The load line is a special marking positioned amidships of the vessels which depict the draft of the vessel and the maximum permitted limit in distinct types of waters to which the ship can be loaded.

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S = Summer, W = Winter, T = Tropical, F = Fresh water and TF = Tropical Freshwater.

It influences 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. You will find the Load line zones in "styles and layers":

You find the layers on your mobile as well. Click on the map and find info about the different zones. Some of them change with the season.