Andres Bonifacio - class frigate The " Andres Bonifacio " class is a ship class of four frigate s that served with the Philippine Navy from 1976 to the mid - 1990s . These ships were formerly used by the US Navy as " Barnegat " - class small seaplane tender s and by the US Coast Guard as " Casco " class weather heavy endurance cutters . Under the Philippine Navy , the four vessels have undergone upgrades and modification , and were categorized as frigates . During their time , they were considered as the largest Philippine Navy combat ships of her time . History . The " Barnegat " class small seaplane tenders also served in the US Coast Guard as the " Casco " class cutters . These were actually quite interesting little ships , but they get overlooked . The only class of purpose - built small seaplane tenders in the US Navy , they were designed to operate out of small harbors and atolls and had a shallow draft . The fact that the class was very seaworthy , had good habitability , and long range made them well suited to ocean - station duty . Fast , heavily armed and exceptionally versatile , they served in a wide variety of roles during and after WWII . Seven units were provided by the US Government to the South Vietnamese Navy between 1970 and 1972 . On 29 April 1975 , with the South Vietnamese government collapsing and North Vietnamese troops entering Saigon ; six of the seven ships set sail and later made a rendezvous at Son Island , the last remaining morsel of free South Vietnam . They remained at anchor until 2 May , when they set sail for Subic Bay , still flying the South Vietnamese flag . Once they arrived in the Philippines , they presented a slight legal dilemma to the USN as in theory they should have reverted to the new “ provisional government ” in the former South Vietnam . Eventually it was decided that since the United States did not recognize that government , they were nobody ’ s property , and were sold to the Philippine navy in 1976 to spare the US government from the expense of having to move them out of Subic Bay for disposal . All were in poor condition , the last pair so much that they were beyond economic restoration . In 1979 , the entire aft deck on the remaining four was replaced by a helipad for one Bo - 105 helicopter , and a 3 ’ 3 ” tub for a displaced aft 40mm mount was added . Final radar fit was AN / SPS - 53 , AN / SPS - 29 , and Mk26 . Technical Details . There were changes made to the " Andres Bonifacio " class as compared to their original design during its service with the US Navy , US Coast Guard and the Republic of Vietnam Navy . The ships were passed to the Philippine Navy with fewer weapons on - board and old surface search radars , and these were addressed later on by the Philippine Navy through modernization programs , including the addition of a helicopter landing pad in 1979 . The single Mk . 12 5 - inch / 38 - caliber ( 127 mm ) gun was " Andres Bonifacio " s primary weapon . It was mounted in a Mark 30 Mod 0 enclosed base ring and had a range of up to yards . The gun was a dual - purpose type , capable of both antisurface and antiair warfare . She also carried a two twin Mk . 1 Bofors 40mm L / 60 anti - aircraft guns and two single Bofors 40mm L / 60 anti - aircraft guns , four twin 20mm Oerlikon cannons , four M2 Browning . 50 - caliber ( 12 . 7 - mm ) general - purpose machine gun s , and two 81mm mortars . Radar system installed include the Sperry AN / SPS - 53 Surface Search & Navigation Radar replacing the previously installed AN / SPS - 23 , while retaining both the AN / SPS - 29D Air Search Radar and Mk . 26 Mod . 1 Fire Control Radar System . Hatch and Kirk , Inc , added a helicopter deck aft in 1979 . Although the ship had no permanently assigned aircraft and could provide no servicing for visiting helicopters , the helicopter deck could accommodate a visiting MBB Bo 105 C helicopter , used by the Philippine Navy for utility , scout , and maritime patrol purposes . The ship was powered by two Fairbanks - Morse 38D diesel engines with a combined power of around 6 , 200 brake horsepower ( 4 . 63 megawatts ) driving two propellers . The main engines could propel the 1 , 766 - ton displacement ( standard load ) ship at a maximum speed of around . The ship had a maximum range of at an economical speed of . The Philippine Navy made plans were made to upgrade the entire ship class with new radar systems and the BGM - 84 Harpoon long - range anti - ship cruise missile , but this did not materialize due to the worsening political and economic crisis in the Republic of the Philippines in the mid - 1980s .