United States Coast Guard Captains License Practice Exam 2025 - Free Captains License Practice Questions and Study Guide

Law enforcement vessels are permitted to display a flashing blue light, which serves as a distinctive signal to identify themselves as vessels of authority. This blue light is widely recognized and ensures that other vessels in the vicinity are aware that they are dealing with a law enforcement agency. The use of a flashing blue light helps facilitate compliance with various maritime regulations and allows for more effective enforcement of maritime laws.

The other lighting options do not carry the same recognition or authority in a law enforcement context. For example, two red lights in a vertical line typically signify a vessel engaged in fishing or other specific activities. A flashing yellow light is often utilized to indicate caution or warning but doesn't denote an enforcement capability. A green light, combined with a masthead light, is typically used to indicate the starboard side of a vessel, primarily for navigation rather than indicating law enforcement status.