At 17 metres long, the Severn-class lifeboats are the largest class of UK lifeboat.
A boat is a watercraft of a large range of sizes designed to float, plane, work or travel on water. Small boats are typically found on inland waterways (e.g., rivers and lakes) or in protected coastal areas. However, boats such as the whaleboat were designed for operation from a ship in an offshore environment. In naval terms, a boat is a vessel small enough to be carried aboard another vessel (a ship). Another less restrictive definition is a vessel that can be lifted out of the water. Some definitions do not make a distinction in size, as bulk freighters 1,000 feet (300 m) long on the Great Lakes are called oreboats. For reasons of naval tradition, submarines are usually referred to as ‚boats’ rather than ‚ships’, regardless of their size and shape. Ships are generally distinguished from boats based on their larger size, shape and cargo or passenger capacity.
Boats have a wide variety of shapes, sizes and construction methods due to their intended purpose, available materials or local traditions. Canoe-type boats have been used since prehistoric times and various versions are used throughout the world for transportation, fishing or sport. Fishing boats vary widely in style partly to match local conditions. Pleasure boats include ski boats, pontoon boats, and sailboats. House boats may be used for vacationing or long-term housing. Small boats can provide transport or convey cargo (lightering) to and from large ships. Lifeboats have rescue and safety functions. Boats can be powered by human power (e.g., rowboats), wind power (e.g., sailboats) and motor power (e.g., propellor-driven motorboats driven by gasoline or diesel engines).