Maneuvering Method for Energy-Saving of Contra-Rotating Propeller System on Purse Seiner "Nippon Maru"

Abstract

A contra-rotating propeller (CRP) system was installed on the purse seiner Nippon Maru in 2006. This system utilizes two propellers that operate in tandem while rotating in opposite directions from each other. The front propeller is driven by the main diesel engine while the rear propeller, which is installed on the rudder, is driven by an electric motor. This system is expected to produce improvements in propulsion efficiency over conventional propulsion systems consisting of one main engine and a single propeller. In this study, experiments aimed at measuring fuel consumption of the Nippon Maru were conducted to evaluate the fuel-conservation effects resulting from variations in front and rear propeller speeds. The results showed that the fuel consumption under CRP operation was 15% less than that experienced during same speed operation of the vessel using the front propeller alone. Furthermore, it was found that the fuel consumption of Nippon Maru using the CRP system was lower than that of a similar conventional purse seiner with a single engine/propeller system at medium speeds of between 11 and 15 knots, although no such decrease was seen at high speeds. In the future, an integrated control system for controlling both propellers using a single throttle control lever should be developed.