Cú Feasa was taken out of service in 1976 due to poor condition, leaving Lough Beltra as the only remaining Irish research vessel.

Its roles included fisheries, oceanographic, coastal, geographic, and environmental research, and acting as a training vessel for marine scientists.

It was fully controlled from the bridge and fitted with modern equipment including a Decca auto pilot, track plotter, navigator and radar.

[7] Between 1992 and 1994, the Lough Beltra received a £0.7 million upgrade, with 75% of the cost being funded by via the EU's STRIDE investment in regional research, technology and innovation, and the rest by the Irish government.

[8][9][10] This upgrade included structural alterations, the purchase of state-of-the-art sampling and monitoring equipment and a computerised data acquisition system.