Like a visit to The Land of Counterpane, the stately River Thames meanders for nearly 100-miles through the Oxfordshire countryside, its banks lined with forests, secluded meadows, castles, and opulent estates. Still, Winslow had a few facts to face while his wife and kids piled aboard the 50-foot narrow boat they rented: He had only ever piloted a little-lake outboard, knew nothing about river currents or navigation locks, and had better figure out who has the right of way in the face of oncoming commercial traffic….