Masthead light
White • 225°
Right ahead to 22.5° abaft the beam either side.
21–22 — Definitions & visibility
Core recognition definitions plus the visibility-range reference that underpins the Part C lights.
Sternlight
White • 135°
After sector: 67.5° from right aft on each side.
Towing light
Yellow • 135°
Rendered as a yellow sternlight-characteristic light in towing configurations.
All-round light
360°
Unbroken over the full horizon.
23 — Power-driven vessels underway
Includes the approved Project Watch aspect geometry from Board 01 Rev D.
Power-driven vessel ≥50 m — ahead
Two masthead whites • both sidelights
Approved Project Watch direct-ahead geometry: both masthead lights exactly centred.
Power-driven vessel ≥50 m — port aspect
Wide fore/aft masthead separation • red sidelight
After masthead higher; clear side-aspect recognition geometry.
Power-driven vessel ≥50 m — starboard aspect
Wide fore/aft masthead separation • green sidelight
Mirror of the port-aspect recognition card.
Power-driven vessel <50 m — ahead
One masthead white • both sidelights
Second masthead light is optional below 50 m.
Power-driven vessel <12 m — permitted alternative
All-round white + sidelights
Permitted in lieu of the Rule 23(a) display.
<7 m, maximum speed ≤7 kn — permitted alternative
All-round white; sidelights if practicable
Specific small-vessel alternative.
Air-cushion vessel — non-displacement mode
Normal power lights + flashing yellow
Flashing yellow is additional.
WIG craft — specified near-surface operation
Normal power lights + high-intensity flashing red
Applies when taking off, landing or in flight near the surface.
24 — Towing & pushing
Towing, pushing, composite units, tows and inconspicuous partly-submerged objects.
Towing astern — tow ≤200 m — ahead
Two vertical masthead whites + sidelights
Towing vessel display from ahead.
Towing astern — tow ≤200 m — astern
Yellow towing light above white sternlight
Characteristic astern recognition pair.
Towing astern — tow >200 m — ahead
Three vertical masthead whites + sidelights
Three masthead lights indicate tow length exceeds 200 m.
DAY SHAPE
Tow >200 m — day shape
Black diamond
Towing vessel exhibits a diamond where best seen.
Rigid composite unit
Treat as a power-driven vessel
A rigidly connected pushing vessel and vessel pushed ahead are treated as one power-driven vessel.
Pushing ahead / towing alongside — not composite
Two vertical masthead whites + sidelights
No towing light above sternlight is prescribed by 24(c).
Vessel or object being towed — ahead
Sidelights
Also exhibits a sternlight; >200 m adds a diamond.
Inconspicuous partly-submerged tow
All-round white marking lights
Card is a simplified review marker; exact number depends on breadth and length.
DAY SHAPE
Partly-submerged tow — day
Diamond at aftermost extremity
Additional forward diamond if total tow length exceeds 200 m.
25 — Sailing vessels & vessels under oars
Sailing aspects, optional red-over-green, small sailing vessels, oars, and sail plus machinery.
Sailing vessel underway — ahead
Red and green sidelights
No masthead white as a sailing-vessel identifier.
Sailing vessel underway — port aspect
Red sidelight
Sternlight becomes visible only within its prescribed after sector.
Sailing vessel underway — starboard aspect
Green sidelight
Clear starboard aspect.
Sailing vessel underway — astern
White sternlight
Direct astern recognition.
Sailing vessel — optional mast lights
Red over green + normal sailing lights
Optional all-round red over green; not with the combined lantern permitted by 25(b).
DAY SHAPE
Sailing vessel also propelled by machinery — day
Cone apex down
Displayed forward where best seen.
26 — Fishing vessels
Trawling, fishing other than trawling, making way, outlying gear and Annex II additional fishing signals.
Trawler — not making way
Green over white
All-round green over all-round white.
Trawler — making way — ahead
Green over white + sidelights
Sidelights and sternlight are added when making way.
Trawler ≥50 m — making way — ahead
Masthead white abaft/higher + green over white + sidelights
Under 50 m the additional masthead light is optional.
DAY SHAPE
Trawler — day
Two cones apexes together
Fishing day shape.
Fishing other than trawling — not making way
Red over white
All-round red over all-round white.
Fishing other than trawling — making way — ahead
Red over white + sidelights
Sidelights and sternlight are added when making way.
Fishing gear extending >150 m
Additional all-round white toward gear
Direction-indicating light is placed in direction of outlying gear.
DAY SHAPE
Fishing gear extending >150 m — day
Cone apex up toward gear
Direction of gear is indicated by the cone.
Trawler shooting nets
Two white lights vertical
Additional close-proximity fishing signal.
Trawler hauling nets
White over red
Additional close-proximity fishing signal.
Trawler nets fast on obstruction
Two red lights vertical
Additional close-proximity fishing signal.
Purse seiner hampered by gear
Two yellow lights flashing alternately
Optional additional signal when hampered by fishing gear.
27 — NUC, RAM & special operations
Not under command, restricted ability to manoeuvre, dredging, diving and mine-clearance.
Not under command — not making way
Red over red
Two all-round red lights.
Not under command — making way — ahead
Red over red + sidelights
Sidelights and sternlight are added when making way.
DAY SHAPE
Not under command — day
Two black balls
Two balls in a vertical line.
Restricted ability to manoeuvre — not making way
Red-white-red
Three all-round lights vertical.
RAM — making way — ahead
Red-white-red + power-driven underway lights
Masthead light(s), sidelights and sternlight are additional when making way.
DAY SHAPE
Restricted ability to manoeuvre — day
Ball-diamond-ball
Three shapes in a vertical line.
Dredging / underwater ops with obstruction
RAM + red obstruction side + green safe side
Two red all-round lights mark obstruction; two green mark side another vessel may pass.
DAY SHAPE
Dredging / underwater ops — day
Ball-diamond-ball + balls obstruction + diamonds safe
Maximum practical horizontal separation is required by Annex I.
Small diving-operation vessel
Red-white-red
When full dredging display is impracticable, also carries rigid Code flag A.
DAY SHAPE
Diving operation — Code flag A
Rigid replica • all-round visibility
Not less than 1 m high under Rule 27(e)(ii).
ADDITIONAL MINE-CLEARANCE SIGNALS
Mine-clearance vessel — additional night signals
Three all-round green lights
One near the foremast head and one at each end of the fore yard. These are additional to the lights otherwise prescribed for a power-driven vessel.
DAY SHAPE
Mine-clearance vessel — day
Three black balls in prescribed arrangement
Indicates danger to vessels approaching within 1000 m.
28 — Constrained by draught
Optional additional signal for a power-driven vessel constrained by her draught.
Constrained by draught — underway — ahead
Three all-round red + Rule 23 lights
The three red all-round lights are optional additional signals.
DAY SHAPE
Constrained by draught — day
Black cylinder
Optional additional day shape.
29 — Pilot vessels
Pilotage duty underway and at anchor.
Pilot vessel on pilotage duty — underway — ahead
White over red + sidelights
Sternlight is also exhibited.
Pilot vessel on pilotage duty — at anchor
White over red + anchor light(s)
Anchor light(s) or shape are additional.
30 — Anchored & aground
Anchor displays by length and aground additions.
Vessel <50 m at anchor
One all-round white
May exhibit one all-round white where best seen.
Vessel ≥50 m at anchor
Forward white higher + after white lower
Forward anchor light is higher than after light.
DAY SHAPE
Vessel at anchor — day
One black ball
Displayed where best seen.
Vessel aground
Anchor light(s) + two all-round red
Aground adds two vertical red all-round lights.
DAY SHAPE
Vessel aground — day
Three black balls
Three balls in a vertical line.
31 — Seaplanes & WIG craft
Closest-possible compliance where prescribed characteristics or positions are impracticable.
Seaplane / WIG craft where normal positioning impracticable
As closely similar as possible
Rule 31 is a closest-possible-compliance provision rather than a unique recognition pattern.
Annex I — Master day-shape primitives
Project Watch renders these black on a light field for maximum recognition.
DAY SHAPE
Ball
Black ball
Master primitive.
DAY SHAPE
Cone — apex up
Black cone
Master primitive.
DAY SHAPE
Cone — apex down
Black cone
Master primitive.
DAY SHAPE
Diamond
Black diamond
Two cones with common base.
DAY SHAPE
Cylinder
Black cylinder
Height twice its diameter in the full-size Annex I specification.