Lights, buoys - navigation aids. (2023)

navigation aids

Navigationshilfen, „navaid“- also known asNavigationshilfe „AtoN“– are special structures such as lighthouses, lightships, beacons, buoys that are used to increase security by providing more opportunities to get LOPs.
In contrast:navigation toolsincluding parallel rulers, dividers, GPS / Galileo / GLONASS plotters, radar, compasses, paper charts and sextants.

Lights and markings are mandated worldwide by the International Association of Lighthouse Authorities (IALA). 1977 thatIALAadvocated two maritime buoy systems, putting an end to the then 30 odd systems.

  • Area Bincludes America (incl. Canada), Japan, the Philippines and Korea.
  • Area Aincludes Europe, Australia, New Zealand and the rest of the world.

Fortunately, the differences between these two systems are small. The most striking feature is thedirection of the buoyancy force.

All navigation aids within IALA are characterized by:

  • Form
  • Licht
  • Color
  • record

to form

The standardBojenformenare cylindrical (can)Lights, buoys - navigation aids. (2), conical (nun)Lights, buoys - navigation aids. (3), sphericalLights, buoys - navigation aids. (4), PillarLights, buoys - navigation aids. (5)and savingsLights, buoys - navigation aids. (6), but variations occur, e.g. barrelLights, buoys - navigation aids. (7).

beacon– which are mostly solid and not floating – only have an elongated and upright shape. The shape of the top mark is essential.

Easy identification

During the day, the identification of navigational aids is made by observing:Location,Form,color scheme,auxiliary functions(Ton signals,RACON) ormarkings(name, number, etc.).

But during the night we use the functions of the AtoNsLichtTobothidentify and determine its purpose. There are three characteristics to describe the light:

  • Color: eitherWWeiss,RRot,GGreen,YGelb,Ororange orTheBlau.
    If no color is specified in the table, the default is white.
    On regular cards, a white, red, yellow, or green light shows throughLights, buoys - navigation aids. (8), while on displays and modern multicolored maps in certain colors, such asLights, buoys - navigation aids. (9), where the yellow colored lobe indicates aWeiss light, or if marked Y, a yellow light.
  • Period: the time in seconds required for a complete change cycle.
    Lights, buoys - navigation aids. (10)
    For example, the marker shows the 10 second period of the two flashes, including 8 seconds of darkness of a "Fl (2) 10s" light.
    Except in particular FL (5) 20s , Q (9) 15s and Q (6) + LFL 15s practically all lights have a period of 3½ - ½ s.
  • phase characteristic: the particular pattern of changes within a complete cycle (that is, within a period). The faster the changes, the more important (or larger) the hazard covered by the light.

Typical lights with color, period and phase characteristics:

Lights, buoys - navigation aids. (11)LFL 10s

Lights, buoys - navigation aids. (12)Q(3) G 9s

Lights, buoys - navigation aids. (13)ISO 6s

Lights, buoys - navigation aids. (14)F Fl Y 5s

Lights, buoys - navigation aids. (15)Ok 5s

Lights, buoys - navigation aids. (16)Al WR 4s

(Video) Ep 39: Understanding Navigational Aids

Lights, buoys - navigation aids. (17)Mon (U) 8s "You are steering a dangerous course", e.g. near offshore facilities.

list of lights

All illuminated navigation aids are eithersignificantorirrelevantLights where principal lights are used for important navigation points along seacoasts, canals, and harbor and river entrances:nominal rangeover 10 nm.

If not included in the map, important details such as color, structure, base, range, height, of itmain lightssee an important reference calledlight listorlist of lights.

Examples of such "light lists" areNGA (World),USA,France (World),You have,Admiralty (world),Denmark & ​​Greenland,Norway,Island,Brazil,New Zealand, etc.

Little Lightsare found in harbours, along canals and rivers and are of low to moderate intensity: nominal range less than 10 NM.
The range of lights on buoys is never shown on the chart (Super paintare the exception) or in a light list.
On a clear night - and without a backlight - the maximum distance at which an illuminated marker can be seen is about 3 NM, but often less than 1 NM.
Small harbor lights have a nominal range of 1 to 3 NM.

below, aexcerpt from thePdfshows the IALA barrel system:

Favorite channel markers

When a fairway splits into a main and a side fairway, "preferred fairway buoys" may be used, indicating whether the fairway is to starboard or to port.

These buoys have both red and green colors, but the main color is that for the main channel, while the color for the side channel is just a stripe.

The light phase characteristic is FL (2+1) with the light color of the main channel.

cardinal sign

The four configurations of cardinal buoys indicate the safe side of a hazard with an approximate bearing. For example, Cardinal Buoy West has safe water on its west side and danger on its east side.

Body: black and yellow horizontal band(s); pillar or spar.

Topmark: two black cones, the tips of which point towards the black bands on the body of the buoy (or beacon), for example for a north cardinal sign the black band is at the top.
As with theisolated danger sign, the Topmark is not optional.

Lights: white fast flashing or very fast flashing.

Note the similarity of the dial in light phase characteristics:
3 o'clock is east
6 o'clock is south, plus a long flash
9 o'clock is west.

Isolated danger sign

Scattered hazard markers are posted over hazards with navigable water around them.

(Video) Navigation buoyage-lights & buoys , EDITION # 05

These buoys are rarely used in sandy regions like the Netherlands or Germany.
A typical hazard that justifies an "isolated hazard label".on topof which is a lonely rock.
In contrast, cardinal buoys indicate directionawayahead of the hazard and are often used for hazards that cover larger objects or areas such as wrecks, shoals or reefs.

Body: black with red horizontal bands; pillar or spar.

Topmark: 2 black balls, not optional.

Lights, buoys - navigation aids. (21)

New danger sign

After the sinking of thetricolor” in the Pas de Calais (Strait of Dover) in 2002 several other vessels struck the wreck despite standard radio warnings, three watch vessels and a lighted buoy.

Lights, buoys - navigation aids. (22)

This incident spawned a new type of buoy, theMarker buoy for emergency wrecks, which is placed as close as possible to a new dangerous wreck.

The emergency wreck marker buoy will remain in position until:

  • the wreck is known and has been published in nautical publications;
  • the wreck has been fully surveyed and precise details such as position and shallowest depth over the wreck are known; And
  • a permanent marking of the wreck has been carried out.

Body: yellow and blue longitudinal stripes; Pillar or spar, size dependent on location.

Topmark: a standing / upright yellow cross

Licht: Al Oc Bu Y 3s
Blau 1,0 s + 0,5 s + Gelb 1,0 s + 0,5 s = 3,0 sLights, buoys - navigation aids. (23)

When multiple buoys are deployed, the lights are synchronized.
A raccoon Morse code "D" and / orAIStransponders are used.

Special mark

Markings used to indicate a particular area or feature, the nature of which may be apparent from reference to a chart or other nautical publication. They are generally not intended to mark channels or obstructions where other markers are more appropriate.

Lights, buoys - navigation aids. (25)

Body: yellow, any shape not contradictinglateral markings.

Topmark: single yellow "×" shape

(Video) Lateral Buoys Explained { NEW TRICKS }

Light: yellow, for example Fl Y or Fl(4) Y, but any rhythm other than that used for white lightCardinal,isolated dangerorsecure watermarks.

Used for ODAS cable / pipelines, recreation zones, boundaries (from anchorages), military training zones, renewable energy facilities and aquaculture.

Areas - leading lines

Leading lights and ranges

AAreaconsists of two or more fixed navigation marks, some distance apart and at different elevations. When these are illuminated they are called conventionalleading lightsbecause "range" also applies to distances (immersion range, headlight range, geographic range, etc.).

The shape and color of the day marks and the colors and characters of the lights are advertised in the "List of Lights".

Examples of full light descriptions

Lights, buoys - navigation aids. (26)

Fl(3) class light: Group flashing that repeats a group of three flashes

WRG. Colors: white, red, green, showing the different colors in specific sectors

15s Period: the time it takes to show a complete sequence of 3 flashes and eclipses: 15 seconds

21m Height of the focal plane above the reference point: 21 Meter

15-11M nominal ranges: white 15 m, green 11 m, red between 15 and 11 m (nautical miles, NM or M)

Lights, buoys - navigation aids. (27)

Fl(3)AndF.R. class lights: Group flashing of three flashes (main light visible from all directions), no color displayed, hence white. Second, a solid red sector light aimed over a hazard10s Period: the time it takes to show a complete sequence of 3 flashes: 10 seconds. Obviously, the solid light has no period62mAnd55m Height of the focal planes above the reference point: 62 meters for the all-round fire and deeper at 55 meters the red sector fire

25MAnd12M nominal ranges: white 25 and red 12 nautical miles

When sailing on a dangerous course and within 12 NM both the white flashing light and the red steady light can be seen in a vertical line one above the other.

directional lights

Directional lights (or directional lights) are explained in. These lights are a very narrow sector intended to mark a direction to be followed. They are generally used where beacons cannot be placed but serve the same purpose as beacons.

visibility of lights


It's important to know at what distance we see (start) seeing a particular light and when to expect to lose sight of it, especially when we hit land. Several practical scopes are used to describe the visibility of lights in navigation:

  • headlight range- maximum distance at which a given light signal can be seen by the observer's eye at a given time, determined by the prevailing meteorological visibility at that time.
    It doesn't take into account the height of the light, the eye level of the viewer, or the curvature of the earth.
    The table below shows that atmosphere immensely affects the visibility of light passing through it.

The international standards for describing reduced visibility in ocean forecasts are as follows:
Very poor: <0,5 NM
Arm: 0,5 – 2 NM
Moderate: 2 – 5 NM
Gut: >5 NM

  • rated range- the headlight range with a meteorological daytime visibility of 10 NM, which corresponds to a transmission of 74%. The nominal range is generally the number used in official documents such as nautical charts, fire registers, etc. The rated range assumes the fire is observed against a dark background with no backlight.
    If not specified in the table, consult the list of luminaires.
  • The headlight range is the effective nominal range in atmospheric visibilitynot10 sm.

  • Thegeographic reachis based on the light level, the viewer's eye level and the curvature of the earth.
    A higher light means its horizon is farther away, you seedistance of the horizondistance of the horizon.
    Similarly, if the observer's eye level is higher than sea level, the light can be seen beyond that geographic range → thediving areadiving area.

So a light - perched on a 70m high cliff - with a geographical range of 20 NMnotbe recognizable by the human eye (eye level 2m) at a distance of 6 NM if ...

  1. ...the nominal range is only 5 NM because the light is not very bright.
  2. ...the headlight range is only 5 NM, due to a "light haze".

headlight range diagram

This chart gives the approximate distance at which a fire can be sighted at night given the prevailing meteorological visibility at the time of observation

(Video) Navigation Buoys - Lights & Shapes | Superyacht International

The chart is entered from the top with the nominal range given in the nautical chart or "List of Lights".

The numbers along the curves represent the estimated meteorological visibility at the time of observation, and the numbers along the left border the headlamp range under those conditions.

Example: Consider a light with an intensity of 100,000 candelas, which corresponds to a nominal range of about 20 NM.
With a meteorological visibility of 20 NM, the fire could be sighted at about 32 miles (navy colored line, 1 arrow) and at about 6 NM (navy colored line, 2 arrows) at sufficient altitude and eye level at 2 NM.

Since the scale at the top is based on a meteorological visibility of 10 NM, this results in the headlight ranges under the prevailing conditionsclearlyThe 10 mile curve is identical to the rated range starting at the upper limit.

The chart can also be used to get an approximate meteorological visibility; For example, if a light with an intensity of 100,000 candelas is sighted at 12 NM, the current meteorological visibility is about 5 NM.

CautionWhen using this chart, keep the following in mind:

  • The ranges obtained are approximate.
  • The transparency of the atmosphere is not necessarily consistent between the observer and the light.
  • Glare from backlighting will significantly reduce the area where lights are seen. A 100,000 candela light has a nominal range of 20 NM; with low background light, such as from a populated coast, this range is reduced to around 14 NM and with strong background light, such as from a city or port facilities, to around 9 NM.

Lower margin: CandelasTo get approximate visibility distances, enter the chart with the listed intensity divided by 10 for low backlight and 100 for high backlight.

Geographic Reach

A light's geographic range depends on the altitude of both the light and the viewer.

The sum of the observer's distance to the visible horizon (based on their eye level) plus the light's distance to the horizon (based on their elevation) is their geographic range, which is thediving areadiving area.

Geographic reach = 2.08 × (√height + √eye height)

The formula can be simplified and solved without a calculator. Assume a convenient standard eye height of 4 meters and round 2.08 to 2.

2 × (√Höhe + 2)

Example with a light height of 25 meters:

2 × (5 + 2) = 14 nautical miles

Download theRange table (PDF)orgeographic range table (PNG)or use mineonline calculator.

See theGeographic range tableor use mineonline calculator.

Visible Range

When comparing geographic range to the light's range, the smaller of the two ranges is the distance at which the light is first sighted: thevisible area.

Draw a visibility arc centered on the light and with a radius equal to the visible area. Extend that of the vesseldead reckoningdead reckoningtrace until it intersects the visibility arc.
The bearing from the intersection to the light is the predicted bearing of the light when first sighted.

A light rock

Upon first sighting a light, an observer can tell if it is on the horizon by immediately lowering their eye level. If the light disappears and then reappears when the observer returns to its original altitude, the light is at the horizon. This process is called "swimming a light".

High tide or no tide...

Some judgment is required (headlight range is a rough estimate), resulting in a large margin of error in the visible range. Therefore, it should be necessary to include the tide when the light level is rather low (<20 m) and the tidal range is high.


Due to the limiting factor of geographic range, most main lights are never seen from a sailing yacht 20 nautical miles away. However, due to atmospheric dispersion, it is sometimes possible to take a compass bearing on theloomof light: its reflection against the clouds. Additionally, it is sometimes even possible to observe arotatingbeam of light.

Lights, buoys - navigation aids. (28)Lights, buoys - navigation aids. (29)
loom Immersion distance &hairsp;/&hairsp;range

Colors have different ranges

Different colored lights with sameluminosityhave different ranges.
White light is the most visible, followed by yellow, green, and red.
Therefore, an "AL WG" can resemble a "Fl W" at extreme distances.&hairsp;&hairsp;

Removal of the stray light

The range of an illuminated buoy is never given, but on a clear night the maximum range is 3 NM, but often considerably less.

There are 2 visual cues to determine your distance from a buoy: at around 0.5nm the light rises from the horizon and at around 200m the light is reflected off the surface.

Lights, buoys - navigation aids. (30) Lights, buoys - navigation aids. (31) Lights, buoys - navigation aids. (32)
Buoy at less than 3 NM Buoy at less than 0.5 NM Buoy at less than 200 m


  • loom: the diffuse glow observed from a light below the horizon due to atmospheric scattering of its light rays, usually at the base of clouds.
  • emerging: an apparent elevation of distant terrestrial objects by abnormal atmospheric refraction. Due to the surfacing, objects below the horizon are sometimes visible. The opposite is the “sink” in low visibility.
  • ENZ: the electronic navigation chart.
  • ECDIS: the electronic map display and information system.
  • AIS navigation aids: AtoN automatic identification system
    • Real AISAtoN attaches to a physical marker such as a lighthouse or buoy.
    • Synthetic AISAtoN is also connected to a physical marker, but the actual AIS transmitter is in a different location.
    • Virtual AISAtoN marks the hazard with the coordinates of the hazard, but there is no physical light, no buoy.
  • ODES-Boje: Ocean Data Acquisition Systems Buoy – means a buoy intended for the collection of data on ocean properties. It can be moored or free floating.
  • Navigationshilfe (AtoN)orNavigationshilfe (NAVAID): any marking, sign, device or system external to a ship designed and operated to assist in determining position, defining a safe course, or warning of danger, traffic or obstructions.
  • rated rangeis the light range with a meteorological visibility of 10 NM, which corresponds to a transmission factor of T=0.74.
  • Geographic Reachis the maximum distance at which an object or light from a light source can theoretically be seen by an observer, limited only by the curvature of the earth, the refraction of the atmosphere, the height of the object or light, and the height of the observer's eye.
  • headlight rangeis the maximum distance at which a given signal light can be seen by the observer's eye at any given time, determined by the intensity of the prevailing meteorological visibility at that time. It does not take into account the viewer's height, eye level, or the curvature of the earth.
    Example - a light with an intensity of 500 candela (nominal range of about 8 NM) can be seen up to 12 NM when the meteorological visibility is 20 NM, but is only seen at 3 NM when the meteorological visibility is 2 NM.
  • Visible Range: the extreme distance at which a luminous object can be seen, given the current eye level and current meteorological visibility: the smaller of the luminous and geographic ranges.
  • A light rock: Rapidly lowering the eye level and raising it again when a navigation light is first sighted to determine if the observer is within the light's geographic range.
  • headlight range diagram: Diagram for converting the nominal range of a luminaire into its beam range under existing conditions.
  • Meteorological Optical Codes: Ranks from 0 (dense fog: less than 50 meters visibility) to 9 (exceptionally clear: more than 27 kilometers visibility).
  • Signs, sea marks, navigation marks: an object, man-made or natural, of easily recognizable shape or color or both, located in such a place that it can be identified on a map. A fixed artificial navigation mark is often denoted as an abeacon.
  • light properties: the sequence and length of light and dark periods and the color or colors by which a navigation light is identified.
  • record: one of several objects with a characteristic shape, placed on a buoy or beacon to facilitate its identification.
  • Lateral marking: AtoN is intended to mark the sides of a canal or waterway.
  • cardinal sign: black and yellow AtoN is intended to indicate the location of a hazard for navigation based on its position relative to the hazard using the cardinal points of the compass: north, east, south and west, each with distinctive double-cone topmark variations. When lit, the Q or VQ group flashes resemble the face of a clock.
  • Isolated danger sign: AtoN marks a hazard with clear water all around; It has a double ball topmark and is black with at least one red band. When lit, its characteristic is Fl(2).
  • sector light: a fixed AtoN that displays a light of different colors and/or rhythms over specific arcs. The color of the light gives directional information.
  • Light Sector: defined by seaward bearings, the sector where a navigation light is visible, or where it has a distinct color difference from adjacent sectors, or where it is obscured.
  • lighthouse: a tower or substantial building or structure erected in a specific geographic location to carry a signal light and provide a significant mark of the day. It provides a long or medium range light for nighttime identification.
  • low light: a light with a nominal range of <10 NM. An automatic unmanned fire at a fixed structure, usually showing low to medium intensity. Small lights are placed in harbors, along canals, along rivers and at isolated danger spots.
  • big light: a light with a nominal range of >10 NM. A light of high intensity and reliability that is exhibited from a fixed structure (lighthouse) or on marine terrain (except beacons). Main lights include primary coastal and secondary lights.
  • light list: a detailed list of navigational aids, including lighthouses and other illuminated navigational aids, unilluminated buoys, radio beacons, day beacons, and raccoons.
  • landing: the first sighting of land by eye or radar when approaching from the seaward side.
  • Area: two or more objects (leading brands) in a line. Such objects should be within range. An observer who has them within range is said to be "on range line" or "on track". Two beacons are often positioned together for the specific purpose of forming an area to indicate a safe route or the center line of a canal.
  • leading line: a straight solid line drawn through leading marks (an area) on the chart. A ship moving along such a line will eliminate certain hazards or stay in the best waters.
  • Leading Lights: two or more lights at different heights, arranged to form a line and its guiding line when passing through. The one closest to the viewer is the taillight and the one farthest from the viewer is the taillight. The front light is at a lower level than the rear light.
  • lights in line: two or more lights arranged to be observed when passing through aPosition: the boundary of an area, an alignment used for anchoring, etc. Not to be confused with beacons, which mark a recommendationDirectionto follow.


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