What lights and shapes indicate the obstructed side of a vessel engaged in dredging or underwater operations?

The presence of two all-around red lights and two black balls is indicative of the obstructed side of a vessel engaged in dredging or underwater operations. This specific configuration serves to alert other vessels to the fact that the dredging vessel has a side that is obstructed and poses a hazard. The two all-around red lights signify that the vessel is restricted in its ability to maneuver, while the two black balls denote the side that is obstructed.

This signaling is in alignment with the International Regulations for Preventing Collisions at Sea (COLREGs), which require vessels carrying out such operations to clearly indicate their status to ensure safety and awareness among nearby vessels. The use of these specific lights and shapes communicates effectively to mariners that caution is necessary when navigating near the dredging vessel, highlighting both the position of the vessel and the potential hazard.