I cruised as a liveaboard for 7 years in the 90s doing most of the Atlantic circuit from Wales in a well sorted 38 foot steel ketch.
Getting caught out in the gulfstream when a mini low formed and it went to the north and blew 20 knots off south Carolina was by far the most unpleasant experience I had. I was more or less centered in the stream and intending to go around Cape Hateras as I had a clear forecast for 10 to 15 knot SE winds and no sytems of note. It was the only time I had green water on the foredeck on a consistant basis. The only time I felt that it might be dangerous to turn the boat beam on to the seas.
The sea state changed in less than an hour from a comfortable 6 to 8 foot swell to 8 to 10 feet steep sided breaking waves with frequent changes in direction. Every so often several seas seemed to get together and form a much larger breaking wave. Fortunately I was able to run for Murrels Inlet with a quartering sea but it was difficult to steer and several times I punched the bow deep into a wave and had to worry about the integrity of the windows in the hard dodger. I had a powerful autopilot which was totally unable to cope.
I was really grateful to be able to follow a shrimper into the inlet. Several items which were well lashed down on deck were lost. Had I had the typical cruisers board with jerry cans lashed to it they would have gone too.
That was not fun at all.