Years ago, I lived on my boat at Squalicum Harbor in Bellingham, WA. The boat was way, way out at the end of the dock – next to the breakwater on the end, in a physically huge basin. There were other boats around me, but I was the only one nuts enough to be living out there on the end, at the time. I was awakened one morning by the whack of something on the hull. Whack. Long pause. Whack whack (from different sides). I start to fall back asleep. WHACK!