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27

Vessels Not Under Command or Restricted in Ability to Manoeuvre

NUC shows two red all-round lights vertically. RAM shows red-white-red all-round lights vertically.

Rule 27 prescribes lights for NUC and RAM vessels.

a
A vessel not under command shall exhibit: two all-round red lights in a vertical line where they can best be seen; sidelights and sternlight when making way.
b
A vessel restricted in her ability to manoeuvre shall exhibit: three all-round lights in a vertical line — the highest and lowest being red and the middle one being white (red-white-red); masthead lights, sidelights and sternlight when making way.

Day shapes: NUC shows two balls in a vertical line. RAM shows ball-diamond-ball in a vertical line.

d
A vessel engaged in dredging or underwater operations when restricted in ability to manoeuvre shall additionally show two red all-round lights or two balls on the obstructed side, and two green all-round lights or two diamonds on the side available for passing.

Recognition Sequence

1

Classify the vessel state first: underway, making way, stopped, at anchor, aground, towing, fishing, pilotage or special condition.

2

Read special lights vertically from top to bottom before using sidelights and sternlight to confirm aspect.

3

Then confirm the answer with the day shape, vessel length and any extra signal such as towing lights, deck illumination or a cylinder.

Exam Focus

1

Avoid identifying a vessel from one colour alone. Many mistakes come from spotting a red light and guessing before checking the full pattern.

2

If the question mentions 'making way', 'underway but stopped', 'at anchor' or 'aground', that wording usually determines which extra lights or shapes appear.

Key Takeaways

1

NUC: two red all-round lights vertically (day: two balls)

2

RAM: red-white-red all-round lights (day: ball-diamond-ball)

3

Dredging vessels show red on obstructed side, green on clear side

4

Sidelights/sternlight only when making way

Common Mistakes

Confusing NUC lights (red-red) with RAM lights (red-white-red)

Forgetting that NUC and RAM only show sidelights when making way

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