🔍 Key Concepts

• Inland Navigation Rules – Rule 27 (Vessels Restricted in Their Ability to Maneuver), including examples such as dredging, underwater operations, and underway replenishment • Meaning of a vertical red–white–red light configuration and what additional side lights (pairs of red or green) usually indicate in dredging or underwater work • Difference between special Navy signals (aircraft carrier flight operations, submarine operations) and the more common inland construction/dredging signals

💭 Think About

• First, look closely at the central group of lights in the illustration: what does a vertical stack of red over white over red usually tell you about the vessel’s status? • Next, examine the pairs of green and red lights to either side of that central group: on dredges or similar vessels, which color marks the safe side to pass, and which marks the obstructed side? • Compare what you see in the picture to what you would expect from an aircraft carrier or submarine – would those normally be operating close to river banks with pairs of fixed lights along the sides?

✅ Before You Answer

• Verify that you recognize red–white–red (vertical) as the standard lights for a vessel restricted in her ability to maneuver (RAM) under Rule 27. • Confirm which color pair (two green vs. two red) indicates the side on which another vessel may pass when a dredge or obstruction is present. • Check whether any of the listed options actually match a RAM dredging/underwater operation pattern; if not, consider whether "None of the above" might be appropriate.