A C-class lifeboat usually refers to the Zodiac Grand Raid Mark IVs lifeboats, powered by twin 40 hp outboard motors, manufactured by Zodiac Marine & Pool of France, and which were operated by the Royal National Lifeboat Institution.

They were initially designated as D-class lifeboats, starting a series of boats numbered from D-500, but this was subsequently changed to C-class, to signify the difference between the twin engine C-class and the single engine D-class.

[1] In 1970, the first lifeboats to be classed as C-class were twin engine RIBs, which were developed to be the Atlantic series lifeboats, and were re-designated B-Class.

C-1 was renumbered as B-3, C-2 became B-4 etc.

[1] The C-class Zodiac Grand Raid IV was replaced by both the D-class (EA16) and the B-class (Atlantic 21) inshore lifeboats.