Have a look at these [1] polar diagrams for tall sailing ships. The radial distance from the center is the theoretical boat speed and the angle is the direction that the wind is hitting the boat, with zero on the nose and 180 from the stern. Each plotted line is the boat speed for a given wind speed. They show how the square-rigged ships can't sail upwind any closer than 55 degrees or so and are fastest on a broad reach (wind from just back of the side). You can also see how longer boats are generally faster, but a smaller boat with triangle sails ("Bermuda rigged") could easily get away from a big square-rigged ship by heading more upwind.

[1] https://forum.zegluj.net/download/file.php?id=23628&mode=vie...

Interesting for reasons unrelated to TinyWind: What are the numbers on the left edge, boat speed in knots? Also, from what place and time is the technology on which these diagrams are based?

And what is this forum that unfortunately I can't read? Who made these diagrams?