Lights & Shapes — Cheat Sheet

Rule 23 — Power-driven vessel

Any vessel propelled by machinery while underway. Length governs the masthead arrangement: ≥50 m requires two mast lights, <50 m one, and <12 m may use a single all-round white instead.

Rule 24 — Towing & pushing

A power-driven vessel towing or pushing another. The tug shows extra masthead lights depending on its length and the tow length. Tows >200 m add a diamond day-shape on both vessels.

Rule 25 — Sailing vessel

Which variant applies to you? → Motor running: use the 'engine running' variant (treated as power-driven). → Sail only, <7 m: no permanent lights needed, just keep a white light ready. → Sail only, any size: show 3 separate lights (sidelights + sternlight). If <20 m you may instead use a single tricolour lantern at the masthead — it replaces all three. Optionally (with the 3 separate lights only, never with tricolour) you may add red-over-green all-rounds at the masthead.

Rule 26 — Fishing vessel

Vessels actively fishing with gear that restricts maneuverability. Trawlers (dragging nets) show green-over-white all-round lights; other fishing vessels show red-over-white. Day shape: two cones apex-together.

Rule 27 — NUC / RAM / dredging

Three special categories: NUC (Not Under Command) — unable to maneuver due to exceptional circumstances; RAM (Restricted in Ability to Maneuver) — constrained by the nature of the work; and vessels engaged in dredging or underwater operations.

Rule 28 — Constrained by draught

A power-driven vessel severely restricted in its ability to deviate from its course due to its draught relative to the available water depth. Adds three all-round red lights vertically to the Rule 23 lights.

Rule 29 — Pilot vessel

A vessel engaged on pilotage duty — guiding ships through ports and restricted waters. Identified by white-over-red all-round lights. When at anchor or underway but off duty, it shows only the lights for its length class.

Rule 30 — Anchored / aground

Anchored vessels show one all-round white light forward (two for ≥50 m); aground vessels add two all-round red lights vertically. Day shapes: one black ball for anchored, three balls in a vertical line for aground.

Seaplanes