What light is required on vessels of less than 50 meters in length?

Vessels less than 50 meters in length are required to display one anchor light when at anchor. The anchor light is important for identifying the vessel's position to other mariners during nighttime or low-visibility situations, ensuring safety and preventing collisions. This light should be positioned to be visible all around the horizon, typically set at the highest point on the vessel.

The requirement for just one anchor light aligns with regulations in the International Regulations for Preventing Collisions at Sea (COLREGs), which are followed by vessels worldwide. This simplifies requirements for smaller vessels, allowing for easier compliance while maintaining essential safety measures.

Other options, such as requiring two anchor lights or no lights at all, do not align with these regulations, as two lights could be misinterpreted as a larger vessel, and no lights would leave the vessel invisible to others, significantly increasing the risk of accidents. Additionally, solely carrying a whistle is insufficient as it does not fulfill the visibility requirement for a vessel at anchor.