The Plimsoll Line

Ron examines the development of the Plimsoll lines found on all Merchant Ships

As the Napoleonic wars drew to a close and the Industrial Revolution swept Britain, the British Isles became increasingly dependent on merchant shipping for imports of the raw materials needed to support the thriving industry, and for the export of the products of that industry. Trade with the Empire became of increasing importance.

The Merchant Navy offered adventure, romance, hazard and daring. The adventures of the sea contributed much to literature at that time. There were very few guarantees in those days for the merchant marine and there were very real efforts to improve the safety and the chances of survival of crews and ships. The great rewards enjoyed on the safe arrival of a ship loaded with goods from Asia were matched by the risks of the voyage. Crowds of well-wishers, owners, families and investors cheered the departing ships loaded with valuable cargoes. After the mast-tops disappeared below the horizon nothing would be heard of them for months. There were no undersea cables, no radios to signal the fate of a ship and its crew. The last word of many a ship and men was a posting at Lloyds "Missing presumed lost" their fate unknown.

The danger, the uncertainty and the risks held out promise of rewards that attracted both sailors and investors. In spite of the hazards there was never any shortage of volunteers for the Merchant Navy. Sailors risked their lives in search of adventure and reward and investors risked fortunes on voyages that held perils as great as the potential returns. What crews lacked in amenities, and there were very few, was compensated for by the rewards, it was a period which was the foundation of our concept of the 'romance' of the sea. The spirit of adventure has its limits, however, and by 1836 public concern over the loss of ships and crews reached the point where Parliament appointed a committee to investigate the growing number of shipwrecks. In 1850 legislation was passed to create the Marine Department of the Board of Trade which was to enforce the application of laws governing; manning, crew competence and operation of merchant vessels.

Despite calls for more regulation the British government continued to avoid direct interference with ship operators until, in 1870, Samuel Plimsoll, a member of Parliament from the industrial midlands, demanded creation of a safety limit on loading since it was believed that many ships were lost simply because they were too heavily loaded. The government established a Royal Commission to investigate merchant marine practices and conditions. The Commission exposed many malpractices and bad owners which led to the introduction of a reform bill in 1875, but it was defeated. Public awareness of bad practices and abuses had become widespread however, and the pressure for change became intense. In 1876 the first 'load line' regulations were adopted into law. This required that every ship should be marked with a line such that the ship could only be loaded to the point where the water level reached the line. Because the density of sea water varies according to its temperature and salinity, the point to which the ship is lowered in the water for a given load will vary depending on its location in the world so that it was necessary to have more than one line. Since 1876 all British merchant ships have been required to have these markings on their hull. Samuel Plimsoll (1824 -1898), a politician from Derby, a part of England closer to coal mines and Robin Hood than to the sea, was a driving force behind the legislation and his name lives on in that the load line is referred to as 'The Plimsoll Line'. The position of the load line was not fixed by regulation in the early years and there was considerable variation on how the line was marked on a ship's side.

Until 1917 American vessels were loaded to a formula that was used in Britain before the new regulations came into force. After 1917 the US Shipping Board adopted the British Board of Trade standards for calculations. A Load Line legislation was introduced in Congress in 1920, but it failed to make the Statutes. Not until 1929 was the Load Line Act passed in the United States, more than a century after the problem of ship losses due to overloading had been recognised.

Ron Watts