The Róisín-class large patrol vessel is a class of offshore patrol vessels (OPV) [2] ordered by the Irish Naval Service from December 1997.

[4] The class's primary mission is fisheries protection, search and rescue, and maritime protection operations, including vessel boardings.

The class was designed by Vard Marine (formerly STX Canada Marine) and has an all-steel hull based on the Mauritian patrol vessel Vigilant launched in 1995, but without the helicopter deck and hangar facilities.

The level of automation incorporated into the ships' systems allows the ships in the class to be operated with just 44 crew including 6 officers.

The class is designed for winter North Atlantic operations.