel like you would cut focaccia- they are straight lines in the body plan and half-breadth and curved in the profile. Lastly, we draw diagonals through the body plan, which most closely follow the planking schedule and help us determine how difficult our vessel may be to build. When projected they might look similar to the water lines in the half breadth view, but are actually much more helpful in fairing the shape of the vessel as they more closely approximate what will actually be built.
Lofting begins with a smooth flat surface and carefully drawn grid lines to a convenient spacing. Points are traditionally drawn from a “table of offsets” provided by an architect which are relative measurements of points to loft given in feet, inches, and eighths. A baseline is selected to draw the half-breadth from and it is decided if you would like to loft to the inside of the planking (outside of the framing), or to the outside of the planking which will allow you to draw a vessel more accurate to what the finished vessel will look like. The first is more convenient and useful for building, the latter for designing.
Typically the profile perimeter, half breadth perimeter, and a midship station in the body plan are drawn. Afterwards, a few more bodyplan stations, a load water line in the half breadth, and a quarter-beam buttuck in the profile. As more waterlines, stations, and buttucks are drawn, intersecting points are compared against one another in the corresponding views and small errors down to a sixteenth of an inch are corrected. You begin with a lot of freedom and slowly lock yourself into your lofting. Mistakes and errors are easy to fix early on and can take a lot of time to work out further down the line.
Joinery details in the backbone build, rabbet lines, and frame bevels can then be recorded and used for the build. Shipwright, Spencer Sherwood worked on the lofting nearly single handedly for a month and a half. Master shipwrights Ed Farley and Frank Townsend helped with corrections for the last month, with the supervision of lead shipwright Joe Connor.
A brief history: Lofting was developed naturally during the 19th century as shipbuilding was industrialized and there was interest and economic demand to build vessels with a high level of precision in a production line fashion. Instead of vessels being built “by rack of eye”, using tacit knowledge and understanding perhaps aided by geometric or proportional rule- vessels were now being built piece by piece with the exact dimension of pieces known, you could theoretically cut to the line and install. Before lofting and still to this day in many boat building traditions, pieces were built to approximation and material was deducted by dubbing as further information was gained during the course of the build. It should be noted that the historic Dove, and all 17th century vessels for that matter, were not built using lofting; the methods of building were based in geometric rule, proportion, and passed on inherited and tacit knowledge. Certain aspects of the build were determined by general desired type to be built as well as tonnage. Simple drawings were often made showing backbone details and frame spacing. These methods of building are now far from our practical knowledge. They may have been implemented in an experimental manner, but with a much slower time line in the construction. Today, most traditional boat builders build by analog lofting, computer aided drafting, or a combination of the two- as we are for the Maryland Dove.
STH
