3D vs. 2D... What's the Difference?

While the difference between the generic terms “3-dimensional” (length+width+depth) and “2-dimensional” (length+width) are relatively easy to grasp, understanding the difference between 3-dimensional and 2-dimensional sailmaking is a bit more involved.

While a sail itself has negligible “depth” (the thickness of the sailcloth or laminate from which it is made), when it is pressurized by wind it assumes a significant 3-dimensional shape... or, “flying shape.” Sail designers work hard to define the best shape for a specific sail, and the people who make the sail work VERY hard to achieve that shape on the water. It is in achieving the desired flying shape that the difference between 3D and 2D sailmaking comes into play.

2D sailmaking
The traditional method of sail construction is to stitch or glue together flat 2-dimensional segments (panels) of woven or laminated material to form the sail. Using a method called “broad seaming,” the edges of the panels are given curvature so that when the assembled sail is pressurized by wind, it will assume a specified flying shape. In essence, 2D segments have been assembled to emulate a 3D form. This is how sails have been made for hundreds of years and how all 2D sails are still made today.

3D sailmaking
A more modern method of shaping a sail is to laminate it on a full-sized 3-dimensional mold in the precise flying shape it will assume when sailing. The resulting sail will have smooth, compound curvature in all directions and sail loads will be distributed more efficiently. Only North 3D sails (3DL or 3Di) are manufactured on full-sized 3-dimensional molds using a patented process.

Following are several examples illustrating the essential difference between 3D and 2D construction...

North 3DL and 3Di sails are the only sails in the world that are manufactured 3-dimensionally (see below left). ALL other sails are manufactured 2-dimensionally (see below right). While 2D sails can be manufactured to look like a North 3D sail, only North 3D sails are molded 3-dimensionally with every structural element formed in the precise curved space it will occupy when sailing.
Another important difference between 3D and 2D sailmaking involves the unique thermo-forming process North uses in the manufacture of its 3D sails. After the lamination process is completed, vacuum pressure and heat are applied to the laminate while it is still on the mold (see below). The heat and pressure not only consolidate bonding within the laminate, they also cause the laminate to conform tightly to the mold in a manner similar to a shrink-wrapping process. This patented thermo-forming method means North 3D sail shapes are more accurate and more repeatable than shapes produced using any other sailmaking system.
© North Sails