What is the minimum length for a power-driven vessel to be required to exhibit two masthead lights?

A power-driven vessel must exhibit two masthead lights when its length is 50 metres or more. The requirement is outlined in the COLREGs (International Regulations for Preventing Collisions at Sea), specifically focusing on the proper display of lights to ensure visibility and safety at sea.

The rationale behind this requirement is based on the increased size and operational capabilities of vessels that are 50 metres and longer. Such vessels may be involved in various maritime activities and require enhanced visibility to other vessels, especially during periods of reduced visibility or bad weather. The two masthead lights indicate the presence and direction of a large power-driven vessel, allowing other mariners to assess its size and navigation path more effectively.

For vessels under 50 metres, one masthead light is typically sufficient to provide appropriate visibility and communication about the vessel’s intentions. This graduated lighting requirement ensures a balance between safety at sea and the practicality of maintaining proper navigation lighting.