Air bubble lubrication (ABL)

Air bubble lubrication (ABL) is a drag-reduction technology that pumps compressed air under the flat bottom of a hull to form a carpet of bubbles or an air layer that lowers frictional resistance between the steel and the water. Mitsubishi’s MALS (Mitsubishi Air Lubrication System) is the named commercial version, retrofittable and applied to flat-bottomed ships such as module carriers, ferries, and some bulk carriers. Net fuel saving depends on the air-compressor power against the friction saved, so gains are reported in the low single-digit to high single-digit percent range and are larger on wide, shallow-draft hulls. It is one of the energy-efficiency measures counted toward EEXI and CII performance.