🔍 Key Concepts

• Rule 20-21 – Lights and shapes (COLREGS/Navigation Rules): know the color and sectors of sidelights and masthead/stern lights • Relative bearing from YOUR vessel: you are heading due north and the target is one point (11.25°) on your port bow • What combination of lights (two white + one green) means about where you are seeing the other vessel (ahead, on the beam, or abaft the beam)

💭 Think About

• First identify which lights you are seeing: which are sidelights and which are masthead or stern lights based on color and relative position in the picture • Decide whether you are looking at the other vessel’s starboard side, port side, or its stern, using the green light and the arrangement of the whites • From that relative position, sketch a simple compass rose and figure out which heading of the other vessel would place its starboard side where you see it while you are heading due north

✅ Before You Answer

• Verify the arcs of visibility: sidelights show from dead ahead to 22.5° abaft the beam; stern light shows 135° centered astern; masthead light shows 225° from right ahead to 22.5° abaft the beam • Make sure you understand that green = starboard sidelight, red = port sidelight, and white(s) are masthead/stern lights on a power-driven vessel • Before picking a choice, confirm: are you seeing the starboard bow, starboard beam, or stern of the other vessel? The direction of travel must match that viewpoint.