Energy Saving Device

An energy-saving device is a hydrodynamic appendage fitted around the propeller or stern to recover rotational energy or improve inflow, cutting the power needed for a given speed. Common types are pre-swirl stators, wake-equalizing ducts such as the Mewis Duct, propeller boss cap fins, and rudder bulbs, typically delivering 3 to 8 percent savings depending on hull and loading. They improve attained EEDI and EEXI and help the CII rating, and many are retrofittable at a dry-docking, making them a low-risk first step in a decarbonization plan.