What is the lowest line on a load line tree?

The lowest line on a load line tree is designated as WNA (Winter North America). Load line markings, often referred to as Plimsoll marks, indicate the maximum depth to which a ship may be safely loaded, allowing for considerations of stability and ensuring that vessels can navigate safely under varying conditions.

The WNA line specifically represents the maximum load for a vessel operating in cold water during winter months in North America, where the maritime conditions can be particularly challenging due to factors such as temperature and ice.

Other lines represent different loading conditions for varied environmental scenarios, with the B (Ballast) and S (Summer) lines indicating different loading situations depending on the season. The T (Tropical) line is also representative of safe loading conditions for warmer waters. However, in terms of height on the load line tree, WNA is positioned at the lowest point, signifying the most conservative loading amount to mitigate risk in colder conditions.