by how quickly my red 11' dinghy became hard to spot in fairly good sized seas (7-9' perhaps). Also by how much ground we covered running downwind at 6.5-7kts before getting turned around. I was in the middle of rolling up some jib when it swamped and snapped the painter. When I got turned around, my wife had lost sight of it although I could see it. If it had been a person it may well have ended in tragedy. We had just installed a new chartplotter in the cockpit but not one of us thought to hit the MOB button in the confusion. We have considered the implications of this and will be practicing the drill a LOT more in the future and instituting some PFD and harness protocols for future trips.