If a deep draughted vessel exhibiting NUC lights is on your port side, what should your action be?

When observing a deep draughted vessel exhibiting NUC (Not Under Command) lights on your port side, the appropriate action is to reduce speed and allow that vessel to pass ahead. This is primarily because a deep draughted vessel may have limited maneuverability and is unable to comply with the normal navigation rules. By reducing speed, you provide the vessel with the necessary space and time to navigate safely, acknowledging its inability to maneuver effectively.

Maintaining speed or increasing speed could pose a risk of collision, particularly in confined waters or where the deep draughted vessel's draft might lead to grounding in shallower areas. Changing course to starboard may potentially put your vessel in a position that obstructs the path of the deep draughted vessel, which is not advisable given its restricted ability to maneuver.

Overall, reducing your vessel's speed allows for a safe passage and shows consideration for the limitations of the other vessel's navigation capabilities, in keeping with the intentions behind the COLREGs.