The first six vessels of the class were fitted for anti-submarine warfare, and are additionally armed with triple tube 324 millimetres (13 in) B515 torpedo launchers from Whitehead Alenia Sistemi Subacquei S.p.A. (WASS).

The refurbishment plan was announced in March 2020 in response to the increase of sea robberies within the region, and foreign intrusions of Singapore territorial waters.

[3] In addition to refitting the vessels to extend their operational lifespan, the Sentinel-class MSRVs were fitted with a range of calibrated capabilities, including enhanced communications equipment, improved visual and audio warning systems, and modular ballistics protection on their superstructures.

As part of the refit, non-lethal LRAD and laser dazzling systems were added to increase operational flexibility, while fenders were incorporated into the hull to come alongside vessels of interest.

[5] Over the years, the patrol vessel fleet has participated in various maritime security missions, safeguarding Singapore's waters, and deterring piracy and sea robbery, as well as search-and-rescue efforts.

[11] In April 2012, ST Marine was awarded a contract by the Ministry of Defence of Oman to build four 75-metre (246 ft) patrol vessels based on the Fearless class.