Which British fighter was tested with Shark floats?

Besides its main role as a carrier-based fighter, the Roc had to be able to operate as a float seaplane. A conversion kit was designed that allowed a set of floats taken from a Blackburn Shark to be fitted to it. These floats, largely built of Alclad, carried water rudders operated pneumatically and connected directly to the aircraft's conventional brake system; the tailwheel was replaced by a mooring ring.

During trials, the first conversion showed directional instability and crashed in December 1939 at the Marine Aircraft Experimental Establishment at Helensburgh, to which it had been moved on the outbreak of war. Testing continued with the other conversion, with particular effort put into correcting that instability. Adding an enlarged ventral fin largely solved the problem, but the floats' effect on performance was too great to ignore, since the top speed had fallen to just 193 mph (168 kn; 311 km/h).

For that reason, plans to form a fighter squadron equipped with the floatplane Roc were abandoned. In 1942 the floatplane Roc was evaluated again to see if it could be useful as a fleet target tug, to replace the floatplane Sharks used in that role.