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lightship,moored vessel bearing lights and other signal devices to guide ships and warn of hazards to navigation. Lightships are generally stationed at points where a lighthouse cannot be erected; they are given distinctive features (e.g., high bows, special coloring) so as to be readily distinguishable from other vessels, and they have strong hulls, able to withstand consistent pressures. The first lightship in the United States was posted in 1820 (in the Elizabeth River, near Norfolk, Va.). Afterward, for a time, lightships proliferated; but their number has steadily decreased since the end of World War I. They are costly to staff and maintain, and various engineering developments, such as the construction of large radio buoys, have helped to reduce the need for them. Shortly before World War II all U.S. lightships were placed under the control of the U.S. Coast Guard.
A distinctively marked vessel anchored or moored at a charted point, to serve as an aid to navigation.
a ship equipped as a lighthouse and moored where a fixed structure would prove impracticable