for thrust and the diameter centrifugal fan for lift. The transmission served to link the engine and lift fan so that the fan could provide lift and thrust. Twin rudders and elevators sat behind the fans. As a hovercraft, the PACV could skim over water, including shallow and reed-choked waters, flat land, and ice. The PACV/ACV was very fast compared to contemporary watercraft, being capable of speeds up to . It had a range of and endurance of seven hours The Army hovercraft, called Air Cushion Vehicles, had more extensive modifications. They had heavier armor and reinforced, load-bearing decks. Army ACVs carried of armor—roughly equal to that of an M113 armored personnel carrier. The armor was thickest around the engine, transmission, and fuel tanks, providing protection from .50 caliber rounds fired at , while the armor around the crew compartment could only block .30 caliber rounds fired at . To save weight, many crews removed the armor around the crew compartment, and an Army evaluation recommended that it be removed altogether because of it "did not provide any protection to the crew," especially against heavier weapons such as recoilless rifles, artillery, and RPGs. The communications package consisted of a six-station intercom system, UHF radios, and a radio security set. The boats were shipped with AN/ARC-54 FM radios. However, these proved unreliable, with an operational ready rate of only 35 percent. Army units sought to replace them with VRC-125s. While it is not known if this replacement occurred, one ACV did receive a VRC-46 radio. The hovercraft carried a Decca 202 radar with a dish antenna, which could detect targets within . Some Army ACVs were fitted with XM3 Personnel Detectors (better known as XM-3 "people sniffers"), which could detect human emissions including carbon and ammonia. This equipment was used to find hidden enemies. Dog teams were also sometimes carried to help detect enemies. The radar was found to be very effective, including for navigating in low-visibility and foggy conditions. The PACV was armed with twin .50 caliber M2 Browning machine guns in a roof-mounted turret in the front and two 7.62mm M60 machine guns, one port and one starboard. The Army initially equipped their hovercraft with a minigun and 40 mm M5 automatic grenade launcher as well. Only one ACV was outfitted with a grenade launcher, however, and the miniguns were removed to make space for more troops and cargo