was a lengthened engine cowling that enclosed the exhaust collector ring. Amongst the modifications needed was for the aircraft to be convertible to a seaplane configuration, thus the prototype was overhauled and outfitted with twin floats equipped with shock absorbers. In this configuration, early test flights were conducted at Brough during April 1935; a successful series of sea trials took place at the Marine Aircraft Experimental Establishment Felixstowe. Blackburn was issued contract No. 334315/34 in conjunction with the new Specification 13/35. I, along with the additional contract No. 510994/35 to Specification 19/36, which was issued in January 1937. Even more contracts soon followed, leading to the rate of production exceeding that of numerous preceding Blackburn aircraft. During a three-year production run, a total of 238 Sharks were delivered to the FAA, comprising 16 Mk I (Tiger IV), 126 Mk II (760 hp/567 kW Tiger VI) and 95 Mk III (760 hp/570 kW Tiger VI). The Shark III differed from prior models in several respects, the most apparent of which was the addition of a glazed cockpit canopy and three-bladed Rotol wooden propellers. Late on in production, assembly from components produced elsewhere took place at Blackburn's new factory in Dumbarton, Scotland, after which the completed airframes were transported by road to the Clyde for flight testing. Operational history Fleet Air Arm During May 1935, the Shark entered service with 820 Naval Air Squadron, replacing its Fairey Seals, aboard HMS Courageous. During the following year, it also equipping an additional two squadrons, 810 and 821. The FAA opted to actively deploy the Shark both in its landplane configuration on board the Royal Navy's aircraft carriers and as a seaplane on its battlecruisers, such as HMS Warspite and HMS Repulse; in the latter capacity, it would either be catapult-launched or lowered over the side to take off from the water, dependent on available equipment. Its seaworthiness was a particular point of praise, possessing favourable rough water handling and buoyancy characteristics. Frontline operations involving the Shark were curtailed after only a relatively short timespan, as the type had started to be replaced by the more capable Fairey Swordfish as early as 1937. However, its value in secondary roles meant that it continued to be operated for numerous years beyond this point; a considerable number of Shark IIs were operated by the B and C training flights at Lee-on-Solent. 20 Sharks were converted by Blackburn