Vessels Light vessels came into use in the 1700s. Most light vessels were about 120 feet in length with a 25-foot beam. These ships, fully loaded weighed anywhere between 190 and 560 tons. Light vessels are basically ships with lighthouses on top. Light Buoys Similar to lighthouses, buoys float on the water and produce fixed or occulting lights.
Some buoys use bells or whistles in addition to lights.
These were the earliest fog signals. Unfortunately, they were also inefficient. Explosives Gunpowder, guns and rockets were used even into the 20th century to make a loud report as a fog signal. Data derived and compiled primarily from the Encyclopaedia Britannica, 1961.