How does curvature affect the sail?
The fabric needs curvature to maintain stability and it will be pulled taut and slightly twisted to achieve this. This curvature plus the sail not being on one level plane – will make the sail more stable in winds. A flat sail will not perform properly and can hold water. The most common method is to have each pair of diagonally opposite corners at sgnificantly different heights. Shapes that have little curvature and tension will deform under load and become unstable and move about.
