OK, here is a better benchmark. By decreasing the Wind Lift Coeff and Water Lift Coeff, the ship can no longer sail too close to the wind with all canvas set. The screenshot shows how leeway will punish you if you try.
However, tacking is still a bit too torturous, at over 4 minutes. This time isn't necessarily excessive, but you barely have enough inertia to get head to wind, and would probably fail in light airs. What settings should I adjust to make the ship keep forward momentum for longer?
I will try the new test build later.