NUC / RAM / Constrained by Draft Practice Questions

1. A vessel not under command (NUC) shall show:

• A.One all-round red light and a flashing white light
• B.Two all-round white lights in a vertical line
• C.An all-round red light over an all-round white light
• D.Two all-round red lights in a vertical line and, when making way, sidelights and sternlight✓

Why: Rule 27(a) prescribes two all-round red lights in a vertical line for a NUC vessel. When making way, she adds sidelights and a sternlight. Red over red — not white — is the critical identifier distinguishing NUC from fishing (red over white) or RAM (red-white-red).

2. A vessel restricted in her ability to maneuver (RAM) shall show which all-round lights?

• A.Red over red — two lights in a vertical line
• B.Green over white — two lights in a vertical line
• C.Red, white, red — three lights in a vertical line✓
• D.White, red, white — three lights in a vertical line

Why: Rule 27(b)(i) requires a RAM vessel to show three all-round lights in a vertical line: the uppermost and lowest lights red, and the middle light white. The mnemonic 'red-white-red' (or a ball-diamond-ball shape by day) signals restricted maneuverability.

3. You observe a vessel at night showing red-white-red all-round lights in a vertical line, two masthead lights, sidelights, and a sternlight. What is this vessel?

• A.A vessel not under command making way
• B.A vessel engaged in dredging or underwater operations making way
• C.A vessel restricted in ability to maneuver and making way✓
• D.A vessel constrained by her draft

Why: Red-white-red vertical lights identify a RAM vessel. The additional masthead lights, sidelights, and sternlight indicate she is underway and making way. A NUC vessel would show red over red, not red-white-red.

4. A vessel engaged in minesweeping operations shall show, in addition to the lights prescribed for a power-driven vessel underway:

• A.One all-round green light at the masthead and one at each end of the sweep
• B.Three all-round green lights or three black balls — one at the masthead and one at each end of the sweep✓
• C.Two all-round green lights in a vertical line
• D.A yellow flashing light

Why: Under COLREGS/Inland Rule 27(f) (33 CFR 83.27(f)), a vessel engaged in mine clearance operations exhibits, in addition to power-driven-underway lights, three all-round green lights or three balls — one near the foremast head and one at each end of the fore yard — signaling that it is dangerous to approach within 1000 metres. Only option B states the correct count (three green lights / three balls); one green light, two vertical green lights, and a yellow flashing light are not the mine-clearance signal.

5. By day, a vessel not under command shall display:

• A.A black cylinder
• B.Ball, diamond, ball in a vertical line
• C.A single black cone, apex up
• D.Two black balls in a vertical line✓

Why: Rule 27(a)(ii) requires a NUC vessel to show two black balls in a vertical line by day — the daytime equivalent of the two all-round red lights. Two balls means 'helpless'; three balls means 'at anchor.'