What is the minimum length of a power-driven vessel that must show forward and after masthead lights?

The minimum length for a power-driven vessel to be required to show both forward and after masthead lights is 50 meters. This requirement is outlined in the International Regulations for Preventing Collisions at Sea (COLREGs), which establishes rules for the navigation of vessels to ensure safety at sea.

For vessels shorter than 50 meters, there are simplified light requirements because they are generally considered to be of a size where the risk of collisions is lower, or they may operate in conditions where their visibility needs differ. Power-driven vessels that are 50 meters or longer must display two masthead lights to enhance their visibility and indicate their length and heading, contributing to a clearer understanding of their navigation by other vessels.

This regulation aims to reduce the risk of collisions by ensuring that larger vessels, which can pose significant dangers due to their speed and size, provide adequate warning of their presence.