Okay hear me out and this may sound like the ramblings of a lune but i just thought the following.
Surely a perfectly flat tight sail would more effectively convert wind energy into forward momentum rather than a full sail which would first have the wind hit it at a slight angle pushing the sail in that direction rather than perfectly straight forward.
I realise there are practicalities in operating a very high tension sheet but this lives purely in the hypothetical realm.
Does this make sense or have i been drinking drain cleaner again.
Ta Lemmers…
Sails don’t really work like that. Sails are actually more like a wing. They create lift but pull sideways instead of lifting like airplane wings.
There are also crazy racing sailboats that use a ridged wing.
https://en.m.wikipedia.org/wiki/Wingsail