LIFEBOAT

watercraft especially built for rescue missions. There are two types, the relatively simple versions carried on board ships and the larger, more complex craft based on shore. Modern shore-based lifeboats are generally about 4050 feet (1215 metres) long and are designed to stay afloat under severe sea conditions. Sturdiness of construction, self-righting ability, reserve buoyancy, and manoeuvrability in surf, especially in reversing direction, are prime characteristics. As early as the 18th century, attempts were made in France and England to build unsinkable lifeboats. After a tragic shipwreck in 1789 at the mouth of the Tyne, a lifeboat was designed and built at Newcastle that would right itself when capsized and would retain its buoyancy when nearly filled with water. Named the Original, the double-ended, ten-oared craft remained in service for 40 years and became the prototype for other lifeboats. In 1807 the first practical line-throwing device was invented. In 1890 the first mechanically powered, land-based lifeboat was launched, equipped with a steam engine; in 1904 the gasoline engine was introduced, and a few years later the diesel. A typical modern land-based lifeboat is either steel-hulled or of double-skin, heavy timber construction; diesel powered; and equipped with radio, radar, and other electronic gear. It is manned by a crew of about seven, most of whom are usually volunteers who can be summoned quickly in an emergency.