Plimsoll Day

Plimsoll Day is an annual American observance dedicated to Plimsoll lines. This innovation greatly improved ship safety, helping to prevent vessels from sinking due to overloading. The holiday is celebrated each year on February 10.

History

Before the Plimsoll line, numerous ships were lost at sea due to overloading or improper distribution of cargo. Sometimes, shifting cargo caused ships to list and eventually capsize.

Samuel Plimsoll, an English politician and reformer, decided to tackle these problems. After losing a significant investment when a coal ship sank in 1853, he began studying maritime safety. By the late 19th century, he championed shipping reforms, including the introduction of Plimsoll lines—marks indicating the maximum legal draft, or depth, to which a ship may be safely loaded.

Today, the use of the Plimsoll line is a global safety standard for cargo ships, greatly reducing the risks of capsizing and sinking.

Interesting Facts

• The term “Plimsoll line” is now often replaced with “waterline,” but it refers to the same marking on a ship’s hull.
• The marks on a ship’s side are set for both freshwater and seawater. Because the density of seawater is higher than that of freshwater, a vessel will float differently in each.

How to Take Part

On Plimsoll Day, take a moment to learn about the history and importance of Plimsoll lines. Read up on international standards for ship loading and safety, and share your knowledge with others.

Spread the word about Plimsoll Day on social media. Ask your friends if they know what a Plimsoll line is!

When is Plimsoll Day in 2026?

Plimsoll Day is observed on February 10 each year.

Observations