A B-class lifeboat is any of a series of inflatable boats operated by the Royal National Lifeboat Institution (RNLI):

Boats in this series include:

Atlantic 21-class lifeboat, the first generation RIB operated by the RNLI
Atlantic 75-class lifeboat, the second generation RIB operated by the RNLI
Atlantic 85-class lifeboat, the third generation & current production model RIB operated by the RNLI

Operational fleet
All-weather lifeboats	Mersey Severn Shannon Tamar Trent
Inshore lifeboats	B-class: Atlantic 85 D-class: IB1 E-class: Mark II Mark III H-class (Hovercraft)
Small inflatables	Arancia X-class XP-class Y-class

Historic lifeboats

Pulling and sailing lifeboats

All-weather motor lifeboats

Up to 10 knots	35ft 6in Self-righting Barnett Beach Liverpool Norfolk and Suffolk Oakley Ramsgate Rother Solent Steam Surf Watson
Above 10 knots	Arun Brede Clyde Thames Tyne Waveney

Inshore lifeboats

Experimental lifeboats