Submersible

A submersible is an underwater craft which needs to be transported and supported by a surface vessel or platform. This distinguishes submersibles from submarines, which are self-supporting and capable of independent operation. There are many types of submersibles, including both human-occupied vehicles (HOVs) and uncrewed craft, variously known as remotely operated vehicles (ROVs) or unmanned underwater vehicles (UUVs). Submersibles have many uses including oceanography, underwater archaeology, ocean exploration, adventure, equipment maintenance and recovery, and underwater videography. Submarine#History The first recorded self-propelled underwater vessel was a small oar-powered submarine conceived by William Bourne (c. 1535–1582) and designed and built by Dutch inventor Cornelis Drebbel in 1620, with two more improved versions built in the following four years. Contemporary accounts state that the final model was demonstrated to King James I in person, who may even have been taken aboard for a test dive. There do not appear to have been any further recorded submersibles until Bushnell's Turtle. The first submersible to be used in war was designed and built by American inventor David Bushnell in 1775 as a means to attach explosive charges to enemy ships during the American Revolutionary War. The device, dubbed Bushnell's Turtle, was an oval-shaped vessel of wood and brass. It had tanks that were filled with water to make it dive and then emptied with the help of a hand pump to make it return to the surface. The operator used two hand-cranked propellers to move vertically or laterally under the water. The vehicle had small glass windows on top and naturally luminescent wood affixed to its instruments so that they could be read in the dark. Bushnell's Turtle was first set into action on September 7, 1776, at New York Harbor to attack the British flagship . Sergeant Ezra Lee operated the vehicle at that time. Lee successfully brought Turtle against the underside of Eagles hull but failed to attach the charge because of the strong water currents.