English: LÉ Eithne (P31) is an Eithne class ship in the Irish Naval Service. The ship is named after Eithne, a tragic heroine and the daughter of the one-eyed Fomorian King, Balor in an early Irish romantic tale.

Eithne was originally built as a long range fisheries patrol vessel, intended to be at sea for up to 19 days. It was originally planned to order four vessels of this class, but budget restrictions prevented this.
Eithne can also carry a SA365f Dauphin helicopter, and is the only ship in the Irish Naval Service fleet to have a flight deck. Helicopter operations have stopped in recent years, due in part to the purchase of CASA CN235-100MP Persuader Maritime Patrol Aircraft and decommissioning of the Dauphin helicopters. The vessel was fitted with retractable fin stabilisers to reduce rolling during helicopter operations at sea.
Eithne is currently the flagship of the Irish Naval Service.
Eithne was the last ship to have been built in the Republic of Ireland, constructed at Verlome Dockyard at Rushbrook, Cork and completed in 1984. Shipbuilding operations ceased at the yard in 1984, and the yard went into receivership.
In April-June 2006 the LÉ Eithne travelled to Buenos Aires in the first-ever deployment of an Irish warship in the southern hemisphere, in order to participate in commemorations of the impending sesquicentenary of Brown's death, and to bring back a statue of William Brown (admiral) to be displayed in Dublin.

http://en.wikipedia.org/wiki/LÉ_Eithne_(P31)