The RNLI has an active fleet of over 330 lifeboats, ranging from 3.8–17m in length, as well as a relief fleet. There are also four active and three relief hovercraft.
Different classes of lifeboat are needed for various locations, depending on geographical features, the kind of rescue work that the station is asked to do and the cover provided by neighbouring stations. So RNLI lifeboats are divided into two categories: all-weather and inshore.
All-weather lifeboats (ALBs) are capable of high speed and can be operated safely in all weather. They are inherently self-righting after a capsize and fitted with navigation, location and communication equipment.
Inshore lifeboats (ILBs) usually operate closer to shore than ALBs, in shallower water, close to cliffs, among rocks or even in caves.
Hovercraft can operate in areas such as mud flats or river estuaries that are inaccessible to conventional lifeboats.