Aids to Navigation
Written by Peter Buxbaum
CGF 2010 Volume: 2 Issue: 6 (November)
The Coast Guard has enhanced the performance
and endurance of its navigation system, increasing
intervals between maintenance and allowing
ATON personnel to perform other duties.
The coastal and inland waters of the United States are marked by the U.S. Aids to Navigation (ATON) to assist mariners and boaters. ATON, a system installed and maintained by the U.S. Coast Guard, has the goal of promoting safe navigation on waterways. It provides navigators with the same type of information automobile drivers get from street signs: stop signals, road barriers, detours and traffic lights. The aids themselves include lighthouses, minor lights, day beacons, range lights, sound signals, and lighted and unlighted buoys. Each helps in determining vessel location, navigating from one place to another, or avoiding danger.
The primary components of the U.S. Aids to Navigation System are beacons and buoys. Beacons are structures that are permanently fixed to the earth’s surface. They range from lighthouses to small structures and may be located on land or in the water. Beacons exhibit a day mark to make them readily visible and easily identifiable against background conditions. Generally, the day mark conveys to the boater during daylight hours the same significance as the aid’s light or reflector at night.
Buoys are floating aids of various shapes and sizes. They are moored to the seabed by concrete sinkers with chain or rope moorings connected to the buoy’s body. They are intended to convey information to mariners and boaters by their shape or color, by the characteristics of a visible or audible signal—and sometimes with a radar or radio signal—or a combination of two or more such features.
Multiple Functions
The Coast Guard for some years has endeavored to drive efficiencies to the ATON system, including the introduction of solar power to the lighted ATONs. This has allowed ATON tending equipment and personnel to participate in significant ways in other Coast Guard missions.
“Installing and maintaining the aids to navigation system is one of the Coast Guard’s 11 statutory missions,” said Commander Greg Tlapa, program manager at the Coast Guard’s Visual Aids to Navigation Directorate.
There are five objectives of the ATON system, Tlapa added. “They are used to assist navigators to determine their position,” he explained. “They assist in determining a safe course and warn navigators of obstructions. They promote safe movement of commercial vessel traffic and they promote the efficient movement of military traffic and cargo of strategic importance.”
In all, ATON serves the safety needs of some 30,000 commercial vessels and 13 million recreational boaters. Fifty-thousand federal aids—13,000 of which are located in the Mississippi River and its tributaries—are supplemented by an additional 50,000 private aids to navigation that the Coast Guard licenses and regulates.
“Eighty percent of U.S. exports and imports, totaling 2.6 billion tons annually, move by water,” said Tlapa. “Without ATON, commerce would grind to a halt.” The various aids to navigation are placed in locations requiring the specific capabilities offered by each. “Seagoing buoys are exposed to everything the ocean has to offer,” he noted. “They measure 18 by 26 feet and weigh 15,000 pounds when fully outfitted. Smaller buoys can weigh as little as 100 pounds and are usually unlit. They are deployed in more sheltered areas such as bays and harbors that are less exposed and somewhat protected.”
Fixed beacons and lights range from a single pile with a day board or day board and light, to historical lighthouses located on the point of a peninsula and whose light has a 30-mile range out to sea. Some ATON stations—121 to be exact—are equipped with radar beacons, also known as racons. “When a vessel makes a sweep past one of the stations and the radar interrogates the unit, it activates a pulse from the racon unit that appears on the navigator’s radar screen,” explained Tlapa. “A navigator can deconflict different radar contacts to determine which is an aid to navigation.”
A racon is a radar transponder which, on receiving a radar signal, automatically transmits a particular radar signal in reply, identifying itself and enabling navigators of ships to determine their distance and direction from it. Racons add navigational information to a common marine radar, causing the radar to display a locally unique code on its screen. With this information, the mariner can measure the distance between his ship and the racon, measure the direction to the racon, and, with a local nautical chart, accurately determine his or her own position.
Racons are located most often at the entrance to a major shipping channel. “A handful of racons are located as fixed aids on large shoreside structures,” said Tlapa. “But most are attached to sea buoys. A mariner returning from a seagoing voyage making his way to the entry point of the San Francisco Bar Channel, for example, can readily identify the first buoy mariner on the radar and can make for the pilot station and proceed in.” The Bar Channel is located outside of San Francisco Bay, five miles west of the Golden Gate.
Monitor and Control
Tideland Signal Corporation has supplied SeaBeacon racons to the U.S. Coast Guard since 1991 and is the current USCG racon supplier. Tideland is under contract to supply over 200 of the latest model, the SeaBeacon 2 System 6 racons, according to Jody Sturtze, the government sales manager for the Houstonbased manufacturer.
Tideland has also supplied the Coast Guard with units that monitor and control the racons. The Coast Guard has an automated Aids Control and Monitoring System (ACMS) of lighthouses and Short Range Aids to Navigation (SRAN) sites equipped with remote monitor and control systems that are monitored by operations centers. Tideland has supplied over 100 of its MC-1 units to the Coast Guard.
“These units are capable of receiving and processing input signals from Coast Guard equipment being monitored,” said Sturtze. “They then send messages over a cell phone line to central control centers. We have worked closely with Coast Guard personnel at C2CEN [the Coast Guard Command, Control, and Communications Engineering Center] in training and operations of the system.” The MC-1s are located primarily in lighthouses on the eastern seaboard.
The Coast Guard is currently testing Tideland’s V-Track V-03 Informer, an automatic identification system (AIS) device similar to those required by the Coast Guard to be outfitted on most oceangoing vessels. “The Coast Guard has acquired two of these devices,” said Sturtze. “One has been installed in a channel in the port of New Orleans and the other will be installed on a buoy in New York harbor. The devices transmit AIS information to mariners in the area.” Tideland also supplies the Coast Guard with thousands of its ML-155 Marine Signal Lantern which is used to mark buoys, structures and channels.
Ionomers
Gilman Corporation, a manufacturer headquartered in Gilman, Conn., is a leading supplier to the Coast Guard of navigational buoys fashioned from ionomer foam. Ionomers are very high-grade polymers manufactured by DuPont and Exxon, which are known for their high performance characteristics when the resin is extruded as a foam. Ionomer foam is known for its toughness, flexibility and low-density. Gilman custom manufactures ionomers into various products, including navigational aids.
The U.S. Coast Guard began switching its steel buoys for foam ones in the 1990s. “These buoys are extremely lightweight, they exhibit excellent damage resistance and retain their color throughout the life of the buoy,” noted a publication of the International Association of Lighthouse Authorities. “[They] have been developed into very useful aids to navigation, are very adaptable to special locations and can be modified for lighting equipment. Response from Coast Guard field units and local mariners has been very positive. The ionomer foam buoys remain brighter than steel or plastic buoys … do not sink or crush, do not severely damage pleasure boats during collisions, require smaller mooring equipment and minimal maintenance, and perform very well in high current areas.”
In addition to the Coast Guard, Gilman provides its products— ionomer foam channel marks, marine buoys and regulatory buoys—to the Canadian Coast Guard, China, France and Thailand, and commercial ports and waterways all over the world.
Robust Enhancements
Enviro Float Manufacturing of Saanichton, British Columbia, manufactures foam navigation buoys that are encapsulated in high density polyethylene. These features, said company president Jim Fletcher, make the buoys stronger and more environmentally friendly. “Nothing sticks to them, they don’t break up, they don’t sink,” said Fletcher. “Encapsulated foam creates a more robust structure, substantially increasing its working life. With encapsulation, the biggest benefit is the absence of foam breakdown [that would] result in loss of buoyancy.”
The Coast Guard has endeavored to enhance the efficiency of its aids to navigation, increasing the intervals between maintenance and stretching the capabilities of personnel who tend to them. Incandescent lighting has been replaced with lightemitting diodes (LEDs), solid state devices which boast much longer useful lights than ordinary light bulbs. A large proportion of lighted ATON devices are now powered by the sun.
“LEDs continue to give you the same light output but with a smaller power capacity footprint, and solar power eliminates batteries,” said Bob Trainor, an ATON specialist who works with Tlapa. “Incandescent lighting systems have complicated cable and power systems. LEDs are self-contained and don’t require as much human interaction. There are fewer potential failure points.”
Tideland Signal Corporation is currently under contract to supply the Coast Guard with LED retrofit kits, which will be used in their RL-14 Range Lantern housings, to replace the current mirror and incandescent lamp assemblies. “The LED kits have adjustable intensity controls, meeting or exceeding the Coast Guard’s intensity requirements from 2,000 to 95,000 candles,” said Sturtze.
The transition of the ATON inventory to solar power has been ongoing for 20 years. “We are now 97 percent solarized,” said Trainor. “We have been able to get rid of primary batteries and we no longer have to dispose of batteries. The Coast Guard embraced green technology pretty early on.”
Other improvements include better buoy coatings and better color codings on day boards. “We’ve made dramatic improvements so they don’t have to be touched so often,” said Tlapa. “We have also improved our practices and doctrine on board ship, on how we station vessels and position buoys. It now takes much less time to position the buoys and they stay out longer.” The ATON system is serviced by 3,300 Coast Guard personnel, stationed on board 76 65-foot cutters and at 58 shoreside ATON stations. The improvements made to ATON operations, said Tlapa, represent a “huge success story in leveraging the multimission capability of the ATON fleet with a backdrop of the efficiency improvements to our ATON inventory.”
Multitasking
The ATON cutters are equipped with cranes and derricks to enable the crew to lift devices out of the water and place them back after performing maintenance on the deck. But the cutters and the crew are by no means confined to performing ATON maintenance.
“These 76 ships are not one-trick ponies,” said Tlapa. “I would argue they are the most capable multimission vessels in the Coast Guard. They actively engage in search and rescue missions; they are involved in living marine resources enforcement and in pollution response operations. On the Great Lakes they do ice breaking, and elsewhere, they have been involved in drug interdictions.”
Most recently, the ATON fleet was heavily involved in responding to the Deepwater Horizon disaster in the Gulf of Mexico, performing tasks such as dragging booms and skimming oil. “We sent half of our seagoing buoy tenders and a quarter of our coastal buoy tenders down there for undetermined periods of time,” said Tlapa. “Eight of the seagoing buoy tenders and four of the coastal buoy tenders are still down there. This raises a question about what is not getting done back at home.”
The answer is that the Coast Guard’s work for the last 10 years in driving efficiencies to the ATON infrastructure “paid for our ability to participate in the Deepwater Horizon operations so robustly,” said Tlapa.
“Ten or 15 years ago, if the ATON fleet were called upon to respond, the legacy ATON inventory would not as likely have fared as well,” Tlapa added. “But in this case, our capabilities were sustained at a very high level, even with our cutters deployed in the gulf.” ♦