What is the purpose of load lines in ships?
Load line indicates the maximum depths to which vessels can be submerged in different situations and seasons ie these lines show the maximum cargo a ship can carry according to International Load line regulations.
In order to avoid port fees that might be charged based on the vessel’s deadweight, Some shipowners choose to have multiple load lines on their ships. In that case, ship manager need to gets in contact with class to activate the appropriate Load line certificate and vsl needs to mark/paint the plimsoll line on vessel’s hull.
Load lines are used to indicate the level to which a ship may be safely loaded, ensuring the vessel’s stability and preventing damage. The principle of reserve buoyancy and freeboard were established in the first International Convention on Load Lines in 1930.
The 1966 Load Lines convention introduced new provisions for determining the freeboard of ships using subdivision and damage stability calculations, which take into account various risks and hazards.To ensure the watertight integrity of the ship’s hull, the convention includes safety measures concerning doors, freeing ports, hatchways, and other items.
The ship’s assigned load lines and deck line must be marked amidships on each side. For ships carrying timber deck cargo, a smaller freeboard is assigned because the deck cargo provides protection against wave impacts.
The marking is also known as Plimsoll Mark from a member of the British Parliament, Samuel Plimsoll (1824–1898), who expressed concerns in regard to the loss of ships and crews from vessel overloading.
Load Line Convention may not apply to certain types of vessels, such as:
- new ships of 24 length or less,
- existing ships of less than 150 GT,
- pleasure yachts not engaged in trade and
- fishing vessels.
Also, there are some exemptions by geographical area.