Lofting is a drafting technique to generate curved lines. It is used in plans for streamlined objects such as aircraft and boats. The lines may be drawn on wood and the wood then cut for advanced

woodworking Woodworking is the skill of making items from wood, and includes cabinetry, furniture making, wood carving, joinery, carpentry, and woodturning. History Along with stone, clay and animal parts, wood was one of the first materials worked b ...

. The technique can be as simple as bending a flexible object, such as a long strip of thin wood or thin plastic, so that it passes over three non-linear points, and scribing the resultant curved line; or as elaborate as plotting the line using

computers A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ('' computation''). Modern digital electronic computers can perform generic sets of operations known as ''programs'', ...

mathematical tables Mathematical tables are lists of numbers showing the results of a calculation with varying arguments. Trigonometric tables were used in ancient Greece and India for applications to astronomy and celestial navigation, and continued to be widely us ...

. Lofting is particularly useful in

boat building Boat building is the design and construction of boats (instead of the larger ships) — and their on-board systems. This includes at minimum the construction of a hull, with any necessary propulsion, mechanical, navigation, safety and other ser ...

, when it is used to draw and cut pieces for hulls and

keel The keel is the bottom-most longitudinal structural element of a watercraft, important for stability. On some sailboats, it may have a fluid dynamics, hydrodynamic and counterbalancing purpose as well. The keel laying, laying of the keel is often ...

s. These are usually curved, often in three

dimension In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus, a line has a dimension of one (1D) because only one coo ...

s. Loftsmen at the mould lofts of

shipyard A shipyard, also called a dockyard or boatyard, is a place where ships are shipbuilding, built and repaired. These can be yachts, military vessels, cruise liners or other cargo or passenger ships. Compared to shipyards, which are sometimes m ...

s were responsible for taking the dimensions and details from drawings and plans, and translating this information into templates, battens, ordinates, cutting sketches, profiles, margins and other data. From the early 1970s onward

computer-aided design Computer-aided design (CAD) is the use of computers (or ) to aid in the creation, modification, analysis, or optimization of a design. This software is used to increase the productivity of the designer, improve the quality of design, improve c ...

(CAD) became normal for the shipbuilding design and lofting process. Lofting was also commonly used in aircraft design before the widespread adoption of computer-generated shaping programs.

Basic lofting

As ship design evolved from craft to science, designers learned various ways to produce long curves on a flat surface. Generating and drawing such curves became a part of ship lofting; "lofting" means drawing full-sized patterns, so-called because it was often done in large, lightly constructed mezzanines or lofts above the factory floor. When aircraft design progressed beyond the stick-and-fabric boxes of its first decade of existence, the practice of lofting moved naturally into the aeronautical realm. As the storm clouds of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

gathered in Europe, a US aircraft company,

North American Aviation North American Aviation (NAA) was a major American aerospace manufacturer that designed and built several notable aircraft and spacecraft. Its products included the T-6 Texan trainer, the P-51 Mustang fighter, the B-25 Mitchell bomber, the F- ...

, took the practice into the purely mathematical realm. One of that war's outstanding warplanes, the

North American P-51 Mustang The North American Aviation P-51 Mustang is an American long-range, single-seat fighter and fighter-bomber used during World War II and the Korean War, among other conflicts. The Mustang was designed in 1940 by a team headed by James H. Kin ...

, was designed using mathematical charts and tables rather than lofting tables.Lofting
melmoth2.com Lofting is the transfer of a ''Lines Plan'' to a ''Full-Sized Plan''. This helps to assure that the boat will be accurate in its layout and pleasing in appearance. There are many methods to loft a set of plans. Generally, boat building books have a detailed description of the lofting process, beyond the scope of this article. Plans can be lofted on a level wooden floor, marking heavy paper such as Red Rosin for the full-sized plans or directly on plywood sheets. The first step is to layout the grid, mark the Base Line along the length of the paper or plywood sheet. Then nail Battens every 12 inches (or more in some cases) where the station lines are to be set as a mark for the perpendicular line, which is marked with a T-square. The previous steps are followed in turn by marking the Top Line and the Water Line. Before continuing make sure to check the lines by using the

Pythagorean theorem In mathematics, the Pythagorean theorem or Pythagoras' theorem is a fundamental relation in Euclidean geometry between the three sides of a right triangle. It states that the area of the square whose side is the hypotenuse (the side opposite t ...

and make sure the grid is square. The second step is to mark the points from the table of offsets. All measurements off the table of offsets are listed in Millimeters or the Feet, Inches, and Eighths. The points are plotted at each station then use a small nail and a batten to Fair (draw with a fair curve) the boat's lines.

Definitions

;Full sized plan: A 1:1 scale construction drawing of a boat and its parts ;Lines plan: A scaled-down version of a full-sized drawing often including the body, plan, profile, and section views ;Body Plan: A view of the boat from both dead ahead and dead astern split in half ;Plan view: A view looking down on the boat from above ;Profile view: A view of the boat from the side ;Section view: Cross-section of the boat's width ;

Batten A batten is most commonly a strip of solid material, historically wood but can also be of plastic, metal, or fiberglass. Battens are variously used in construction, sailing, and other fields. In the lighting industry, battens refer to linea ...

: A long stick to help draw fair lines

References

Books

*"The Evolution of the Wooden Ship", Basil Greenhill, Sam Manning, 1988 *"The Boatbuilder's Apprentice", Greg Rossel, 2007 *"Lofting a Boat: A Step by Step Manual" Roger Kopanycia, Adlard Coles, 2011 {{Shipbuilding-Footer Woodworking Technical drawing Shipbuilding Aeronautics

Basic lofting

Definitions

See also

References

Books