Pre-Shrouded Vanes, DUCT. This device direct the flow of the water to the propeller for more effective flow so that the propeller will provide the best possible thrust with the least effort. This can give efficiency improvement between 3-7%.
Pre-Swirl Stator, FINS. This is similar to the above. We DO NOT have this on our vessels. This can give efficiency improvement between 3-8%.
Hub Vortex Absorb Fins, AVHF or PBCF. This is a small propeller type device which is fitted on the end of the propeller boss and it smoothens the vortex created by the propeller, thus reducing the drag. The efficiency improvement is between 2-5%.
We do have also high efficiency propellers fitted designed by MAN Kappel but obviously they cannot be considered as ESD. However, they do contribute to the efficiency of the vessel.