Improving the Performance of Three Classes of Double Ended Ferries

Washington State Ferries has updated the propeller design on three classes of double ended ferries. The goal of the upgrade was to improve fuel economy, reduce vibration and improve the comfort and reliability of the vessels. The vessels are run on various routes throughout the system at various service speeds and durations. The propeller designs were evaluated against the original designs using CFD and full scale measurements on the vessels. A comparison will be shown for each class including the improvements in fuel economy, vibration levels and vessel reliability looking at both the pushing propeller as well as the pulling propeller. A discussion will be provided in regard to loading and optimization of the split between the bow and stern propellers with respect to fuel economy and vibration. The discussion will conclude with the range of initiatives WSF is undertaking to reduce fuel consumption, reduce greenhouse gas emissions and maintain on time performance.