Crosscut vs radial/tri-radial layouts all come down to the nature of Dacron. Dacron is a woven material, which has fibres running in two directions.
It's possible to distinguish the crosscut sails on their layout. When making a crosscut sail, you will have panels running horizontally and parallel to each other.
The material tends to be stronger in its so-called fill fibres, which are the ones that run perpendicular to the length of a roll of Dacron, and to make the most of this, the design of the crosscut panel was made.
An effective design
The idea of making sails from crosscut panels is also called a fill-oriented design. The layout is made to ensure that the strongest yarns are always running parallel to the leech, which is a very effective method as the strongest yarns run along the length of the narrow panels.
Working with a crosscut design has its benefits and drawbacks. The benefit is that the design allows a more effective and cheaper production, as less material is cut away in the production process - giving you a well performing set of sails at a good price.
The slight drawback to the crosscut design - in comparison to radial/triradial counterparts is that a crosscut sail tends to lose sail shape over time, where the competing radial layouts stay in shape better and for longer.
On the other hand, a radial/triradial design is also considerably more expensive to produce.