You are in a TSS overtaking a slower vessel. The vessel ahead is 3 points abaft your starboard beam and you are gradually overtaking. Who has right of way and what action must you take?

A. RULE 13 — OVERTAKING IN TSS: RULE 13(a): "Notwithstanding anything contained in Rules 4 to 18, any vessel overtaking any other shall keep out of the way of the vessel being overtaken." RULE 13(b): "A vessel shall be deemed to be overtaking when coming up with another vessel from a direction more than 22.5 degrees abaft her beam." A vessel 3 points (33.75°) abaft the beam is in the overtaking sector. RULE 13(c): "When a vessel is in any doubt as to whether she is overtaking another, she shall assume that this is the case and act accordingly." YOUR STATUS: YOUR vessel is the OVERTAKING vessel. The vessel ahead is the STAND-ON vessel. You must keep clear. RULE 13(d): "Any subsequent alteration of the bearing between the two vessels shall not make the overtaking vessel a crossing vessel or relieve her of the duty of keeping out of the way of the overtaken vessel until she is finally past and clear." CRITICAL: even if the geometry changes (her speed changes, she manoeuvres) — you remain the overtaking vessel until FINALLY PAST AND CLEAR. You cannot transfer from "overtaking give-way" to "crossing stand-on" mid-manoeuvre. TSS IMPLICATION: Rule 10(j): "Notwithstanding paragraph (b)(ii), a vessel may use an inshore traffic zone when overtaking another vessel where the inshore traffic zone provides a safe passage." TSS rules do not alter the Rule 13 obligation — the overtaking vessel still gives way.

B. When overtaking in a TSS, the rules of the traffic separation scheme take precedence. Vessels in a TSS must maintain course and speed — no overtaking manoeuvres are permitted.

C. Three points abaft the beam is the crossing sector. Apply crossing rules — the vessel on the port side gives way.

D. Overtaking only applies at night when lights can identify the overtaking sector. In daytime, vessels do not have a defined overtaking sector.

A. NUC VESSEL — CM RESPONSE: The vessel displaying TWO BLACK BALLS (day) / TWO ALL-ROUND RED LIGHTS vertical (night) is a NOT UNDER COMMAND (NUC) vessel. COLREG Rule 27(a): "A vessel not under command shall exhibit two all-round red lights in a vertical line where they can best be seen; two balls or similar shapes in a vertical line where they can best be seen." DEFINITION (Rule 3(f)): "Not under command means a vessel which through some exceptional circumstance is unable to manoeuvre as required by these rules and is therefore unable to keep out of the way of another vessel." Typical causes: main engine failure; steering gear failure; loss of power. YOUR OBLIGATIONS: (1) YOUR VESSEL MUST KEEP CLEAR: a NUC vessel cannot take avoiding action. The NUC display is an advisory signal — YOU must manoeuvre. Rule 18(a): "A power-driven vessel underway shall keep out of the way of: a vessel not under command." (2) EARLY AND SUBSTANTIAL ACTION: Rule 16 — "Every vessel which is directed to keep out of the way of another vessel shall, so far as possible, take early and substantial action to keep well clear." (3) MONITOR CLOSELY: even if CPA is safe, continue to monitor. A NUC vessel may drift with current or alter if she partially regains power; (4) VHF: brief communication to confirm her situation and intentions may be appropriate; (5) CALL MASTER: at night in a crossing or overtaking situation with a NUC vessel — consider calling master. The situation could deteriorate rapidly if she is drifting; (6) ADDITIONAL LIGHT: if the NUC vessel is also making way — she shows sidelights in addition to the red lights.

B. A NUC vessel is the stand-on vessel in all situations. Your vessel must maintain course and speed and allow the NUC vessel to take avoiding action.

C. Two black balls means the vessel is at anchor. You should maintain your course but pass with caution at a safe distance as anchored vessels are not give-way.

D. The NUC vessel's situation is a temporary inconvenience. The rules of the road between power-driven vessels apply normally — the vessel on the port side gives way.

A. RAM VESSEL — IDENTIFICATION AND LIGHTS: The vessel displaying BALL-DIAMOND-BALL (day) and ALL-ROUND RED-WHITE-RED (night) is RESTRICTED IN ABILITY TO MANOEUVRE (RAM). COLREG Rule 27(b): "A vessel restricted in her ability to manoeuvre, except a vessel engaged in mineclearing operations, shall exhibit: three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white; three shapes in a vertical line where they can best be seen. The highest and lowest of these shapes shall be balls and the middle one a diamond." WHEN MAKING WAY ADDITIONALLY: masthead light(s), sidelights, and sternlight — in addition to the RAM signals. TYPICAL RAM VESSELS: a dredger; a vessel engaged in surveying or hydrographic work; a vessel engaged in buoy laying operations; a cable-laying vessel; a vessel conducting replenishment at sea (RAS); a tug engaged in a towing operation that severely restricts her ability to manoeuvre; a vessel engaged in diving operations; a minelayer. YOUR OBLIGATIONS: Rule 18(b): "A power-driven vessel underway shall keep out of the way of a vessel restricted in her ability to manoeuvre." Your vessel must keep clear. A RAM vessel with obstruction on one side: Rule 27(d) — if the vessel's ability to manoeuvre is restricted due to work on one side, she shows additional lights/shapes to indicate the safe side to pass.

B. Ball-diamond-ball is the day signal for a vessel engaged in fishing. At night, a fishing vessel shows red over white all-round lights.

C. RAM vessels have the right of way over all other vessels including sailing vessels. As a power-driven vessel, you must always give way to RAM.

D. Three vertical lights (red-white-red) are shown by a hovercraft operating in the non-displacement mode. This vessel should be treated as a power-driven vessel.