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.
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:
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".
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 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 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.
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.
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.
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.
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 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.
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.
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 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.
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 , 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 , 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 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.
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Red-topped White Buoys
Black-striped white Buoys - Inland Waters Obstruction Mark
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The officer of the watch on the bridge of a modern cargo ship or cruise liner is responsible for the safe navigation of these giants of the sea. They rely on an array of navigational technology to safely find their way and avoid collisions with other ships or natural obstacles. But how has navigational technology advanced in the past 50 years?
Even in the s and s, ships already had some impressive modern technology available. The increasing accuracy and reliability of gyrocompasses had made error-prone magnetic compasses obsolete except as a backup. Gyrocompasses rely on a rapidly spinning gyroscope to detect the rotation of the earth and point towards the centre of rotation at the North Pole.
The widespread use of radar onboard ships, originally developed for military application started to find application in civilian ships from the s. This was a major advance allowing ships officers to effectively see in the dark or even in thick fog or low cloud. Later, Automatic Radar Plotting Assistance was added to help make sense of complex traffic situations by keeping track of objects the radar had picked up.
VHF radio was widely adopted and allowed ship-to-ship and ship-to-shore voice communication, replacing signal flags and semaphore. To fix the ship’s position, radio direction finding was used. Hyperbolic radio-fixing systems such as LORAN-A and DECCA were considered the state of the art in navigational technology. By triangulating the bearing of radio signal transmitters at known locations, the ship’s navigator was able to fix the ship’s position down to the accuracy of approximately one nautical mile, even in the open ocean. These radio-fixing aids simplified the navigator’s problem of determining how far from land the ship was but did not do much for precise coastal pilotage. Skilled local pilots with the ability to steer the ship from visual marks with knowledge of local currents and hazards remained critical to safe navigation.
The s and s saw rapid developments in ships and shore-based technology. Global attention was focused on the environmental consequences of shipping accidents by a number of high-profile and severely damaging groundings and oils spills. Notable examples among these were the SS Torrey Canyon grounding and spill of more than 100 million litres of oil on the south coast of the UK, and the Amoco Cadiz spill of 256 million litres of oil on the beaches of Brittany. In Canada, the groundings and spills of the SS Arrow (, 10 million litres) and SS Kurdistan (, 6 million litres) drew attention to shipping risks in Chedabucto Bay and Cabot Strait.
In response, Traffic Separation Schemes (TSS) were established, commencing in with the Dover Straits (mandatory in ) and now extending to all areas of major marine traffic confluence. TSS, as the name suggests, create a system of separated one-way traffic lanes. The routes are established through the IMO Convention on the International Regulations for Preventing Collisions at Sea (COLREGs), and implemented through national regulation, help to streamline traffic flow, reduce crossing and heads-on meeting situations, thus significantly reducing the risk of collision. The value of TSS continues to be recognized with new TSS being added each year to the list sanctioned by the IMO. The IMO established the TSS in the Strait of Juan de Fuca in and Canada now has 5 mandatory and 7 recommended routing systems.
In conjunction with TSS, Vessel Traffic Services (VTS) were established to provide oversight of vessel movements. This was pioneered in Liverpool and Rotterdam in and respectively and was implemented in the very busy Dover Straits by . VTS were initially quite rudimentary, comprising manual radar surveillance and radio call-in points for ship self-reporting. In recent years VTS have been augmented by digital ship tracking and sophisticated computer algorithms for highlighting collision and grounding risks. Trained VTS operators aid safety of navigation by alerting ships to dangers and providing a critical interface with search and rescue, pollution and other marine response agencies.
Onboard the ship also saw revolutionary changes in technology in the s and s, starting with the development of satellite navigation systems in the s.
The US Navy’s TRANSIT navigation system of determining terrestrial positions by cross-fixing obtained from radio Doppler-shifts was made available for civilian use and then superseded in the s by the more accurate Global Positioning System (GPS), which determines distance by precise time differences. In the year , all users were given access to the highest accuracy service when the military disabled a system they had been using to degrade accuracy for civilian users called Selective Availability.
The increased accuracy led to the explosion of geographic information systems (GIS) and georeferenced applications in all aspects of civilian life. Modern navigation systems now have access to American, European, Russian and Chinese satellite constellations simultaneously which allows them to accurately fix positions to within less than one metre. The combined constellation of technologies has been recognized with the acronym GNSS – Global Navigation Satellite Systems.
These high degrees of navigational precision provided by GNSS was complemented by the digitization of paper charts through Electronic Nautical Charts (ENC). The combination creates the ability for mariners to precisely view their position in space on the chart through an Electronic Chart Display and Information Systems (ECDIS). The result is highly accurate, fully automatic electronic navigation available both commercially and recreationally.
Ships still had to rely on radar, radio communication or visual observations to detect other ships until the advent of Automatic Identification Systems (AIS). AIS is a system of automated VHF radio transmissions that exchanges between ships key identification and navigational data such as a ship name, IMO number, type of ship, destination, activity/status (underway, anchored, fishing, etc.) position, course, and speed. The information is displayed on the ship’s navigation system (radar or ECDIS) as symbology with leaders to indicate true and relative movement. In this way, the navigator is able to correlate ships with radar contacts, and to immediately identify them for bridge-to-bridge radio communications in resolving collision avoidance situations. This same technology has also aided marine safety with the use of Virtual Aids to Navigation (V-AtoN) to highlight navigational hazards or temporary exclusion zones. These are navigational warnings or dangers transmitted to the ship’s radar/chart plotters as symbology, showing apparent contacts through AIS technology without the need for a physical object like a warning buoy.
The cross-referencing of radar and geographic (charted) information on both radars and ECDIS, combined with AIS, gives navigators the ability to make risk assessments and decisions based on accurate and complete information, even in low visibility conditions. It is even possible for ships to follow planned tracks through the use of autopilots. Such autopilots can operate in three modes: course maintaining, track-following, and route-following. Most ships use the first, with the bridge watchkeeper making adjustments for track following, maintaining personal awareness of the ship’s set and drift. Almost always in situations of critical pilotage or complex traffic, and in heavy seas, ships will revert to hand steering for greater control and quicker response.
Communication technology also advanced significantly in the last few decades of the 20th century. Increasing prevalence of mobile data connections has created the opportunity for real-time acquisition of weather, wind, bathymetry, water-level and air-gap data through localized networks. Satellite communication initially opened the door to voice communication even when outside of the range of VHF radio. Increasingly, satellite communication is used for data. Lower-cost satellite internet brought about by low-earth orbit satellite technology (e.g., Starlink, Telesat or Iridium) means that modern ships can now have access to real-time data sources over extended ranges, subject to satellite coverage and service subscription.
The baseline of navigational equipment in ocean-going ships varies by tonnage. The table below summarizes required navigational equipment in accordance with Canada’s Navigational Safety Regulations (NSR) , which mirror the IMO’s SOLAS Chapter V requirements.
While the standard set of technologies varies depending on size of the ship measured in gross tonnes, the common technologies for even small ships (GPS, ECDIS, Automatic Radar Plotting Assistance, radars, AIS, autopilot, satellite communications and internet connectivity) is a very significant step up from the mid-60s, at which time even large, modern ships were being navigated on paper charts with rudimentary radio navigation aids, with hand-plotted collision avoidance on simple radars.
The trend in digitalization and connected technology seen in ships has also been mirrored in the technology deployed by the pilots who board the ships to safely navigate them through the challenging waters close to port. Portable Pilotage Units (PPU) are personal tablet computers carried by the pilot, and they replace the detailed course books that the pilots in the s and 70s carried with them. PPUs give the marine pilot a reliable, accurate and independent source of navigation information. Previous to the introduction of PPU’s, pilots were reliant on the ship’s fitted equipment (gyros, radars, echo sounders, paper charts, etc.), augmented by visual navigation enabled by memorization of courses, leading marks, clearing bearing and other traditional pilotage methods. The key benefit of PPU’s is the availability to the pilot of highly accurate positional and navigation information that enables precise navigation independent of any possible faults or failures in the ship’s fitted systems. With cellular data connection or ship Wi-Fi, there is now also a possibility of integrated live feeds of current local hydrographic information such as water levels.
The safety record of international shipping has advanced dramatically since the early s when the global fleet would lose 1 ship in every 100 to sinking according to data collected by Lloyd’s Register. Nowadays these types of accidents are extremely rare, with only 38 ships lost in in a global fleet of more than 130,000 .
Since the era of paper charts and sextants, navigation technologies have undergone a remarkable transformation. Satellite navigation systems, sophisticated radar, electronic charts and real-time communications are just some of the innovations that have revolutionized the way ships navigate at sea.
These technological advances have not only improved navigational safety, but also optimized the efficiency of maritime operations. Ships can now navigate on more precise routes, reducing fuel consumption and emissions. Vessel traffic management systems and vessel tracking technologies enable better coordination and visibility of movements, reducing the risk of collision.
As we look to the future, the horizon for navigation technology looks even brighter. Artificial intelligence, machine learning and augmented reality have the potential to further transform marine navigation, making it even safer, more efficient and more sustainable.
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