BOTH INTERNATIONAL & INLAND You are approaching a vessel dredging during the day and see two balls in a vertical line on the port side of the dredge. What do these shapes indicate?

Correct Answer: Option C — there is an obstruction on the port side of the dredge

Rule 27(d)(ii) states that a vessel engaged in dredging or underwater operations shall display two balls in a vertical line to indicate the side on which the obstruction exists. This informs other vessels that they must avoid the side displaying the shapes to prevent grounding or collision.