The Bay class is a class of eight armed patrol boats, built by Austal and used by the Customs Marine Unit of the Australian Customs and Border Protection Service. They entered service during the late 1990s and early 2000s, and are primarily used on border protection duties.

A patrol boat is a relatively small naval vessel generally designed for coastal defence, border security, or law enforcement. There are many designs for patrol boats, and they generally range in size. They may be operated by a nation's navy, coast guard, police, or customs, and may be intended for marine, estuarine, or river environments.