The radial cut of the sail shades
All the fabrics commonly used for the production of indoor and outdoor furniture are produced in rolls, which can have different widths.
These rolls are then cut and sewn to package the finished product. However, there are two different ways to assemble the "panels" of fabric that make up a sail: "straight" cut also called cross-cut or radial cut.
The "straight" cut is certainly the fastest and cheapest, it allows a quick assembly and reduces any waste of fabric. Until 1983 all sails were produced with this system which ensures economy and good performance.
It should certainly be emphasized, however, that due to the low stiffness developed by this cut, the sail loses its vigor from a performance point of view.
The radial cut
The revolution occurred in 1983 with Tom Schnackenberg "sails-designer" of the consortium of "Australia II"; Tom takes advantage of the advent of modern cutting plotters and design software.
The sails with radial cut are produced with many more cuts and therefore require a greater number of cuts and seams, also increasing the waste of the fabric.
However, they guarantee better tensioning as each small bar is able to "transport" the force applied to the ends. It is as if each small triangle became the bearer of a force vector, which from the top of the sail points to the center.
This vector is accompanied by the strength of 4-5 other small vectors. All these vectors do not find "barriers" and point straight to the point where the force struggles to reach, ie the center of the sail. Compared to the "cross-cut" cuts that "block" the propagation of the force, the diagonal joining instead allows it to reach exactly the most delicate point.
By managing to "distribute" the force, we will be able to ensure that every piece is subjected to the tension it needs to remain in tension.
It should therefore be emphasized that the radial cut allows for a stiffer sail, less yielding under load and with a higher performance duration: it naturally works more homogeneously.
The nautical sails
If you look at the nautical sails of racing boats, you will notice that they are radial, or rather, tri-radial since they have to cover huge surfaces.
From these photos you will notice how modern racing boats use even more complex cuts and constructions, given that the software is always pushing forward and able to mix fibers and production methods, but the base is always a radial cut as you can see!