Navigation & Bridge
COLREG Navigation Lights, Shapes & Sound Signals Checklist
Updated · Written by SeaReady in our own words. Not affiliated with OCIMF, RightShip, CDI, any MoU or any administration — always check the current official documents.
2. Not under command, restricted, constrained by draught, anchored and aground
These are the signals inspectors most often ask the officer of the watch to show and explain.
| Situation | Lights and shapes | What to check on board |
|---|---|---|
| Not under command (COLREG Rule 27(a)) | Two all-round red lights in a vertical line; by day two balls. Sidelights and sternlight only when making way through the water. | Test both red lanterns. Make sure the OOW knows to switch the sidelights and sternlight off when the ship is stopped and making no way. |
| Restricted in ability to manoeuvre (COLREG Rule 27(b)) | Three all-round lights in a vertical line: red, white, red; by day ball, diamond, ball. Masthead lights, sidelights and sternlight in addition when making way. | Test the red-white-red group and check the diamond shape is on board with the balls. |
| Constrained by draught (COLREG Rule 28) | May exhibit three all-round red lights in a vertical line, or a cylinder, in addition to the normal power-driven vessel lights. | If the ship trades where it may be constrained by draught, test the three red lanterns and check the cylinder is on board. |
| At anchor and aground (COLREG Rule 30) | At anchor: an all-round white light or one ball in the fore part (plus a lower all-round white light at or near the stern). Aground: in addition, two all-round red lights in a vertical line and by day three balls. | Check anchor lights on both supplies and that three balls are available for the aground signal. |
3. Duplicate lights, spare lamps and LED lifespan
Duplication rules are often quoted wrongly. The merchant-ship rule is in MSC.253(83); the 500 GT and three-minute rules belong to large-yacht codes.
| Ship type and source | Rule | What to check on board |
|---|---|---|
| Merchant ships (MSC.253(83), para 4.1.3) | On ships of 50 m or more, the masthead light, sidelights and sternlight should be duplicated or fitted with duplicate lamps. Para 4.1.5 asks for enough spare lamps, allowing for that duplication. MSC.253(83) is the performance standard IMO recommends for lights and controllers installed on or after 1 January 2009. | Check which arrangement the ship has (duplicate lanterns or twin lamps), that the standby circuit works, and that spare lamps of the type the maker specifies are on board. |
| LED lights (MSC.253(83), para 4.3) | LED output fades slowly while power use stays the same, so either an alarm tells the OOW when intensity drops below the COLREG level, or the LEDs are used only within the lifespan the maker states. | Find out which option the ship uses. If it is the lifespan, record the installation date and the maker’s lifespan in the planned maintenance system and renew before it ends. |
| Large yachts (UK REG Yacht Code §17.1, MI-103 §18.1) | UK REG Yacht Code: on yachts of 50 m and over the main lights are duplicated or have duplicate lamps; spare bulbs that can be fitted within three minutes may be accepted, but from 500 GT, and for LED lights on any size, they must be duplicate lights. Marshall Islands MI-103: under 500 GT, a spare lamp that the crew can fit within three minutes at sea can replace duplicate lights. | Check the arrangement against the yacht’s own code and flag, and time a lamp change if the yacht relies on spare lamps. |
4. Day shapes and sound signals (COLREG Rules 27–35 and Annex I)
Shapes and sound signalling equipment must be ready before the ship sails. Missing, non-compliant or seriously deteriorated lights, shapes or sound signals are listed as a ground for detention in Appendix 2 of IMO Resolution A.1206(34); see what can detain a ship.
| Item and rule | What is required | What to check on board |
|---|---|---|
| Shapes (COLREG Annex I, section 6) | Black. Ball at least 0.6 m diameter; cone 0.6 m base and as high as its diameter; diamond two such cones base to base; cylinder at least 0.6 m diameter and twice as high. Shapes at least 1.5 m apart vertically. | Unstow and inspect every shape: frames, toggles and halyards free of seizure and rot, and the crew able to hoist the NUC or anchor signal quickly. |
| Sound signalling equipment (COLREG Rule 33) | Whistle on vessels of 12 m or more; bell in addition on vessels of 20 m or more; gong in addition on vessels of 100 m or more. | Sound the whistle from each control position, check the bell and striker on the forecastle, and on ships of 100 m or more check the gong and striker aft. |
| Restricted visibility (COLREG Rule 35) | Power-driven vessel making way: one prolonged blast at intervals of not more than 2 minutes. Under way but stopped and making no way: two prolonged blasts about 2 seconds apart, at intervals of not more than 2 minutes. NUC, RAM, CBD, sailing, fishing, towing or pushing: one prolonged followed by two short blasts at intervals of not more than 2 minutes. | If an automatic fog-signal timer is fitted, check it sounds the right signal for each case and that the OOW can switch between them at once. |
| At anchor in restricted visibility (COLREG Rule 35(g)) | Bell rung rapidly for about 5 seconds at intervals of not more than 1 minute; on vessels of 100 m or more the bell is rung forward and then the gong rapidly for about 5 seconds aft. | Make sure the anchor watch knows who rings the bell and the gong, and that both can be reached. |
5. Daylight signalling lamp, pilot card and pre-departure routine
- Daylight signalling lamp (SOLAS V/19): it must work from a power source not solely dependent on the ship’s supply. Test it on its own battery, check the charger and keep spare lamps with it.
- Pilot card, wheelhouse poster and manoeuvring booklet (IMO Res. A.601(15)): the pilot card is filled in with current draughts and propulsion and steering status for each pilotage; ships of 100 m and over, and all chemical tankers and gas carriers, also have the wheelhouse poster displayed and the manoeuvring booklet on the bridge.
- Before departure: test every navigation light on main and standby circuits and on the emergency supply, prove the controller alarms, sound the whistle, and record the test in the deck logbook.
- Keep the shapes where the watch can reach them, with three balls, a diamond and, where relevant, a cylinder.
- Record LED installation dates and the maker’s lifespan in the planned maintenance system if the ship relies on lifespan rather than an intensity alarm.
Questions seafarers ask
Can faulty navigation lights or a missing day shape get a ship detained?
Yes. Appendix 2 of IMO Resolution A.1206(34), the PSC procedures, lists "absence, non-compliance or serious deterioration of lights, shapes or sound signals" among the SOLAS areas where a serious failure is a ground for detention. The same procedures also list officers not knowing how to test their navigation equipment, navigation lights included, among the operational findings for which detention may be considered.
What does MSC.253(83) say about LED navigation lights?
IMO Resolution MSC.253(83), the performance standard for navigation lights and controllers installed on or after 1 January 2009, notes that LED output fades over time. It gives two options: an alarm that tells the officer of the watch when intensity falls below the COLREG level, or using the LEDs only within the lifespan the maker states. Ships using the second option should keep the installation date and lifespan in their maintenance records.
When should navigation lights be duplicated?
Under MSC.253(83) para 4.1.3, ships of 50 m or more should have the masthead light, sidelights and sternlight duplicated or fitted with duplicate lamps. The 500 GT and three-minute spare-lamp rules come from large-yacht codes such as the UK REG Yacht Code and Marshall Islands MI-103, not from COLREG or MSC.253(83). Always check the ship’s flag and class rules too.
Does a ship not under command show sidelights?
Only when it is making way through the water. Under COLREG Rule 27(a) a vessel not under command shows two all-round red lights in a vertical line (two balls by day). When making way it adds sidelights and a sternlight; when stopped and making no way it shows the red lights only.
How should the daylight signalling lamp be checked before an inspection?
SOLAS V/19 requires the daylight signalling lamp to work from a power source that does not depend only on the ship’s supply. Switch it on from its own battery, not ship’s mains, check the battery is charged and the charger works, and make sure spare lamps are kept with it. Flat batteries and missing spare lamps are the usual findings.
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