Several years ago, two experienced fishermen were lost to Lake Michigan while trolling in calm water. Both of them were at the stern watching the fishing gear when the boat struck a floating timber, similar to a telephone pole. The contact angle caused the bow to climb the timber. The sudden change in angle pitched the two men over the side. The boat then settled out and continued to troll away from them. It was found beached on the shore, out of gas . . .
I can't imagine anyone going out to fish in a fair-sized power boat and not have an engine "kill" pin attached to them, for this very type situation.
In our area (KY) we have many bass fisherman who use high-speed boats in fishing tournaments. All use engine kill pins with a line attaqched to them, in case they do fall our of the boat. Should the boat be at a high throttle setting and the engine not shut down, the boat will react to thrust and torque, begin to circle. Fisherman have been run down and cut to death by their own boat, as it runs in circles.