Was thinking about this thread and wanted to add some related information links.
Basically to reinforce a few things…
1) The need to keep the cockpit lockers ALWAYS secured when sailing. Some people use carabiners.
2) The need to keep the hatch closed when the wind pipes up. (The hatch evidently stays above the water on a normal knockdown, butI wouldn't want to count on it)
3) Making sure you can quickly release the mainsheet and jib sheet, if the boat is going to be knocked down.
While the C22 is a keelboat, I often sail it like a small dinghy, ready to spill wind/let the mainsheet out as needed, not just in a knockdown situation
Making sure the sheets can run free without jamming, is very important.
From time to time people ask on these forums how far a Catalina can heal, will it tip, sink, etc. The answer to all of this is yes it can sink (it’s a boat) and yes it can be knocked down but I can now speak from experience that it is very gentle. I was racing my wing keel this year at the...
forums.sailboatowners.com
Saturday afternoon a sailboat sank off Oriental. It was not part of the racing taking place on the Neuse River. Catalina 22 sailboat “This Old Boat” had owner...
towndock.net
Click for a larger image
Of course this stuff also applies to bigger sailboats. Don't think for a second that a big sailboat can't be knocked down and sunk with water into ports and hatches.
I know of a 40ft+ monohull that did so, on the last day of a bareboat charter in the BVIs.
And there is Albatross, Pride of Baltimore etc.
en.wikipedia.org