COLREGs Lights & Shapes Practice Test 2026 - Free Maritime Navigation Practice Questions and Guide

A vessel engaged in purse seining displays two yellow lights in a vertical line that flash alternately every second. This specific configuration of lights serves to indicate to other vessels that the fishing activity is taking place. The use of yellow lights is critical as it distinguishes this particular activity from other types of fishing or vessel operations.

The choice of displaying lights in a vertical arrangement and their alternating flashing pattern is an important safety measure. It alerts nearby vessels to approach with caution, as purse seining can involve significant gear spread and operational activities that might pose navigation hazards. Recognizing these lights ensures that other vessels maintain a safe distance while allowing the purse seiner to operate effectively.

In contrast, other light configurations, such as red lights or green lights, do not denote this specific fishing operation and instead may indicate different statuses or activities that do not involve purse seining. Each color and arrangement of lights plays a vital role in maintaining navigational safety at sea, ensuring that vessels can communicate their activities effectively to others in their vicinity.