What happens if...

[Barquito]

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.

[smurphny]

I have had an apparent loss of steering a couple of times when hitting a current that matches boat speed hence, no rudder effect. Maybe you lost enough speed to have this happen??? Actually had this happen once right in The Race with the current ripping and thought for sure I had lost the rudder or something.