As she lost speed, you had to turn the wheel or tiller even more to keep her head to windward, and the effect of applying hard rudder was like applying the brakes, slowing her even more.
Except the rudder was stuck nearly centered. I think it was a lobster pot stuck on the rudder, that along with excessive lee-way caused increasing heeling. Once heeled enough, the line slipped free...
Or, maybe Poseidon was just pissed that day.