There are those who do. https://en.wikipedia.org/wiki/Wingsail https://en.wikipedia.org/wiki/Wingsail Apart from being complex and expensive, you can't reduce

There are those who do. https://en.wikipedia.org/wiki/Wingsail https://en.wikipedia.org/wiki/Wingsail Apart from being complex and expensive, you can't reduce their size for hard winds. Rigid sails seems very inconvenient to fold too.