A Plimsoll line or mark shows the safe 'freeboard' (distance from water to weather deck). There are 6 load lines as follows:
List of Load Lines
| TF | Tropical Fresh
|
| F | Fresh |
| T | Tropical |
| S | Summer |
| W | Winter |
| WNA | Winter North Atlantic
|
Example Plimsoll Line or Mark
* AB - This is the clasification society that surveyed the vessel in order to determine her marks. AB stands for American Bureau.
The world is divided into "load line zones" which correspond to the Plimsoll Line. A vessel running through a winter load line zone is only permitted to load down to her W mark. Ships of LOA (Length Overall) have further restrictions when running through the WNA zone.
The following should give you an idea of how the world is divided up into the 6 zones:
