NRP Almirante Gago Coutinho

NRP Almirante Gago Coutinho (A523) is a ship of the Portuguese Navy' Dom Carlos I-class survey vessels (ex-US Stalwart-class ocean surveillance ship adapted in Portugal for the execution of hydrography and oceanography surveys). Before transfer to the Portuguese Navy, Almirante Gago Coutinho was formerly USNS Assurance (T-AGOS-5) of the United States Navy.

Design
The Stalwart-class ocean surveillance ships were succeeded by the longer Victorious-class ocean surveillance ship. Assurance had an overall length of 224 ft and a length of 203 ft at its waterline. It had a beam of 43 ft and a draft of 15 ft. The surveillance ship had a displacement of 1600 t at light load and 2301 t at full load. It was powered by a diesel-electric system of four Caterpillar D-398 diesel-powered generators and two General Electric 550 PS electric motors. This produced a total of 3200 PS that drove two shafts. It had a gross register tonnage of 1,584 tons and a deadweight tonnage of 786 tons.

The Stalwart-class ocean surveillance ships had maximum speeds of 11 kn. They were built to be fitted with the Surveillance Towed Array Sensor System (SURTASS) system. The ship had an endurance of thirty days. It had a range of 3000 mi and a speed of 11 kn. Its complement was between thirty-two and forty-seven. Its hull design was similar to that of the Powhatan-class tugboats.

History
USNS Assurance was a Stalwart-class modified tactical auxiliary general ocean surveillance ship of the United States Navy. Stalwart-class ships were originally designed to collect underwater acoustical data in support of Cold War anti-submarine warfare operations in the 1980s.

In 1999, ex-USNS Assurance was transferred to Portugal and is now NRP Almirante Gago Coutinho survey ship.