カーフェリの輸送エネルギ効率について

Abstract

Recently, in Japan, the transportation by the car-ferry, especially by the long route car-ferry of which important cargos are trucks, is remarkably growing. This paper analyzes the characteristics and the present status of the car-ferry transport energy efficiency with regarding the role of the ferry as an alternative way of the land transportation by the truck. The hull resistance and propulsion efficiency of the ferry are better than the common cargo ship. This characteristic is due to the capability of differentiating the hull function into the buoyant support function and the shipment function. The payload-to-displacement ratio has a great influence on the transport energy efficiency of the ferry. This ratio is determined by the carriage deck area. Therefore the catamaran type hull is very favorable for the ferry.The estimation based on the actual transport energy efficiency reveals that the ferry transportation consumed about 1.4 million tons of oil fuels at 1975 in Japan. The ferry transport energy efficiency is estimated by the comparison with the land truck transportation. The result shows that, at the present, the small and medium sized ferry are worse than the truck, but the large sized, that is, long route ferry can compare favorably with the truck. The improvement of the payload-to-displacement ratio would extend the region where the ferry could be used as an alternative way of the land truck.