The failure at sea of a number of merchantship propeller blodes initiated a research program supported by the Maritime Administration, the American Bureau of Shipping, the American President Lines and the States Steamship Company. Although extensive theoretical work has been carried out in the past (predicting propeller operating stresses), very little full-scale experimental stress measurements have been obtained. Brewer Engineering Laboratories, Inc. was retained by the sponsors to attach and protect fifty strain gages on the test propeller at the locations chosen by Littleton Research and Engineering Corporation. The propeller strain gages were protected from the severe environment by means of synthetic rubber and metallic overlays. The gage wiring was led down each blade and into a specially machined, hollow tailshaft through a waterproof bulkhead. The S.S. “Michigan”, with the test group aboard, sailed from Long Beach, Calif., in April 1970. The ship called at the ports of San Francisco, Yokohama, Naha, Manila, Bogo and Hong Kong during the test period. Throughout the trip across the Pacific, the gaging and instrumentation functioned without degradation or evidence of distress after onemillion propeller shaft turns. At the end of five weeks at sea and two-million turns, all but eight gages exhibited low ground resistance. The S.S. “Michigan” went into dry dock at the Bethlehem Steel Shipyard at Terminal Island, Calif., on June 15, 1970. The propeller was removed and all strain gages checked for continuity and ground resistance. Forty-two of the original 50 strain gages were found to be intact. No sign of deterioration due to cavitation or electrolysis attack existed on the metallic overlays or spot welding. Wire chafing within the fairwater adapter cap accounted for the low ground resistance values observed at the end of the voyage to Hong Kong.