Historical background leading to the adoption of the Load Lines convention
The stability of ships can be seriously affected by overloading, especially if the cargo shifts during the course of the voyage and the practice of marking ships to indicate how low they may safely rest in the water when loaded goes back several centuries. Most merchant ships today are covered by the International Convention on Load Lines, 1966, as amended.
The Load Lines Convention contains detailed regulations on the assignment of the freeboard (the vertical distance between the top of the hull and the waterline) and the specific limitations to which different types of ships may be loaded. Several lines are painted on the ship, above and below the central freeboard line - because ships may be loaded to a greater or lesser degree depending on the zone and season, as potential hazards vary.
lines - history
The first official loading regulations are thought to date back to maritime legislation originating with the island kingdom of Crete in 2,500 BC when vessels were required to pass loading and maintenance inspections.
Roman sea regulations also contained similar regulations.
In the middle ages, the Venetian Republic - which controlled much of the sea trade in the Mediterranean - had laws requiring vessels to be loaded to a maximum depth indicated by a fixed line marked on the side of the hull. Ships from Venice were marked with a cross, while the city of Genoa used three horizontal bars.
Elsewhere, the Hanseatic League, which controlled much of the trade from the Rhine to the eastern and northern Baltic up to the seventeenth century, issued a law in 1288 from the Scandinavian town of Visby, its commercial centre, which required ships to load to a load line or face penalties.
Later, under standard
maritime procedures developed for Baltic Sea at a meeting in Copenhagen in 1561,
a captain could be fined "for overburdening his ship".
But as trade grew, so did the number of ships being lost. Moreover, changing technology -with sails turning to steam and wood being replaced by steel - meant experience in ship design could not always keep pace and sometimes ships were designed with inadequate freeboards.
Lloyd's Register recommended freeboards as a function of the depth of the hold (three inches per foot of depth) and these recommendations, used extensively until 1880, became known as "Lloyd's Rule".
However, the Rule only applied to ships registered with Lloyd's.
Concern in the
United Kingdom about the growing number of ship losses led to the appointment
of a Royal committee which in 1836 cited bad design and improper building -
but not overloading - as contributory factors to the unseaworthiness of ships.
Nonetheless, seafarers themselves had little say in the safety standards aboard what one captain described as a "coffin ship". In fact, until 1871, it was actually illegal for seafarers to refuse to go to sea, even on the grounds that the ship they were sailing on was unseaworthy. In 1866 four successive crews refused to serve on a ship called the Harkaway on the understandable grounds that even at anchor in a calm sea the ship took on more than one metre of water a day. They were sent to prison.
A shipowner from northern England, James Hall, was concerned about the impact on insurance rates of the high number of shipping casualties - losses had doubled in 30 years. Although many shipowners were portrayed as irresponsible, Hall could see the benefits - in terms of lower insurance rates - of getting all shipowners to abide by good practices.
In particular, Hall petitioned the Board of Trade to investigate the large number of ship losses and the Board of Trade inquiry found overloading was one of the factors to blame.
Meanwhile, a coal dealer and liberal Member of Parliament, Samuel Plimsoll, took up the load line cause. Plimsoll began a battle to try and get merchant shipping laws reformed - against stiff opposition from a minority of shipowners.
A Royal commission on Unseaworthy Ships was set up in 1872 and finally the United Kingdom Merchant Shipping Act of 1876 made load lines compulsory. The load line mark included in the legislation - though the position of the line was not fixed by law until 1894 - became known as the "Plimsoll Line": a circle with a horizontal line through the middle.
Figures on ship casualties probably helped to goad the British parliamentarians into action: in the year 1873 4, around the coastline of the United Kingdom, 411 ships sank, with the loss of 506 lives. But this figure only covers the United Kingdom coastline: between 1867 and 1882, loss of life in British vessels alone (and excluding fishing vessels) totalled 33,427 seafarers and 5,987 passengers. Ships lost numbered 16,393.
In 1906, laws were passed requiring foreign ships visiting British ports to be marked with a load line, while a German law of 1903 also issued freeboard regulations, spreading the regulatory net further.
In the United States, American vessels were loaded to a formula based on "inches per foot of depth of hold" until 1917 when the U.S. Shipping Board required adherence to British Board of Trade standards based on a set of calculated freeboard tables.
Load line legislation was introduced in the American congress in 1920 and failed, but a Load Line Act was passed in the United States in 1929.
By that time, there was a proliferation of different freeboard rules in use by various marine administrations and classification societies, which meant there was a lack of global standardization.
Further preparatory work by the major maritime nations of the time resulted in an international conference held in London in 1930 - which adopted the first International Load Line Convention.
The rules adopted at the conference were not based on exact scientific principles - but were essentially a compromise between the various national rules which had been developed previously.
Load Line Convention
The rules covered superstructure evaluations, freeboards and strength standards.
The minimum freeboard was designed to provide a standard of "reserve buoyancy" (the volume of the watertight hull above the load waterline), while the protection of openings in the hull and superstructures, such as hatches, ventilators, airpipes, scuppers, overhead discharges and the access openings in the end bulkhead of superstructures were an important consideration in the assignment of freeboard.
Another major concern was the protection for the crew by consideration of the strength of gangways, guard rails, lifelines and the height of the working platform itself.
freeboard was the basic minimum summer freeboard in salt water. The regulations
divided the world into different geographical/seasonal zones, with different
load lines for each - in recognition of the fact that sea and weather conditions
vary greatly in different sea areas and in different seasons of the year. A
ship sailing in winter in the North Atlantic Ocean had to have an increase in
freeboard while for voyages in the tropical zones and in fresh water there was
a freeboard deduction.
Special rules were provided for tankers and for the carriage of timber deck cargo.
The 1930 load Line Convention was an important step in establishing universally applicable rules.
However, the decades following the adoption of the 1930 Convention saw developments in ship design and methods of construction which began to make the Convention rules look outdated: ships, especially tankers, grew considerably in size; specialized ship designs to meet different trades were becoming prevalent; machinery spaces in dry cargo ships were being located away from the traditional midships position; metal hatchway covers were replacing wooden ones; and welding was replacing riveting.
There was general
agreement that the 1930 Convention needed revision, in particular in the sections
concerning aspects relating to ship design and construction.
In the meantime, the International Maritime Organization had come into being and was clearly the right Organization to host the proposed conference.
Load Lines Convention
Work of the
Like the 1930 Convention,
the 1966 Load Lines Convention sets out rules for calculation and assignment
of freeboard and takes into account the potential hazards present in different
zones and different seasons. The technical annex contains several additional
safety measures concerning doors, freeing ports, hatchways and other items.
The main purpose of these measures is to ensure the watertight integrity of
ships' hulls below the freeboard deck.
The 1966 Convention is made up of:
The 1966 Convention has since been amended, see International Convention on Load Lines
and reserve buoyancy
Type of Vessel
Season and Zone