lightships

Lightships, or light vessels, are ships that function as navigational aids at sea by carrying a powerful light and often a fog signal to mark hazardous areas, channels, or harbor approaches where building a traditional lighthouse is impractical. They are normally anchored or moored at a fixed position and maintained to operate as stationary lighthouses, providing a visual and audible reference for mariners in offshore locations such as sandbanks, shoals, river mouths, or coastal approaches.

History and deployment: The idea of floating beacons developed to extend navigational guidance beyond land-based lighthouses. From the 18th through the 20th centuries, many civil and naval authorities operated networks of lightships along busy sea routes and coastlines where permanent lighthouses could not be easily placed. They played a crucial role in safe passage before modern offshore infrastructures and automated aids reduced their necessity.

Design and equipment: Lightships are designed to withstand harsh sea conditions and are typically heavy vessels fitted with a fixed anchoring arrangement. They carry a high-intensity lantern, often with Fresnel lenses, and may include rotating beacons and fog signals such as bells, horns, or sirens. Power sources evolved from coal or oil to diesel generators and electric systems, with some stations equipped for solar power in later years. Many lightships also served as weather observation platforms and host to radio beacons.

Operation and legacy: The advent of offshore platforms, automated buoys, and advanced electronic navigation led to the retirement or conversion of many lightships. A number remain as museum ships or preserved vessels, and a few offshore lightships still serve as temporary aids or backups. Notable examples include the Nantucket Lightship off Massachusetts and the Chesapeake Lightship in Chesapeake Bay.