Plimsoll Line
F5. The Reference Layer: Glossary, Units, Signals and Information SourcesDefinition
Load-line mark on the hull side, named after Samuel Plimsoll.
The Plimsoll line, or load line, is the hull-side mark showing the maximum legal loading draft, with the centerline disc and the seasonal lines (S, W, WNA, T, F, TF) referenced to it. It is named after Samuel Plimsoll, whose campaign led to the UK Merchant Shipping Act 1876. The marks are now governed by the International Convention on Load Lines, 1966, and verified on the International Load Line Certificate. The summer mark fixes the freeboard and thus the deadweight.