Aids to Navigation

Navigation Aid Basics

Unlike the roads and highways that we drive on, the waterways we go boating on do not have road signs that tell us our location, the route or distance to a destination, or of hazards along the way. Instead, the waterways have AIDS TO NAVIGATION (or ATONs), which are all of those man-made objects used by mariners to determine position or a safe course.

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These aids also assist mariners in making a safe landfall, mark isolated dangers, enable pilots to follow channels, and provide a continuous chain of charted marks for precise piloting in coastal waters. The U.S. Aids to Navigation System is intended for use with nautical charts, which provide valuable information regarding water depths, hazards, and other features that you will not find in an atlas or road map.

The term "aids to navigation" includes buoys, day beacons, lights, lightships, radio beacons, fog signals, marks and other devices used to provide "street" signs on the water. Aids To Navigation include all the visible, audible and electronic symbols that are established by government and private authorities for piloting purposes.

The Coast Guard is the agency responsible for maintaining aids to navigation on U.S. waters that are under federal jurisdiction or that serve the needs of the U.S. armed forces. On bodies of water wholly within the boundaries of a single state, and not navigable to the sea, the Coast Guard grants the state responsibility for establishing and maintaining aids to navigation. The U.S. Corps of Engineers is responsible for many of the canals, dams, locks, and other man-made waterways in the country. The Corps also is responsible for the regulation of mooring buoys in all navigable U.S. Waters.

The individual Coast Guard districts also may grant permission to private groups and citizens to place "Private" Aids to Navigation. These aids allow individuals or organizations the ability to mark privately maintained channels, zones or waterways. These aids must be pre-approved, and must be maintained by the individual or organization.

Types of Aids to Navigation

The term "aids to navigation" encompasses a wide range of floating and fixed objects (fixed meaning attached to the bottom or shore), and consist primarily of:

• Buoys - floating objects that are anchored to the bottom. Their distinctive shapes and colors indicate their purpose and how to navigate around them.
• Beacons - structures that are permanently fixed to the sea-bed or land. They range from structures such as light houses, to single-pile poles. Most beacons have lateral or non-lateral aids attached to them. Lighted beacons are called "LIGHTS", unlighted beacons are "DAYBEACONS".

Both Buoys and Beacons may have lights attached, and may have a sound making device such as a gong, bell or horn. Both Buoys and Beacons may be called "marks".

Caution: Do not count on floating aids to always maintain their precise charted positions, or unerringly display their characteristics. The Coast Guard works constantly to keep aids on station and functioning properly, but obstacles to perfect performance are so great that complete reliability is impossible. Only use floating aids for use as a navigation fix when you cannot see a fixed point of reference.

Aids to Navigation Systems

Depending on where you boat in America, you may see several differences in how navigational marks are colored, numbered, or lighted. Regardless of the location, buoys and beacons are placed in very specific locations, to mark either a particular side of a waterway, or some other navigational feature. The primary system in use is referred to the "U.S. Aids to Navigation System". The U. S. Coast Guard maintains this system in conformance to the International Association of Lighthouse Authorities (IALA), which is an international committee which seeks to ensure safe navigation, primarily through the use of common navigation aids and signals.

The "LATERAL" system is the familiar RED RIGHT RETURNING system, meaning that on all navigable waters returning from sea, the red even-numbered marks are on the starboard (right) side of the channel and the green odd-numbered marks are on the port (left) side of the channel. Numbers on the marks ascend when traveling from sea to harbor--if you don't have a compass and become disoriented on the water, you will always know you are heading upstream if the buoy numbers get larger as you travel.

Port Side Odd Numbered Aids

Port side numbered aids are green in color, odd numbered and may be lighted. Port side marks are located on the left side of the waterway as you travel upstream, and the buoy numbers will increase as you head upstream. (Chart depictions are shown next to the marks) Port-Side Buoys have a cylindrical above-water appearance, like a can or drum floating on its axis. Commonly referred to as "CAN" buoys. Beacons - Port side beacons have square marks attached to them, with two shades of color and a reflective border.

Starboard Side Even Numbered Aids

Starboard aids are red in color, evenly numbered and will be on your right side as you travel upstream. Buoy numbers increase as you head upstream, and may have a red light. Starboard-side buoys have an above-water appearance like that of a cylinder topped with a cone, pointed end up. The cone may come to a point or be slightly rounded. Commonly referred to as "NUN" buoys. Starboard-side Beacons have triangular marks attached to them, with two shades of color and a reflective border.

Intracoastal Waterway

For the sea buoys that delineate channels off the coast of the United States, and for the Intracoastal Waterway (ICW), red is on the right (shore side) when proceeding clockwise around the U. S. from the East Coast to the Gulf Coast, or proceeding north along the West Coast.

ICW marks are further identified by a small yellow reflector at the bottom of the mark. The same port and starboard marks shown above will look like the following.

Numbers on the marks ascend when traveling in this direction. Where the IALA-B and ICW marks meet, one must be very careful to observe the change in meaning by referral to local charts.

Other Aids - Marks

Dayboards

These diamond shaped marks are used to help the vessel operator determine location on a nautical map. When you see a dayboard, and find the corresponding mark on the chart, you know your precise location. They may be lettered, and may be lighted with a white light. Their color reflects that of nearby lateral marks.

Safe Water Marks

These marks are used to mark fairways, mid-channels, and offshore approach points. They have unobstructed water on all sides. These marks may be lettered, and may be lighted with a white light. They may also have a red top mark.

Isolated Danger Marks

These indicate a danger which may be passed on all sides. They are erected on, or moored on or near danger. They should not be approached closely without special caution. They may be lighted, and they may be lettered.

Special Marks

Special marks have no lateral significance (meaning they don't tell you which side of the channel or river you may be on). These marks are used to mark a special feature or area. These include area limits for anchorages, fishing grounds, or dredging/spoil areas. These buoys may be lighted, and if they are it will be a fixed or flashing yellow light. Shape is optional, but usually follows the shape of the navigation buoys that it is positioned near.

Other Aids - Miscellaneous

Mooring Bouys

Mooring buoys come in two different shapes; spherical and cylindrical. Both have white bodies with a solid blue horizontal band on the center of the buoy. Mooring buoys may have a white reflector, or a white light attached to them. Mooring buoys are the ONLY buoys to which you may legally tie your boat. Buoys are generally placed in marked anchorage areas, and you must take caution if you are traveling near buoy areas. Check your state boating guide for particular operating restrictions in anchorage areas.

Ranges

These are pairs of unlighted or lighted fixed aids that when observed in line show the pilot to be on the centerline of a channel.

Regulatory Marks

Regulatory Marks re designed to assist boaters by informing them of special restrictions or dangers that they are approaching. Regulatory marks are white "can" buoys that have an orange shape on them. The mark will give either a warning or instructions on how to proceed. The shape determines what type of mark it is.

• An open diamond shape signifies danger.
• A diamond with a cross in it signifies an exclusion area that you may not enter.
• A circle indicates an upcoming operating restriction, such as a speed limit.
• A square or rectangular shape is used for conveying instructions.

Uniform State Waterway Marking System

This system was originally intended for use by states on lakes and inland waterways that weren’t covered by nautical charts. The buoys used in the Uniform State Waterway Marking System (USWMS) used colors, shapes and marking patterns that differed greatly from the U.S. Aids to Navigation System (ATONS).

In 1998, the U.S. Coast Guard decided to phase out the USWMS to avoid potential confusion of boaters and instead, favored using the more widely recognized ATONS. By 2003, the USWMS was completely phased out. Below are a few of the differences from the federal system you should know about.

Here's a summary of the important changes regarding the phase out of USWMS:

• The old USWMS black port side channel markers are now GREEN can buoys.
• The old USWMS red starboard side channel markers are now red NUN buoys.
• The old USWMS red and white vertically striped buoys have been replaced by one of the following: a red or green channel marker directing safe passage, an orange and white regulatory marker, or a red and black isolated danger marker.
• The old USWMS white buoys topped with black or red bands, have been replaced by one of the following: a red or green channel marker directing safe passage, an orange and white regulatory marker, or a red and black isolated danger marker.

Lateral Aids

The state system differs in several ways, in case you happen to encounter them. These aids also assist mariners in making a safe landfall, mark isolated dangers, enable pilots to follow channels, and provide a continuous chain of charted marks for precise piloting in coastal waters. The U.S. Aids to Navigation System is intended for use with nautical charts, which provide valuable information regarding water depths, hazards, and other features that you will not find in an atlas or road map.

• Buoys are placed in pairs, and you pass between them.
• State buoys do use the color red for starboard side marks, but they are cans, and not nuns, while port buoys are black and can-shaped.
• Numbers on buoys go up as you head upstream, or towards the head of navigation.
• Portside buoys use the color black instead of green.
• Portside buoys are numbered with odd numbers.
• Portside buoys may show a green reflector or light.
• Starboard side buoys are red.
• Starboard side buoys are numbered with even numbers.
• Starboard side buoys may show a red reflector or light.

Other State Aids

Red-topped White Buoys

• Signify that you may pass south or west of buoy
• May be numbered
• May show a white reflector or light

Black-striped white Buoys - Inland Waters Obstruction Mark

• Signify that you should not pass between mark and nearest shore
• May be lettered
• May show white reflector or light
• Replaces the old red and white vertically striped buoy

Black-topped White Buoys

• Signify that you may pass east or north of buoy
• May be nubered
• May show white reflector or light

Marker to assist in safe passage making

"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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