So when I teleport-turn the ship into the position below, the bow falls off the wind. I believe this is the scenario Lieste is describing as counterintuitive. However, if I repeat the experiment with all fore-and-after canvas doused, the ship turns bow to wind and even tacks itself. So the aerodynamic behavior of the square sails seems to be correct. This raises the interesting question of whether it is possible to tack the frigate while stationary...