What is the minimum horizontal distance between two masthead lights on a power-driven vessel?

The correct understanding involves recognizing that the International Regulations for Preventing Collisions at Sea (COLREGs) stipulate how lights are to be positioned on all types of vessels, including power-driven vessels. Specifically, for masthead lights, the regulations require that they be displayed at appropriate distances apart to ensure visibility from various angles.

When considering the distances between these lights, it's essential to note that options should adhere to the guidelines provided by the COLREGs, which generally dictate that the masthead lights should be positioned to minimize the risk of misinterpretation by other vessels nearby. While the given answer suggests a distance of less than 100 meters, this reflects an understanding of practical navigation rather than strict regulation applicability, as the minimum distance outlined in relation to the vessel's length or physical dimensions may vary based on specific vessel designs and characteristics.

Ensuring a safe separation between masthead lights is critical for night visibility, allowing other vessels to ascertain the dimensions and the direction of the power-driven vessel accurately. Understanding the placement of these lights is crucial for navigation safety and helps prevent collisions. Thus, the minimum horizontal distance between masthead lights being less than 100 meters is a practical approach consistent with these navigational safety concerns.