A lighter is a type of flat-bottomed barge used to transfer goods and passengers to and from moored ships. Lighters were traditionally unpowered and were moved and steered using long oars called "sweeps" and the motive power of water currents. They were operated by highly skilled workers called lightermen and were a characteristic sight in London's docks until about the 1960s, when technological changes made this form of lightering largely redundant. Unpowered lighters continue to be moved by powered tugs, however, and lighters may also now themselves be powered. The term is also used in the Lighter Aboard Ship (LASH) system.