BOTH INTERNATIONAL & INLAND Which of the following describes a vessel exhibiting the day-shapes shown in illustration D018RR below?

Correct Answer: Option A — dredging

Rule 27(d) of the COLREGS mandates that a vessel engaged in dredging or underwater operations, when restricted in her ability to maneuver, must display two black balls in a vertical line to indicate the side of obstruction and two diamonds to indicate the side on which passing is safe.