NRP Dom Carlos I (A522) is the lead ship of the Portuguese Navy's Dom Carlos I-class survey vessels (ex-US Stalwart-class ocean surveillance ships) adapted in Portugal for the execution of hydrography and oceanography surveys.

USNS Audacious 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 Portugal, Almirante Gago Coutinho underwent adaptation works towards its transformation into a hydro-oceanographic ship, in the Alfeite Naval Arsenal.

The Portuguese Navy has tried to fix it for almost a year but that work is very difficult because of lack of money and resources and tight budget.