Swingers
There was a story a few years ago about a Fast 40 sailing to Bermuda that lost its drop keel along the way. The bolt(s)? holding the daggerboard-like design with a weighted bulb sheared off about three days out from the U.S. coast. They capsized and the boat sank. Luckily, the two people aboard were picked up by a cruiseship shortly afterwards. It probably didn't seem like such a short time to them. More recently is the story of the canting-keel on Skandia, I believe, in the 2004 Sydney-Hobart race. Her canting mechanism broke in the race last month, they withdrew from the race, and the keel subsequently fell off. I'm not sure if they were towed in right side up or upside down. Centerboard boats have made lots of long voyages even after damaging or losing their boards, but they don't depend upon the board's weight to stabilize the boat the way moveable keels do. If you're planning to head out of sight of land, it would be well to REALLY check thoroughly everything heavy that might move on your boat, and make sure it doesn't. The best way to do this might be to find a boat with a fixed keel.