Dirk Nash raced the boat ahead as if he was a NASCAR driver. He knew one throttle position: wide open. The big johnboat blasted through the bottoms, then followed a submerged roadbed. It veered down a winding creek channel, then a flooded logging trail through a stand of tall timber that was ghostly in the dawn twilight. For the uninitiated, it was a white-knuckle ride. For Nash, a guide who had made the run countless times, it was just a way to get to his duck hole without wasting time.