Load line (watercraft)

In the same way, fresh water is less dense than salinated or seawater, with a similar lessening effect upon buoyancy.

In the case of Venice this was a cross marked on the side of the ship,[5][6] and of Genoa three horizontal lines.

[7] The first 19th-century loading recommendations were introduced by Lloyd's Register in 1835, following discussions among shipowners, shippers and underwriters.

In the 1860s, after increased loss of ships due to overloading, a British MP, Samuel Plimsoll, took up the load line cause against strong opposition.

In 1906, laws were passed requiring foreign ships visiting British ports to be marked with a load line.

In 1966 the International Convention on Load Lines was concluded in London which re-examined and amended the 1930 rules.

[9] The original "Plimsoll mark" was a circle with a horizontal line through it to show the maximum draft of a ship.

Additional marks have been added over the years, allowing for different water densities and expected sea conditions.

Letters may also appear to the sides of the mark indicating the classification society that has surveyed the vessel's load line.

The initials used include AB for the American Bureau of Shipping, BV for Bureau Veritas, VL for DNV GL, IR for the Indian Register of Shipping, LR for Lloyd's Register, NK for Nippon Kaiji Kyokai and RI for the Registro Italiano Navale.