A Brief Understanding of COLREG 1972 (International Regulations for Preventing Collisions at Sea)
This article provides a brief analysis of specific rules and technical specifications from the International Regulations for Preventing Collisions at Sea (COLREG). It covers a range of topics including the definitions, positioning, and technical details of marine navigational lights and shapes as outlined in the COLREG 1972. The discussion spans from the fundamental definitions in Rule 21 to the intricate requirements of light intensity and sectors in Annex I.
Each section meticulously examines the stipulations for different vessel types, ensuring comprehensive coverage of the regulations. The aim is to distill these complex regulations into a clear, accessible format, enhancing understanding and compliance among maritime professionals and enthusiasts.
Rule 21 — Definitions:
Masthead light: A white light placed over the centerline, visible over a 225-degree arc from ahead to 22.5 degrees abaft the beam on either side.
Sidelights: A green light on the starboard side and a red light on the port side, each showing an unbroken light over a 112.5-degree arc from right ahead to 22.5 degrees abaft the beam. For vessels under 20 meters, these can be combined into one lantern.
Sternlight: A white light at the stern, showing an unbroken light over a 135-degree arc from right aft on each side of the vessel.
Towing light: A yellow light with the same characteristics as the sternlight.
All-round light: A light showing unbroken over 360 degrees.
Flashing light: A light flashing at regular intervals at a frequency of 120 flashes or more per minute.
Rule 24 — Towing and Pushing:
Covers lighting for towing and pushing vessels. Towing vessels must exhibit two masthead lights in a vertical line (three if the tow exceeds 200 meters), sidelights, a sternlight, and a towing light. When vessels are pushed in a group or alongside, they must be lighted as one vessel with specific lights at different positions.
Rule 25 — Sailing Vessels Underway and Vessels Under Oars:
Sailing vessels must exhibit sidelights and a sternlight. Vessels less than 20 meters in length may combine these lights into one lantern.
Sailing vessels may also show two all-round lights (red over green) at the masthead.
Vessels under oars should exhibit a white light or have a torch or lantern ready to prevent collision.
Rule 26 — Fishing Vessels:
Fishing vessels must exhibit lights and shapes specific to their fishing methods (trawling or other than trawling).
They must show all-round lights in specific colors and arrangements and additional lights or shapes if they have outlying gear extending more than 150 meters horizontally from the vessel.
Rule 27 — Vessels Not Under Command or Restricted in Their Ability to Manoeuvre:
These vessels must exhibit two all-round red lights, two balls or similar shapes, and, if making way through the water, sidelights and a sternlight.
Different lights and shapes are required for vessels engaged in dredging, underwater operations, or mine clearance operations.
Rule 28 — Vessels Constrained by Their Draught:
A vessel constrained by her draught must exhibit three all-round red lights in a vertical line or a cylinder in addition to the lights prescribed for power-driven vessels.
Rule 29 — Pilot Vessels:
When engaged in pilotage duty, these vessels must exhibit two all-round lights in a vertical line (white over red), sidelights, and a sternlight. When at anchor, they must also show the lights or shape prescribed in Rule
Rule 30 — Anchored Vessels and Vessels Aground:
Specifies the lighting and shape requirements for vessels at anchor or aground. The rule ensures that such vessels are visible and that their status as being at anchor or aground is clearly communicated to prevent collisions.
Rule 31 — Seaplanes:
This rule includes lighting requirements for seaplanes on the water. It ensures that seaplanes are visible and can be identified by other waterborne traffic.
Rule 32 — Definitions:
Provides definitions for the terms used in the rules concerning sound signaling appliances. It is essential for understanding and complying with the requirements for sound signals under various conditions.
Rule 33 — Equipment for Sound Signals:
Outlines the required equipment for sound signals on vessels. This includes specifications for whistles, bells, and gongs, ensuring vessels can communicate effectively in conditions where visibility is restricted, such as fog.
Also, Annex I of the COLREG document, covering the positioning and technical details of lights and shapes:
1.Definition:
The term “height above the hull” is defined as the height above the vessel’s uppermost continuous deck, measured vertically from the position directly beneath the location of the light.
2. Vertical Positioning and Spacing of Lights:
The regulation specifies the height at which various lights (such as masthead lights) should be placed on vessels of different lengths. For example, on power-driven vessels 20 meters or longer, the forward masthead light should be at least 6 meters above the hull. When two masthead lights are carried, the aft one must be at least 4.5 meters higher than the forward one.
3. Horizontal Positioning and Spacing of Lights:
This section addresses the horizontal placement of lights on vessels. For power-driven vessels, the horizontal distance between two masthead lights must not be less than half the vessel’s length but not more than 100 meters. Sidelights should not be placed in front of forward masthead lights and should be near the sides of the vessel.
4. Location of Direction-Indicating Lights for Fishing Vessels, Dredgers, and Underwater Operation Vessels:
Lights indicating the direction of outlying gear from fishing vessels must be placed horizontally at a distance of 2 to 6 meters from the all-round red and white lights. These lights should not be higher than the all-round white light or lower than the sidelights.
5. Screens for Sidelights:
Vessels of 20 meters or more in length must have inboard screens painted matt black for their sidelights. For vessels less than 20 meters, if necessary to meet the requirements, inboard matt black screens should also be fitted.
6. Shapes:
Shapes used for signaling, such as balls, cones, cylinders, and diamond shapes, must be black and of specific dimensions. For example, a ball must have a diameter of not less than 0.6 meters. The vertical distance between shapes should be at least 1.5 meters, and on smaller vessels (less than 20 meters), smaller shapes may be used.
7. Colour Specification of Lights:
The chromaticity of all navigation lights must conform to standards set by the International Commission on Illumination (CIE), ensuring that the colors of these lights are consistent and recognizable.
8. Intensity of Lights:
The minimum luminous intensity of lights is to be calculated using a specific formula, taking into account factors like atmospheric transmissivity and the range of visibility of the light in nautical miles. For standard lights, a visibility of approximately 13 nautical miles is assumed.
9. Horizontal Sectors:
This section details how the intensity of lights like sidelights, sternlights, and masthead lights should be maintained and diminished across different horizontal angles. All-round lights should be located to avoid being obscured by any part of the vessel, ensuring visibility from all angles.
10. Vertical Sectors:
For electric lights (except on sailing vessels underway), the vertical sectors must ensure that at least the required minimum intensity is maintained from 5 degrees above to 5 degrees below the horizontal. Additionally, at least 60% of the required minimum intensity must be maintained from 7.5 degrees above to 7.5 degrees below the horizontal.
For sailing vessels underway, the vertical sectors of electric lights must maintain at least the required minimum intensity from 5 degrees above to 5 degrees below the horizontal. Furthermore, at least 50% of the required minimum intensity should be maintained from 25 degrees above to 25 degrees below the horizontal.
For lights other than electric, these specifications should be met as closely as possible.
11. Intensity of Non-Electric Lights:
Non-electric lights should comply, as far as practicable, with the minimum intensities specified in the table given in section 8 of Annex I. This implies that while electric lights have precise requirements, non-electric lights are expected to adhere to these standards to the best of their ability, given the technological limitations.
12. Maneuvering Light:
The maneuvering light, as described in Rule 34(b), should be placed in the same fore and aft vertical plane as the masthead light(s). Ideally, it should be at a minimum height of 2 meters vertically above the forward masthead light but not less than 2 meters vertically above or below the after masthead light.
On vessels with only one masthead light, the maneuvering light, if fitted, should be placed where it can best be seen and at least 2 meters vertically apart from the masthead light. This ensures clear visibility and distinction of the maneuvering light from other navigation lights
The examination of the COLREG rules and Annex I reveals a detailed and methodical approach to maritime safety and navigation. These regulations, encompassing various aspects of light and shape specifications, are critical in maintaining safe navigation and preventing collisions at sea. From the positioning of lights on different vessels to the intensity and color specifications, each rule plays a vital role in ensuring visibility and clarity in communication among vessels. This article’s exploration underscores the importance of adhering to these regulations and highlights the intricate balance between technical requirements and practical navigational needs. Ultimately, the insights gained from this analysis reinforce the significance of COLREGs as an essential framework for maritime safety and efficient navigation.
Eray Ceylan
Naval Architect and Marine Engineer