Accounting for ship manoeuvring motion during propeller selection to reduce CO2 emissions

Abstract

The aim of this research is to reduce Carbon Dioxide emission through enhanced propeller selection achieved by a more realistic identification of the true propeller operating point. By recognising that the ‘dead-ahead steady speed in flat calm water’ condition is not representative of the true operation of a ship in a seaway, a new paradigm is proposed. By taking into consideration the effects of wind and waves on the ship's true speed through the water and thus the probable load condition of the propeller, throughout the ship's mission, a probable propeller operating condition is identified. Propellers are then selected for both the original condition and the adapted condition, and their performance compared using time-domain mission simulations. The objective of the study is to demonstrate how the alternative propeller selection methodologies proposed, can on average provide greater overall efficiency.Results from the case studies are encouraging, with a gain of 2.34% in open water propeller efficiency for a 3600 Twenty foot Equivalent Unit container ship, equating to a saving of 3.22% in Carbon Dioxide emissions.