Load line is a special marking positioned amidships of the vessels which depicts the draft of the vessel and the maximum permitted limit in distinct types of waters to which the ship can be loaded.
S = Summer, W = Winter, T = Tropical, F = Fresh water and TF = Tropical Freshwater.
It influence the cargo intake of a vessel and the different zones changes during a year as described in the table below and in the load line map of Maritime Optima.
In the 1966 Load Lines convention, adopted by IMO, provisions are made determining the freeboard of ships by subdivision and damage stability calculations. The regulations take into account the potential hazards present in different zones and different seasons.
The International Navigating Limits (INL), formerly Institute Warranty Limits (IWL), were revised and renamed by the Institute of Chartered Underwriters in London, United Kingdom, in 2000 and became effective in November 2003.
The term IWL is still found in charter parties and related documents and should be updated to refer to INL because there are significant changes in some areas.
The lWL zones are:
You can check different zones in the Load Line Map layer in Maritime Optima:
If you point at the different areas, you will find the information from the table above applicable for each area:
You can study the INL zones in this article:
You can always create a free user account in Maritime Optima. The application is available in AppStore, Google Play Store and on your computer (in the browser):