This is my sailing experience every time I play Valheim. I'm starting to believe the devs put in an RNG variable that makes the wind constantly fight you for certain steam IDs or something.
Good explanation. Another way to think about it is with modern sails and hull design it's more like a wing. The sail above the water is the more obvious wing shape, and with some designs that use a centerboard or daggerboard that is like the other half of a wing turned on its side. With water having more drag than air, the centerboard is the continued wing shape under the water only shorter.