These vessels are equipped with a system to lubricate their progress through the ice, by bubbling air through the hull.

A SLEP is a major overhaul intended to extend a vessel's service life; it is typically scheduled as the vessel approaches the end of its originally planned service life.

The Bay-class tugboat SLEP project includes significant system upgrades and improvements to the propulsion plant; to the heating, ventilation, and air conditioning systems; installation of an engine-room fire-suppression system; boat launching davit replacement; Oily Water Separator replacement; stack exhaust configuration modifications; hull air-ice lubrication system; and crew habitability improvements to meet current standards (including removal of lead paint).

The first of nine cutters (Morro Bay) entered SLEP at the Coast Guard Yard on July 1, 2014.

[1] Morro Bay returned to her homeport of Cleveland in September 2015 [2]