In restricted visibility, a vessel detected by radar alone shall determine if a close-quarters situation is developing or risk of collision exists. If so, you shall:

• A. Turn toward the other vessel
• B. Increase speed to pass
• C. Avoid altering course toward a vessel abaft the beam
• D. Hold course and speed

Answer: (C)

In restricted visibility, you must use radar to determine whether a close-quarters situation or risk of collision is developing, and if it is, take early action to avoid a collision. The safest move when a risk exists is to avoid altering course toward a vessel abaft the beam. Turning toward a vessel behind you can bring you into a tighter or uncertain path, increasing the chance of collision, so you should steer away from the other vessel or adjust your speed to gain safer separation. The other options either move you closer to danger (turning toward the other vessel), fail to reduce risk (holding course and speed), or could worsen the situation (increasing speed to pass without ensuring safe clearance).