Del Pilar-class offshore patrol vessel

The Del Pilar class is a class of three offshore patrol vessels currently in service of the Philippine Navy, and are currently the foremost surface combatant of the fleet. These ships were formerly used by the US Coast Guard as Hamilton class high endurance cutters.

Originally designated as frigates, the class would be downgraded to patrol ships to better reflect their limited capabilities.

History
Early in 2011, the Philippine Navy announced the acquisition of an ex-US Coast Guard Hamilton-class high-endurance cutter under the "Ocean-going Escort Vessel" project through the US Excess Defense Article programme. The ship acquired was the former USCGC Hamilton (WHEC-715), renamed BRP Gregorio del Pilar (PF-15) which was officially turned over to the Philippine Navy on 13 May 2011 at Alameda Point in California. It was retrofitted and modified in the US, replacing systems removed by the USCG. The ship's arrival ceremonies were on 23 August 2011 in Manila, and it was commissioned on 14 December 2011.

A second Hamilton-class cutter, the USCGC Dallas (WHEC-716), was turned over to the Philippine Navy on 22 May 2012 with ceremonies held at the Federal Law Enforcement Training Center Pier Papa in North Charleston, South Carolina. The ship was named BRP Ramon Alcaraz (PF-16) in Philippine Navy service. Like its sister ship, it was retrofitted and modified in the US, replacing systems removed by the USCG. It was expected to arrive in the Philippines by February 2013. However, further training and unspecified upgrades on the ship pushed the arrival of the BRP Ramon Alcaraz to August 2013. The ship's arrival ceremony was held at Subic Harbor on August 6, 2013, led by President Aquino. It was commissioned on Nov. 22, 2013.

A third Hamilton-class cutter was turned over to the Philippine Navy after US President Barack Obama announced that another high endurance cutter will be transferred to the Philippines during his visit to the BRP Gregorio del Pilar on November 17, 2015. The White House subsequently confirmed that the USCGC Boutwell (WHEC-719) will be the ship that will be transferred to the Philippines.

Design
The ship was designed with a high level of habitability and provides fairly comfortable accommodations, including air conditioning.

Propulsion
The Del Pilar class are the first Philippine military vessels to employ the now common shipboard application of aircraft gas turbine jet engines with the use of controllable pitch propellers. The class are equipped with two 18000 hp Pratt & Whitney gas turbines and can propel the ship at speeds up to 28 kn. The class also has two 3500 hp Fairbanks-Morse diesel engines, capable of driving the ship economically at 17 kn for up to 14400 nmi without refueling. A retractable/rotatable bow propulsion unit provides manoeuvrability in tight situations.

Armaments
Prior to turn-over to the Philippine Navy, the Hamilton-class cutters were armed with a Mk.75 Oto Melara 76 mm Compact main gun, two Mk.38 M242 Bushmaster 25 mm chain gun at midships, and a Phalanx CIWS system aft. The CIWS and chain guns were removed by the United States Coast Guard prior to turn-over, with the Mk.75 gun remaining.

The Philippine Navy installed a Mk. 38 Mod. 1 25mm chain gun and two Mk. 16 20mm Oerlikon autocannons to the PS-15, and six 50-caliber machine guns on both the PS-15 and PS-16.

The Philippines ordered two new Mk. 38 Mod. 2 25mm naval gun systems in 2012, and these are expected to be installed to the ships of the class. On Feb. 17, 2014, it was reported that said chain guns were in the Philippines, waiting for the U.S. Coast Guard armament team for installation. As of January 25, 2015, 2 Mk. 38 Mod. 2 25mm guns had been installed on PF-16.

Another set of Mk. 38 naval guns, this time in Mod.3 variant were ordered in October 2015, and another contract for 2 units of Mk.38 Mod.3 25mm naval guns were ordered in September 2016. The first set of 2 units was installed on BRP Gregorio del Pilar (PS-15) on early June 2019.

Flight Support
The Del Pilar class has a flight deck and hangar capable of handling helicopters. A BO-105 light surveillance helicopter was initially assigned to BRP Gregorio del Pilar, and was replaced by the newer AgustaWestland AW109 Power helicopter. The helicopters first made their shipboard deployment on May 21, 2014.

Modernization
It was also reported that the Philippine Navy is planning further upgrades for the entire ship class. The upgrades will feature upgrades for navigation, propulsion, communication, surveillance, and weapons systems.

Several systems were acquired through US Foreign Military Sales (FMS) and Foreign Military Financing (FMF), which includes the BAE Systems Mk. 38 Mod. 2 machine gun system, the SAAB AN/SPS-77 Sea Giraffe AMB 3D air/surface search radar, and the FLIR Systems SeaFLIR 230 Electro-Optical/Infra-Red Camera.

Meanwhile, the Philippine Navy will launch a program to acquire, install and integrate several other sensors into the ship, as part of the Horizon 2 phase of the Revised AFP Modernization Program. Among those to be acquired are new Combat Management System (CMS), Hull Mounted Sonar (HMS), and a Radar Electronic Support Measures (R-ESM).