What are 5 aids to navigation?

Marker to assist in safe passage making

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"ATON" redirects here. For other uses, see Aton

The entrance to the inner harbour of the Port of Fremantle, Australia, with a yellow special mark at left, a region A red port lateral mark at right, and a region A green starboard lighthouse in the background

A navigational aid (NAVAID), also known as aid to navigation (ATON), is any sort of signal, markers or guidance equipment which aids the traveler in navigation, usually nautical or aviation travel. Common types of such aids include lighthouses, buoys, fog signals, and day beacons.

Definition

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According to the glossary of terms in the United States Coast Guard Light list, an aid to navigation (ATON) is any device external to a vessel or aircraft specifically intended to assist navigators in determining their position or safe course, or to warn them of dangers or obstructions to navigation.

Lateral marks

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Region B green port lateral marks (with Galápagos sea lions (Zalophus wollebaeki)) in the Galápagos Islands

Lateral marks indicate the edge of the channel. The standards are defined by the International Association of Marine Aids to Navigation and Lighthouse Authorities (IALA). Approaching harbour port a vessel leaves port hand marks to port (left) and starboard hand marks to starboard (right). Port hand marks are cylindrical, starboard marks are conical. If the mark is a pillar or spar shape, then a topmark is fitted which is either cylindrical or conical as appropriate.[1]

IALA divides the world into two regions: A and B. Region B is the Americas (excluding Greenland) along with Japan, Korea and the Philippines. Region A is the rest of the world. In region A port marks are red and starboard marks green. In region B port marks are green and starboard red.[1] Where marks are numbered red marks have even numbers and green marks have odd numbers.

Preferred channel marks

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Where a channel divides the mark at the junction is called a "preferred channel mark" or "junction buoy". The mark has the colour and shapes corresponding to the preferred channel with a band of the other colour to indicate it is the other hand mark for the subsidiary channel.[1] In IALA region A where a minor channel branches off to port the mark at the junction would be a red cylinder with a green band. The red cylinder is a port hand mark for the main channel, the green band indicates a starboard mark for the minor channel. In IALA region B the colours (but not shapes) are reversed.

Cardinal marks

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Cardinal marks warn of a danger (wrecks, shoals, bends, spits etc.) and indicate the safe water past the danger. There are four varieties: north, east, south and west. A north cardinal mark is placed to the north of a hazard and indicates safe water is to the north of the mark. East, south and west are placed accordingly. Cardinal marks are yellow and black with two cones at top marks. There is no difference between IALA region A and B.

Other IALA defined marks

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Isolated danger mark

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Black with a horizontal red band and two black balls as a top mark. The mark indicates a danger (shoal, rock, wreck etc.) which is isolated with safe water all around.

Safe water mark

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Red and white vertical stripes with a single red sphere for a top mark. It indicates that there is safe water all around it. The usual use is to indicate the start of a channel or port approach.

New danger

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Indicates a newly discovered or created danger that is not yet marked on charts (or in update notices thereto). The mark is used for a short time until the danger is either removed or else marked conventionally with lateral or cardinal marks. The mark has blue and yellow vertical stripes and a yellow and blue light. The topmark is a vertical yellow cross.

Special marks

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Yellow with an "X" topmark. Used to mark other features such as swimming areas, anchorages, pipelines. The exact reason is marked on charts.

Sector lights

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A sector light is one which shows different colours depending upon the angle of approach. They are commonly used to indicate the safe channel (white) and show red or green if the vessel is out of the safe channel. IALA requires the light colours to follow the appropriate region (A or B) colour scheme.

Other markers

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Diagram showing lateral, non-lateral, and special purpose markers as seen on an IALA Region B nautical chart.

There are also other markers that give information other than the edges of safe waters. Most are white with orange markings and black lettering. They are used to give direction and information, warn of hazards and destructions, mark controlled areas, and mark off-limits areas. These ATONs do not mark traffic channels.

On non-lateral markers, there are some shapes that show certain things:

Squares[10]

show information, including places to find food, supplies, and repairs. They sometimes show directions.

Diamonds[10]

warn about dangers like rocks, construction, dams, or stumps.

Circles[10]

mark a controlled area such as no wake, idles speed, speed limit, or ski zone.

Crossed diamonds[10]

show areas off limits to all boats, like swimming areas and dams.

AIS AtoNs

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AtoNs can be integrated with automatic identification system (AIS). AIS transmitted form an actual aid (buoy, lighthouse etc.) is termed a "real AIS AtoN".[11]

If it is impractical to equip the AtoN with an AIS transponder an AIS shore station can be assigned to transmit AIS messages on behalf of the AtoN. This is known as a "synthetic ATON". Synthetic AtoNs can be either "monitored synthetic AtoNs" or "predicted synthetic AtoNs". The former have a link between the AtoN so that the AIS station can confirm the AtoNs status. The latter have no link and the AIS system just predicts that the AtoN is where it should be.

If there is no real AtoN (such as for the short term marking of a wreck) then a "virtual AIS AtoN" is used.

Each AIS AtoN must have a unique Maritime Mobile Service Identity (MMSI) number. Synthetic and virtual AIS AtoNs mark their messages as repeats to indicate that the location of the transmitter is not the location of the AtoN.

Lead marks and lights

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Triangle shaped lead marks with lights.

Lead marks (as in "leading a ship into a safe place") and lights are fixed markers that are laterally displaced to allow a mariner to navigate a fixed channel along the preferred route. They are also known as "channel markers".[14][failed verification] They can normally be used coming into and out of the channel. When lit, they are also usable at night. Customarily, the upper mark is up-hill from the lower (forward) mark. The mariner will know the geometry of the marks/lights from the navigational chart and can understand that when "open" (not one above the other) the ship needs to be navigated to "close" the marks (so one is above the other) and be in the preferred line of the channel.

In some cases, the lead marks/lights are provided by lasers, as in the laser channel under the Tasman Bridge on the Derwent River at Hobart, Tasmania.

See also

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Notes

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Further reading

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Visual ATON Signals - IALA Maritime Buoyage System

This online article is an advisory summary of different ATON marks. For detailed recommendations refer to IALA Maritime Buoyage System.

Regions

Buoyage system has been geographically divided into two regions; A and B. Lateral marks differ between Buoyage Regions A and B, and other five types of marks are common.

Image source

ATON Marks

Lateral marks indicate the edge of a channel.  In a river, the direction of buoyage is towards the river's source and in a harbour, the direction of buoyage is into the harbour from the sea. Red and green colors mark the port (left-hand) and starboard (right-hand) sides of channel in Region A, and reversed colors red to starboard and green to port in Region B. Therefore the area between red and green buoy is a safe route for a vessel to navigate. In some regions also bifurcation buoys are used to mark out the preferred channel.

Cardinal marks are different shaped yellow-black sea marks with top-mark. They indicate the direction of safe waterway, cardinal (compass) direction (north, east, south or west) relative to the mark. Cardinal mark can also indicate of a hazard.

Isolated danger mark is black-red colored and placed on or near to a danger. Safe water mark, also called a Fairway buoy is red-white colored and indicates navigable water around it. Special marks are yellow and they indicate a special area for example cables, pipelines, spoil ground, aquaculture or recreation zone. New danger marks are newly discovered hazards and wrecks that may not be shown in nautical documents. They are blue-yellow.

For marking different ATON applications around the world we offer a wide selection of buoy lanterns including both standalone (externally powered) and solar self-contained lanterns.

Self-contained solar lantern M650H on a red buoy.

Other marks are visual ATON signals assisting mariners in the navigation and not necessarily mark channel limits or obstructions.

1. Leading lines/ranges Leading lights, also referred to as range lights, are beacons that are used both day and night to mark safe passage for vessels along a fairway, through a shallow or dangerous channel, or when entering ports. They provide precise analog visual feedback to determine the vessel&#;s location relative to the center of the channel. Leading lines can be any color or shape that provides a distinctive mark from the background, determined by competent authority.
   
   LO200M range lights marking the leading line.
2. Sector lights display different colors and/or rhythms and the color of the light provides directional information to the mariner. Omnidirectional sector lights can cover multiple fairways with a single installation. They can also be used to mark out very wide sectors. When AtoN lighting needs to provide extremely precise guidance only projector sector lights can deliver the required accuracy. Some models of projector sector light can include an oscillating boundary. It gives more information of position near the sector boundary to the mariner by creating a light character with alternately flashing colours to further help the mariner to obtain his lateral position related to the mid of the safe channel.
   
   For more detailed guidance on choosing right marine lantern for specific applications see our QUICK GUIDE ATON SIGNALS focusing on sector, leading and PEL lights.
   
   
   

   Sector light ODSL 200  with different colored sectors cover multiple fairways at a same time.

3. Lighthouses are towers or substantial structures which show a signal light by night and operate as a significant daymark during daytime. Lighthouse structures can be of any color, shape or material.

   
   

   Rotating lighthouse beacon VRB-25

   combines LED technology with traditional rotating beam.
   

   
   
   

   Sabik Lighthouse Unit SLU modernizes the technology of the traditional lighthouses while preserving the historic heritage and look.

4. Beacons and other short range ATON are fixed navigation marks that can be of for example different shapes, colors and patterns. They can carry a signal light or operate unlit only as a daymark.
   
   LED 160

   on a fixed beacon in a large commercial port.

   
   
   
5. Major floating aids include for example light vessels or large navigational buoys. They are deployed at critical locations with a heavy shipping traffic to mark approach from offshore areas. They can also be a plaform for other ATON such as AIS.
   
   

   Lightvessels act as lighthouses in waters that are unsuitable for fixed constructions.

6. Auxiliary Marks are other minor ATON marks that are not previously described. They do not mark routes or obstructions and they are usually outside defined channels. They are used to assist navigation and convey information for general navigational safety.
   
   

   Auxililiary mark indicating cable lines in Finland.

7. Port or harbor marks are local marking measures like bridge lights and port traffic signals. Before transiting an area for the first time, mariners should be aware of local ATON marking.
   
   

   Sabik all-round LED 160 lanterns as bridge lights.

This online article is an advisory summary of different ATON marks. For detailed regulations refer to IALA Maritime Buoyage System; definitions and descriptions regarding each of the above marks, their color, shape, top mark, numbering, synchronization and light rhythm on full document R IALA Recommendation IALA Maritime Buoyage System downloadable.   

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