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Vessel not under command (NUC)

Two red all-round lights in a vertical line. Two reds in a vertical line: "I am not under command." No masthead lights.

fog
60°

Drag across the scene to walk around the ship. Tap a light to see its name.

arcs = Rule 21 sectors

One prolonged and two short blasts at intervals of not more than 2 minutes (Rule 35c).

Lights (Rule 27a)

LightColourSectorHeight above water
red all-round light (upper) red all-round, 360° 17 m
red all-round light (lower) red all-round, 360° 15 m
green sidelight (when making way) green sidelight, starboard, 112.5° 13 m
red sidelight (when making way) red sidelight, port, 112.5° 13 m
white sternlight (when making way) white stern, 135° (around the stern) 6 m

Model: a 90 m ship with the superstructure aft. Heights and positions follow COLREG Annex I (positioning of lights).

Day shapes

Shapes are black and hoisted where they can best be seen: a ball at least 0.6 m in diameter, vertical spacing at least 1.5 m (Annex I, section 6). Set the trainer above to day to see them.

Fog signal

One prolonged and two short blasts at intervals of not more than 2 minutes (Rule 35c).

A short blast lasts about 1 second, a prolonged blast 4 to 6 seconds (Rule 32). The play button is in the trainer above.

What to watch for

A NUC carries no masthead lights. Sidelights and sternlight only while she is still making way.

By day: two balls in a vertical line.

Quick answers

What lights does a vessel not under command (NUC) show at night?

Two red all-round lights in a vertical line. In full: red all-round light (upper); red all-round light (lower); green sidelight (when making way); red sidelight (when making way); white sternlight (when making way).

What day shapes does a vessel not under command (NUC) show?

By day she shows: upper ball; lower ball.

What is the fog signal of a vessel not under command (NUC)?

One prolonged and two short blasts at intervals of not more than 2 minutes (Rule 35c).

Test yourself: lights quiz All 13 vessel types Open in the trainer