About 40 years ago, a Mariner got caught in a thunderstorm on Lake Charlevoix in Michigan. The boat ended up getting swamped (including the cabin). Fortunately, the boat didn't sink, and everyone survived ok. I don't know if it was the keel or the centerboard version.
I was out on my sunfish sailboat on the same lake but a few miles away, so I didn't see it first hand.