The patrol boats had a displacement of 100 tons at standard load and 146 tons at full load, were in length overall, had a beam of , and draughts of at standard load, and at full load. Propulsion machinery consisted of two 16-cylinder Paxman YJCM diesel engines, which supplied to the two propellers. The vessels could achieve a top speed of , and had a range of at . The ship's company consisted of three officers and sixteen sailors. Main armament was a bow-mounted Bofors 40 mm gun, supplemented by two .50 calibre M2 Browning machine guns and various small arms. The ships were designed with as many commercial components as possible: the "Attack"s were to operate in remote regions of Australia and New Guinea, and a town's hardware store would be more accessible than home base in a mechanical emergency.