I was sailing in a Cal 20 with to much sail up for the conditions 25 knot winds, when a 40 -50 knt gust knocked the boat flat, with mast hitting water etc... I was on the leeward side and got swept out of the boat due to fast water coming over the side. Fortunately I grabbed the ladder and my sailing partner knew enough to release the sails. The boat quicky popped back up (thank god for those Cals). But being keel-hauled behind a fast moving boat was quite the experience!
We were fine but I learned a valuable lesson the hard way. Nowdays I slow down, reef early, and use a lifeline.