Lightship

Lightship Finngrundet, now a museum ship in Stockholm. The day markers can be seen on the masts.
Fehmarnbelt Lightship, now a museum ship in Lübeck
Bürgermeister O´Swald II was the world's largest manned lightship, the last lightship at position Elbe 1. In the picture on a visit to Ystad 12 July 2017.

A lightvessel, or lightship, is a ship that acts as a lighthouse. They are used in waters that are too deep or otherwise unsuitable for lighthouse construction.[1] Although some records exist of fire beacons being placed on ships in Roman times, the first modern lightvessel was located off the Nore sandbank at the mouth of the River Thames in London, England, and placed there by its inventor Robert Hamblin in 1734. Lightships have since become largely obsolete; being largely replaced by lighthouses as construction techniques advanced, and by large automated navigation buoys.[1]

  1. ^ a b Flint, Willard (1993). A History of U.S. Lightships (PDF). United States Coast Guard. Retrieved 2008-07-18.