Navigation Light Controller (NLC)-A quick guide the requirements

Navsregs>COLREGS>NLC

Bridge of general cargo ship

Some more information from Resolution MSC.253(83)

This post is a continuation from of the last post covering navigation lights performance standards.

Click here to view a cop of MSC 258>

What is a Navigation Light Controller?

Navigation Light Controller (NLC) is a device enabling operational control of a Navigation Light.

What are the requirements of a Navigation Light Controller?Bridge window with gold sun screens

  • An NLC should facilitate ON/OFF controls of individual NLs
  • An NLC should provide visual indications of ON/OFF status of NLs
  • An NLC on board a ship not less than 50 m in length should present the status of all NLs in a logical presentation, meeting the requirements set out in resolution MSC.191(79), e.g., by symbol marks on a display. Click here to view the resolution
  • All indicators of an NLC should be dimmable to ensure easy reading without disturbing the night vision of the Officer of the Watch. The brightness of a display, if fitted, of an NLC should be controllable.

Note: Pre-programmed NL group settings may be provided

What are the requirements regarding light failures?

An NLC on board a ship not less than 50 m in length should provide the alarm for:

  • A failure of power supply to the Navigation Lights
  • A failure, including short circuit, of a lamp which is switched ON.

An NLC should support the use of standardized serial interfaces for marine navigation and communication systems

The NLC should have a bi-directional interface to transfer alarms to external systems and receive acknowledgements of alarms from external systems. The interface should comply with the relevant international standards

Power supply and fallback arrangements

Each navigation light should be connected, via separate circuits, to a navigation light controller located on the bridge in order to avoid any navigation light failure, including short circuit, that affect any navigation lights connected to the controller.

Navigation lights and controllers, and associated equipment should be so constructed and installed, as necessary, that they are readily accessible for inspection and maintenance purposes.


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​Navigation Light Performance Standards-A handy guide to the IMO Resolution

Navsregs>COLREGS>Navigation light performance standards summary

Sunrise over a jettyResolution MSC.253(83) Performance Standards for Navigation lights, Navigation Light Controller and Associated Equipment

The last post contained a contents list of this Resolution, this post goes into a bit more detail with a summary of some of its contents.

Click here to view a cop of MSC 258>

What are the  navigation lights?

  • Masthead light
  • Sidelights
  • Sternlight
  • Towing light
  • All-round light
  • Flashing light
  • All-round flashing yellow light required for air-cushion vessels
  • Manoeuvering light

Note: Unless expressly required, these Navigation lights  should appear steady and non-flashing.

The document also refers to international standard  IEC 60945.

What material should navigation lights be produced in?Tug Masthead lights

Material that is:

  • Robust
  • Non-corroding material,
  • Should ensure a long-term durability for the optical qualities 

What is the requirement to carry spare Navigation lights and lamps?

  • A masthead light, sidelights and a sternlight installed on board a ship not less than 50m in length should be duplicated or be fitted with duplicate lamps
  • A sufficient number of spare lamps for Navigation lights should be carried onboard


Note
: Only lamps specified by the manufacturer should be used.

By how much may the  Luminous intensity vary?

Within the prescribed sector in which the minimum luminous intensity is required the vertical intensity distribution of the light should be  uniform in such a way that the measured minimum and maximum luminous intensity values  do not differ by more than a factor of 1.5.

This is to avoid  intensity changes which may result in the appearance of a flashing light.

What special requirements are there for Navigation lights using LEDs?

  • An alarm  must notify the Officer of the Watch that the luminous intensity of the light reduces below the level required by COLREGs
  • The lifespan of LEDs should be determined and clearly notified by the manufacturer

What markings must a navigation light have?Navigation lights on a tug's mast

Each light should be marked with:

  • The type/category of the light
  • The serial and certificate number
  • Head line directions
  • Range in nautical miles
  • Nominal wattage of the light source in watts, if different values lead to different ranges. 

How should Navigation lights be installed?

Navigation lights should be installed in such a way so as:

  • To protect navigation watch keeping
  • To ensure that the light shows over the  required arcs of visibility
  • To satisfy the required vertical separation and location requirements in all normal operating trim conditions
  • So that the lamp specified by the manufacturer can be efficiently  and readily replaced, without elaborate re-calibration or readjustment
  • So that they are readily accessible for inspection and maintenance purposes

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Performance Standards for Navigation lights- A summary

Navsregs>COLREGS>Navigation light performance standards
LightandBlockAnd now,  the dive down into navigation light regulations now hits the bottom of detail with an IMO resolution. 

The post in Navigation light series gives a quick summary into the performance standards required of vessel’s navigation lights.

What document gives the performance Standards for Navigation lights?

​Resolution MSC.253(83)

Performance Standards for Navigation lights, Navigation Light Controller and Associated Equipment

Click here for the document>

Navigation Light equipment should be designed, tested, installed and maintained based on these standards.

What is the purpose of Navigation Lights?

  • Identify ships
  • Notify their intentions at sea 

What is the purpose of a Navigation Lights Controller?

is to provide means of:

  • Control of Navigation lights
  • Monitoring of the status of Navigation lights 

Stern light of a ferry

What is covered in MSC 253?

1 Scope

2 Application

3 Definitions

  • Associated equipmentLightCloseMast
  • COLREGs
  • Lamp
  • Length
  • Navigation Light (NL)
  • Navigation Light Controller (NLC)
  • SOLAS

4 Navigation Lights

  • General
  • Luminous intensity distribution
  • Special requirements for lights using LEDs

5 Navigation Light Controller

  • On off switches
  • Status indications
  • Pre-programming
  • Alarms
  • Dimming
  • Interfaces

6 Power supply and fallback arrangementsMast and flags of a bunker barhe

  • Need for separate circuits
  • Ability to operate  by an emergency source
  • Automatic switch over to the alternative source of power is permitted.

7 Associated equipment

  • General requirements for  associated equipment
  • Screens for sidelight may be a part of a ship’s structure.

8 Marking

The markings that each Navigation Light should have.

9 Installation of navigation lights and associated equipment.

The general requirements required of navigation lights

10 Maintenance

  • The requirements for the ease of replacing the lights
  • The requirements for the ability to maintain the lights

The next post will look at some of these performance standards in more detail.


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Where should a vessel’s sidelights be carried?

Sidelights have simpler rules on their placement than masthead lights, and therefore this post is shorter than the last.

Sidelights on MV Balmoral

Vertical

  • ​ The sidelights of a power-driven vessel shall be placed at a height above the hull not greater than three quarters of that of the forward masthead light.
  •  They shall not be so low as to be interfered with by deck lights

The sidelights, if in a combined lantern and carried on a power-driven vessel of less than 20 meters in length, shall be placed not less than 1 meter below the masthead light.Port Sidelight

Horizontal

On a power-driven vessel of 20 meters or more in length:

  • The sidelights shall not be placed in front of the forward masthead lights.
  • They shall be placed at or near the side of the vessel

Sidelight position summary

SideLightspositionSmall


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Where should a vessel’s masthead lights be placed?

Power Driven vessel end on

Navsregs>COLREGS>Masthead light position

More delving into the detail of navigation lights, this time its the positioning of masthead lights.

The vertical positioning of Masthead lights

What part of the COLREGs covers the vertical positioning of Masthead lights?

Annex 1 part 2.

At what height should masthead lights be carried?

On a power-driven vessel of 20 meters or more in length:

The forward masthead light, or if only one masthead light is carried, then that light is:

  • At a height above the hull of not less than 6 meters

and

  •  If the breadth of the vessel exceeds 6 meters, then at a height above the hull not less than such breadth, so however that the light need not be placed at a greater height above the hull than 12 meters

The masthead light of a power-driven vessel of 12 meters but less than 20 meters in length:

  •  Shall be placed at a height above the gunwale of not less than 2.5 meters.

The masthead light of a power-driven vessel of less than 12 meters in length:

  • These may carry the uppermost light at a height of less than 2.5 meters above the gunwale.
  • When however a masthead light is carried in addition to side-lights and a sternlight or the all-round light prescribed in Rule 23(c)(i) is carried in addition to sidelights, then such masthead light or all-round light shall be carried at least 1 meter higher than the

The masthead light or lights prescribed in shall be so placed as to be above and clear of all other lights and obstructions except for Not Under Command Lights and Restricted in Manoeuvrability.

MastClutter

What is the separation of two masthead lights?

The after one shall be at least 4.5 meters vertically higher than the forward one.

The vertical separation of masthead lights of power-driven vessels shall be such that in all normal conditions of trim the after light will be seen over and separate from the forward light at a distance of 1000 meters from the stem when viewed from sea level.

Horizontal positioning of Masthead lights

What part of the COREGS covers the horizontal positioning of Navigation lights?

Annex 1 3 Horizontal positioning and spacing of lights

the horizontal distance between them shall not be less than one half of the length of the vessel but need not be more than 100 meters. The forward light shall be placed not more than one quarter of the length of the vessel from the stem.

A quick summary of the Masthead Light distances

LightsMastheadpositionSmall


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The range of ship’s navigation lights

Navsregs>COLREGS>Navigation Light Range

​This post starts of with the simple facts of COLREG 22 and then delves deeper and deeper into definitions; deep into the world of lux, lumens and candelas.

Sunset in the Med

The range of Navigation lights

What Rule states the visibility of Navigation lights?

Rule 22-visibility of lights

Note: This Rule states that navigation lights shall have an intensity as specified in Section 8 of Annex I to the COLREGS.

What is the range of Navigation lights in a vessel of 50 meters or more in length?

  • Masthead light- 6 miles
  • Sidelight-3 miles
  • Sternlight-3 miles
  • Towing light-3 miles
  • A white, red, green or yellow all-round light-3 miles

What is the range of Navigation lights in a vessel of 12 meters or more in length but less than 50 meters in length?

  • Masthead light, 5 miles; except that where the length of the vessel is less than 20 meters, 3 miles
  • Sidelight- 2 miles
  • Sternlight-2 miles;
  • Towing light-2 miles;
  •  White, red, green or yellow all-round light-2 miles

What is the range of Navigation lights in a vessel of less than 12 meters in length?

  • Masthead light- 2 miles
  • Sidelight- 1 mile
  • A sternlight- 2 miles
  • Towing light-2 miles
  • White, red, green or yellow all-round light- 2 miles

What is the range of Navigation lights of an inconspicuous, partly submerged vessel or object being towed?

White all-round light- 3 miles.

Waiting for the amplitude

The intensity of Navigation lights

The intensity required to achieve the minimum range is derived from a formula given in Section 8 of Annex I to the Colregs.

The intensity formula

1=3.43 × 1 06×T × D2 × K-D

What do the parts of the Navigation light intensity formula mean?

I is luminous intensity in candelas under service conditions

The candela is the SI unit of luminous intensity.  It is the luminous power per unit solid angle emitted by a point light source in a particular direction.

Or to be more accurate, it  is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×1012 hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

The steradian is a square radian, and is the SI unit of solid angle.

T is threshold factor 2 × 10-7 lux

The lux is the SI unit of illuminance and luminous emittance, measuring luminous flux per unit area.It is equal to one lumen per square metre. It is used as a measure of the intensity, as perceived by the human eye.

The lumen is  the SI unit of luminous flux, a measure of the total quantity of visible light emitted by a source.

D is range of visibility (luminous range) of the light in nautical miles

The luminous range is the maximum distance at which a light can be seen, as determined by the luminous intensity of the light, the atmospheric transmission factor and the threshold of illuminance on the eye of the observer.

Ship's at anchor off Gibraltar

 K is atmospheric transmissivity.

Atmospheric transmissivity is he ratio of the directly transmitted flux incident on a surface after passing through unit thickness of the atmosphere to the flux that would be incident on the same surface if the flux had passed through a vacuum.

The value of K shall be 0.8, corresponding to a meteorological visibility of approximately 13 nautical miles.


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When to show Navigation lights

Navsregs>COLREGS>When to show Navigation lights
Ferry mast

Turn on the Navigation Lights

Bit of backtracking in this post, back to the fundamental question of when to turn the navigation lights on. 

What COLREG  Rule states when navigation lights should be shown?

Rule 20

​When must Navigation lights be shown?

  • Sunset to Sunrise-During the day
  • Sunrise to Sunset-During the night
  • In restricted visibility
  • May be exhibited in all other circumstances when it is deemed necessary.

What other lights can be shown from sunset to sunrise?

No other lights shall be exhibited, except such lights as:

  • Cannot be mistaken for the lights specified in the COLREGS
  • Do not impair their visibility or distinctive characterer
  • Do not Interfere with the keeping of a proper look-out

What is Restricted Visibility?

This is  any condition in which visibility is restricted by:

  • Fog
  • Mist
  • Falling snow
  • Heavy rainstorms
  • Sandstorms
  • Any other similar causes.

See COLREG Rule 3


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Navigation lights- The horizontal cut-offs

Navsregs>COLREGS>Horizontal cut-offs

A quick guide to some of the details in COLREG Annex 1

Sidelights on MV Balmoral

Following the theme of Navigation Light horizontal arcs this post now descended into the details of Annex 1.

Colreg Annex 1

What part of the Rules defines the horizontal cut-offs of Navigation Light?

Annex 1 section 9

What is the horizontal cut off for sidelights in the forward direction?

In the forward direction they should show the minimum required intensities.

The intensities shall decrease to reach practical cut-off between 1 degree and 3 degrees outside the prescribed sectors.

What is the cut-off requirements for the other sectors?

For sternlights and masthead lights and at 22.5 degrees abaft the beam for Masthead lights MV Balmoralsidelights, the minimum required intensities shall be maintained over the arc of the horizon up to 5 degrees  of the prescribed limits. 

From 5 degrees within the sectors the intensity may decrease by 50 percent up to the prescribed limits; it shall decrease steadily to reach practical cut-off at not more than 5 degrees outside the prescribed sectors.

How much can an all-round light be obscured?

Not more than 6 degrees, except anchor lights which need not be placed at an impracticable height above the hull.NUC lights

If it is impracticable to comply with these requirements by exhibiting only one all-round light, two all-round lights shall be used suitably positioned or screened so that they appear, as far as practicable, as one light at a distance of one mile.

Sidelight screens

The sidelights of vessels of 20 metres or more in length shall be fitted with inboard screens painted matt black, and meeting the horizontal sector  requirements of  Annex 1.

On vessels of less than 20 metres in length the sidelights, if necessary to meet the horizontal sector  requirements of the  Annex, shall be fitted with inboard matt black screens.

With a combined lantern with a very narrow division between the green and red sections, external screens need not be fitted.

There is another level of detail below COLREG Annex 1, and that is contained within an IMO Resolution.

IMO RESOLUTION MSC.253(83)

Perfomance standards for Navigation lights

Within MSC 253 there are paragraphs giving more details on cut offs and intensity.

Cut-off

In the horizontal directions where decrease of luminous intensity to ìpractical cut-offî is required by section 9 of Annex I to COLREGs, the luminous intensity should be no more than 10% of the average luminous intensity within the prescribed sector for vessels not less than 12 m in length.

Uniformity of intensity

Within the prescribed sector in which the minimum luminous intensity is required  the horizontal intensity distribution of the light should be uniform so that the measured minimum and maximum luminous intensity values do not differ by more than a factor of 1.5 for vessels not less than 12 m in length.

This is to avoid luminous intensity changes which may result in the appearance of a flashing light

Click here for IMO MSC 253>


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Navigation lights defined

Navsregs>COLREGS>Navigation Lights defined

Down another level, down past the Rule list, down through the power-driven vessel rule, down to some definitions.

A quick guide to Navigation light definitions

Where are the definitions for Navigation lights?

Section C  of the COLREGS, Rule 21.

Here are those definitions condensed down to some easy to remember facts.

What is a masthead light?A Masthead Light

  •  White light
  •  Placed over the fore and aft centerline of the vessel showing an unbroken light over an arc of the horizon of 225 degrees
  • So fixed as to show the light from right ahead to 22.5 degrees abaft the beam on either side of the vessel

What are Sidelights?

  • Green light on the starboard side and a red light on the port side Port Sidelight
  • Each showing an unbroken light over an arc of the horizon of 112.5 degrees
  • So fixed as to show the light from right ahead to 22.5 degrees abaft the beam on its respective side.

In a vessel of less than 20 meters in length the sidelights may be combined in one lantern carried on the fore and aft center-line of the vessel.

When did the Red and Green sidelights come into use?

In 1848 the UK issued  regulations requiring steam vessels to display red and green sidelights as well as a white masthead light. This was a follow on from an act of 1846 that became the basis of the current IMO COLREGS.

 

What is a Sternlight?Sternlight on a bunker tanker

  • White light
  • Placed as nearly as practicable at the stern
  • Showing an unbroken light over an arc of the horizon of 135 degrees
  •  So fixed as to show the light 67.5 degrees from right aft on each side of the vessel

What is a Towing light?

  • Yellow light
  • Same characteristics as the sternlight

 

What is an all-round light?

  •  A light Showing an unbroken light over an arc of the horizon of 360All-round lights degrees

What is a Flashing light?

  • A light flashing at regular intervals at a frequency of 120 flashes or more per minute

Why are the arcs of navigation not given in rounded numbers of degrees?

The arcs of navigation lights are based on the traditional mariners compass. In this each ‘point’ is 1/32 of a circle, which is 11.25 degrees.  The change in arch between Masthead lights/Sidelights and the sternlight occures at 2 points abaft the beam, that is 22.5 degrees.

The Navigation Light Definitions and the Rest of The COLREGS

Two vessel situations are defined within the Rules by the aspects of their navigation lights; a crossing situation is implied by being neither of these.

Overtaking-Rule 13

A vessel overtaking when coming up with another vessel from a direction Power Driven Vessel from Asternmore than 22.5 degrees abaft her beam, that is, in such a position that at night she would be able to see only the sternlight of that vessel but neither of her sidelights.

Head on (Power-driven vessels)-Rule 14Power Driven vessel end on

A head on situation exists when a vessel sees the other ahead or nearly ahead and by night she could see the masthead lights of the other in a line or nearly in a line and/or both sidelights, and by day she observes the corresponding aspect of the other vessel.

 


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Navigation Lights-Power Driven Vessels

Navsregs>COLREGS>Power Driven Vessel

It is time to start a new series of posts, a series that returns to explore COLREGS. The series of posts will start its  dive into the Navigation Light Rules with the most common set of lights seen deep sea, a power-driven vessel of  50  metres in length underway.

Note: These posts will not reproduce the Rules word perfect, so please refer to copy of the Regulations for the original wording.

Power Driven Vessel Lights

What Rule covers power driven vessels underway?

RULE 23 Power-driven Vessels Underway

It is important to note when interpreting this Rule two of the definitions in Rule 3, namely

  • That Power-driven vessel means any vessel propelled by machinery
  • Underway means that a vessel is not at anchor, or made fast to the shore, or aground

What is contained in Rule 23?

  • (a) What a power driven Vessel Underway must exhibit
  • (b) What an air cushion vessel should exhibit
  • (c) What a power driven vessel of less than 12 metres in length should exhibit

What lights must a power driven vessel underway show?Power Driven vessel end on

  • Masthead light forward
  • A second masthead light abaft of and higher than the forward one; a vessel of less than 50 meters in length shall not be obliged to exhibit such light but may do so
  • sidelights
  • A stern light

The lights of smalI power driven vessels

Of less than 12 meters in length

May insted of the masthead lights and side lights lights exhibit an all-round white light and sidelights.

Of less less than 7 meters in length whose maximum speed does not exceed 7 knots

May exhibit an all round white light instead of masthead, side and stern lights, but shall, if practicable, also exhibit sidelights.

How may the positioning of the lights of a power driven vessel less than 12 meters in length differ?

The masthead light or all-round white light may be displaced from the fore and aft centerline of the vessel if centerline fitting is not practicable, as long as the sidelights are combined in one lantern which shall be carried on the fore and aft centerline of the vessel or located as nearly as Power Driven Vessel from Asternpracticable in the same fore and aft line as the masthead light or the all-round white light.

The size requirements list simplified

  • 50m: Two masthead lights required
  • 12m: May combine masthead and stern lights in all round light
  • 7m/7knts: May replace all the lights with an all round light

The next post will look at the meanings of the key terms in Rule 23.


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