Eventually it made sense that boat-speed only changes the "apparent wind", as it's only simulating wind-boat interactions, not water-boat interactions.
But to get the sail-wind interaction you need the movement of the boat. To get the movement you then need the hull-water interaction. Modeling just a static, vertical, sail doesnt really demonstrate anything practical. It is more akin to similating a captive foil in a wind tunnel.
The obvious next step would be to calculate the cog and tilt the entire rig in response to sail forces, which sheds wind until a balance point is reached, or the boat flips.
The obvious next step would be to calculate the cog and tilt the entire rig in response to sail forces, which sheds wind until a balance point is reached, or the boat flips.