COLREGs in context...

During the age of sail, the mindset of maritime nations was that ships moved slowly. However, with the advent of steam-powered vessels in the mid-19th century, vessels could manoeuvre at will irrespective of wind direction and wind velocity. Add to this the lack of international agreement on regulations to avoid collisions at sea, inconsistencies and contradictions meant collisions at sea were frequent.

The U.S. Congress addressed steamboat safety as part of an act in 1838 and determined that steamboats, running between sunset and sunrise, had to display one or more signal lights, but the colour, visibility, and location were not specified.

The UK Parliament passed the Steam Navigation Act of 1846, this law required that steam vessels pass port-to-port, that crossing vessels make course alterations to starboard, and that sailing vessels on the port tack give way to vessels on the starboard tack. Then two years later the UK issued regulations requiring steam vessels to display red and green sidelights, as well as a white masthead light. This in turn influenced the U.S. and in 1858 both the U.S. and the UK recommended the coloured sidelights for sailing vessels as well and fog signals also came into play.

Further countries began to adopt these new rules in the years to follow and more international regulations came into play. In 1867 Thomas Gray, the assistant secretary to the Maritime Department of the British Board of Trade wrote a document called “The Rule of the Road”, which became famous for its mnemonic verses such as:

Two Steam Ships meeting:

When both side-lights you see ahead Port your helm and show your RED.

Two Steam Ships passing:

GREEN to GREEN or, RED to RED Perfect safety go ahead!

However, it was the 1912 disaster of the Titanic that pushed the formalisation of the International Convention for the Safety of Life at Sea (SOLAS) and created worldwide awareness of the need for international harmonisation of maritime regulations.

The worldwide, harmonised collision regulations that are used for safe passage today, were first introduced by the International Maritime Organization 1972 for ratification by member states. On 15 July 1977 the International Rules for Preventing Collisions at Sea, more commonly known as COLREGs, entered into force and became the rule of law.