Several years ago, while working as a mechanic at a marina, I watched a boat owner land his 40-foot sloop on a dock in textbook fashion, coming alongside, shifting into reverse smartly and bringing the vessel to a halt. The owner then jumped onto the dock with spring line in hand, but as he prepared to make it fast to a cleat, it was pulled from his hand. The vessel, it turned out, was still in reverse, and because the rudder was still slightly over, it described a large circular path, whereupon it made contact with the dock once again and was brought under control. A similar event occurred in 2005, with far greater consequences, when a ferry in British Columbia crushed 22 boats berthed in a marina adjacent to the ferry slip as it lost control while landing. The culprit in both cases? A single failed cotter pin.