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CHAPTER 5

SHORT RANGE AIDS TO NAVIGATION

DEFINING SHORT RANGE AIDS TO NAVIGATION

500. Terms and Definitions

Short range aids to navigation are those intended to beused visually or by radar while in inland, harbor andapproach, and coastal navigation. The term encompasseslighted and unlighted beacons, ranges, leading lights,buoys, and their associated sound signals. Each short rangeaid to navigation, commonly referred to as a NAVAID, fitswithin a system designed to warn the mariner of dangersand direct him toward safe water. An aid’s functiondetermines its color, shape, light characteristic, and sound.This chapter explains the U.S. Aids to Navigation Systemas well as the IALA Maritime Buoyage System.

The placement and maintenance of marine aids tonavigation in U.S. waters is the responsibility of the United

States Coast Guard. The Coast Guard maintalighthouses, radiobeacons, racons, sound signals, buoand daybeacons on the navigable waters of the UniStates, its territories, and possessions. Additionally, tCoast Guard exercises control over privately ownenavigation aid systems.

A beaconis a stationary, visual navigation aid. Larglighthouses and small single-pile structures are bobeacons. Lighted beacons are calledlights; unlightedbeacons aredaybeacons. All beacons exhibit adaymarkof some sort. In the case of a lighthouse, the color and tyof structure are the daymarks. On small structures, thedaymarks, consisting of colored geometric shapes caldayboards, often have lateral significance. The markingon lighthouses and towers convey no lateral significance

FIXED LIGHTS

501. Major and Minor Lights

Lights vary from tall, high intensity coastal lights tobattery-powered lanterns on single wooden piles.Immovable, highly visible, and accurately charted, fixedlights provide navigators with an excellent source forbearings. The structures are often distinctively colored toaid in identification. See Figure 501a.

A major light is a high-intensity light exhibited froma fixed structure or a marine site. Major lights includeprimary seacoast lights and secondary lights.Primaryseacoast lightsare major lights established for makinglandfall from sea and coastwise passages from headland toheadland.Secondary lightsare major lights established atharbor entrances and other locations where high intensityand reliability are required.

A minor light usually displays a light of low tomoderate intensity. Minor lights are established in harbors,along channels, rivers, and in isolated locations. Theyusually have numbering, coloring, and light and soundcharacteristics that are part of the lateral system of buoyage.

Lighthousesare placed where they will be of most use:on prominent headlands, at harbor and port entrances, onisolated dangers, or at other points where mariners can bestuse them to fix their position. The lighthouse’s principalpurpose is to support a light at a considerable height abovethe water, thereby increasing its geographic range. Support

equipment is often housed near the tower.With few exceptions, all major lights operate automa

ically. There are also many automatic lights on smallstructures maintained by the Coast Guard or othattendants. Unmanned major lights may have emergengenerators and automatic monitoring equipment to increathe light’s reliability.

Light structures’ appearances vary. Lights in low-lyinareas usually are supported by tall towers; conversely, ligstructures on high cliffs may be relatively short. Howeveits support tower is constructed, almost all lights asimilarly generated, focused, colored, and characterized

Some major lights use modern rotating or flashinlights, but many older lights useFresnel lenses. Theselenses consist of intricately patterned pieces of glass inheavy brass framework. Modern Fresnel-type lensescast from high-grade plastic; they are much smaller alighter than their glass counterparts.

A buoyant beaconprovides nearly the positional ac-curacy of a light in a place where a buoy would normally bused. See Figure 501b. The buoyant beacon consistsheavy sinker to which a pipe structure is tightly moored.buoyancy chamber near the surface supports the pipe.light, radar reflector, and other devices are located atoppipe above the surface of the water. The pipe with its buoancy chamber tends to remain upright even in seveweather and heavy currents, providing a smaller watch c

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64 SHORT RANGE AIDS TO NAVIGATION

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cle than a buoy. The buoyant beacon is most useful alongnarrow ship channels in relatively sheltered water.

502. Range Lights

Range lightsare light pairs that indicate a specific lineof position when they are in line. The higher rear light isplaced behind the front light. When the mariner sees thelights vertically in line, he is on the range line. If the frontlight appears left of the rear light, the observer is to the rightof the range line; if the front appears to the right of the rear,the observer is left of the range line. Range lights aresometimes equipped with high intensity lights for daylightuse. These are effective for long channels in hazyconditions when dayboards might not be seen. The rangelight structures are usually also equipped with dayboardsfor ordinary daytime use. Some smaller ranges, primarily inthe Intercoastal Waterway, rivers, and other inland waters,have just the dayboards with no lights. See Figure 502.

To enhance the visibility of range lights, the Coast

Guard has developed 15-foot long lighted tubes calledlightpipes. They are mounted vertically, and the mariner sethem as vertical bars of light distinct from backgrounlighting. Installation of light pipes is proceeding on severrange markers throughout the country. The Coast Guardalso experimenting with long range sodium lights for arerequiring visibility greater than the light pipes can provide

The output from a low pressure sodium light is almoentirely at one wavelength. This allows the use of ainexpensive band-pass filter to make the light visible evduring the daytime. This arrangement eliminates the nefor high intensity lights with their large power requirement

Range lights are usually white, red, or green. Thedisplay various characteristics differentiating them frosurrounding lights.

A directional light is a single light that projects a highintensity, special characteristic beam in a given directionis used in cases where a two-light range may not be pracable. Adirectional sector light is a directional light thatemits two or more colored beams. The beams have a p

Figure 501a. Typical offshore light station.

Figure 501b. Typical design for a buoyant beacon.

SHORT RANGE AIDS TO NAVIGATION 65

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cisely oriented boundary between them. A normalapplication of a sector light would show three colored sec-tions: red, white, and green. The white sector wouldindicate that the vessel is on the channel centerline; thegreen sector would indicate that the vessel is off the channelcenterline in the direction of deep water; and the red sectorwould indicate that the vessel is off the centerline in thedirection of shoal water.

503. Aeronautical Lights

Aeronautical lights may be the first lights observed atnight when approaching the coast. Those situated near thecoast and visible from sea are listed in theList of Lights.These lights are not listed in the Coast GuardLight List.They usually flash alternating white and green.

Aeronautical lights are sequenced geographically in theList of Lightsalong with marine navigation lights. However,since they are not maintained for marine navigation, they aresubject to changes of which maritime authorities may not beinformed. These changes will be published inNotice toAirmen but perhaps not inNotice to Mariners.

504. Bridge Lights

Navigational lights on bridges in the U.S. are prescribedby Coast Guard regulations. Red, green, and white lights

mark bridges across navigable waters. Red lights mark piand other parts of the bridge. Red lights are also useddrawbridges to show when they are in the closed positioGreen lights mark open drawbridges and mark the centerlof navigable channels through fixed bridges. The position wvary according to the type of structure.

Infrequently-used bridges may be unlighted. In foreigwaters, the type and method of lighting may be different frothose normally found in the United States. Drawbridges whimust be opened to allow passage operate upon sound andsignals given by the vessel and acknowledged by the bridThese required signals are detailed in the Code of FedeRegulations and the applicableCoast Pilot. Certain bridgesmay also be equipped with sound signals and radar reflect

505. Shore Lights

Shore lights usually have a shore-based power suppLights on pilings, such as those found in the IntracoasWaterway, are battery powered. Solar panels may be instato enhance the light’s power supply. The lights consist ofpower source, a flasher to determine the characteristic, a lachanger to replace burned-out lamps, and a focusing lens

Various types of rotating lights are in use. They do nhave flashers but remain continuously lit while a lensreflector rotates around the horizon.

The aids to navigation system is carefully engineer

Figure 502. Range lights.


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to provide the maximum amount of direction to the marinerfor the least expense. Specially designed filaments andspecial grades of materials are used in the light to withstandthe harsh marine environment.

The flasher electronically determines the charac-teristic by selectively interrupting the light’s power supplyaccording to the chosen cycle.

The lamp changer consists of several socketsarranged around a central hub. When the circuit is brokenby a burned-out filament, a new lamp is rotated intoposition. Almost all lights have daylight switches whichturn the light off at sunrise and on at dusk.

The lens for small lights may be one of several types.

The common ones in use are omni-directional lenses155mm, 250mm, and 300mm diameter. In addition, lighusing parabolic mirrors or focused-beam lenses are useleading lights and ranges. The lamp filaments mustcarefully aligned with the plane of the lens or mirror tprovide the maximum output of light. The lens’ size ichosen according to the type of platform, power source, alamp characteristics. Additionally, environmental charateristics of the location are considered. Various typeslight-condensing panels, reflex reflectors, or colored secpanels may be installed inside the lens to provide the procharacteristic. A specially reinforced 200mm lanternused in locations where ice and breaking water are a haz

LIGHT CHARACTERISTICS

506. Characteristics

A light has distinctive characteristics whichdistinguish it from other lights or convey specificinformation by showing a distinctive sequence of light anddark intervals. Additionally, a light may display adistinctive color or color sequence. In theLight Lists, the

dark intervals are referred to aseclipses.

An occulting light is a light totally eclipsed at regularintervals, the duration of light always being greater than theduration of darkness. Aflashing light flashes on and off at

regular intervals, the duration of light always being lesthan the duration of darkness. Anisophaselight flashes atregular intervals, the duration of light being equal to thduration of darkness.

Light phase characteristics (See Table 506) are tdistinctive sequences of light and dark intervals osequences in the variations of the luminous intensity olight. The light phase characteristics of lights which chancolor do not differ from those of lights which do not changcolor. A light showing different colors alternately isdescribed as analternating light. The alternating charac-teristic may be used with other light phase characteristic

TYPE ABBREVIATION GENERAL DESCRIPTION ILLUSTRATION*

Fixed F. A continuous and steady light.

Occulting Oc. The total duration of light in a period islonger than the total duration of darknessand the intervals of darkness (eclipses)are usually of equal duration. Eclipseregularly repeated.

Group occulting Oc.(2) An occulting light for which a group ofeclipses, specified in number, is regularlyrepeated.

Composite groupocculting

Oc.(2+1) A light similar to a group occulting lightexcept that successive groups in a periodhave different numbers of eclipses.

Isophase Iso A light for which all durations of light anddarkness are clearly equal.

Table 506. Light phase characteristics.


Flashing Fl. A light for which the total duration oflight in a period is shorter than the totalduration of darkness and the appearancesof light (flashes) are usually of equalduration (at a rate of less than 50 flashesper minute).

Long flashing L.Fl. A single flashing light for which anappearance of light of not less than 2 sec.duration (long flash) is regularly repeated.

Group flashing Fl.(3) A flashing light for which a group offlashes, specified in number, is regularlyrepeated.

Composite groupflashing

Fl.(2+1) A light similar to a group flashing lightexcept that successive groups in a periodhave different numbers of flashes.

Quick flashing Q. A light for which a flash is regularlyrepeated at a rate of not less than 50flashes per minute but less than 80 flashesper minute.

Group quickflashing

Q.(3) A light for which a specified group offlashes is regularly repeated; flashes arerepeated at a rate of not less than 50flashes per minute but less than 80 flashesper minute.

Q.(9)

Q.(6)+L.Fl.

Interrupted quickflashing

I.Q. A light for which the sequence of quickflashes is interrupted by regularlyrepeated eclipses of constant and longduration.

Very quickflashing

V.Q. A light for which a flash is regularlyrepeated at a rate of not less than 80flashes per minute but less than 160flashes per minute.




Group very quickflashing

V.Q.(3) A light for which a specified group of veryquick flashes is regularly repeated.

V.Q.(9)

V.Q.(6)+L.Fl.

Interrupted veryquick flashing

I.V.Q. A light for which the sequence of veryquick flashes is interrupted by regularlyrepeated eclipses of constant and longduration.

Ultra quickflashing

U.Q. A light for which a flash is regularlyrepeated at a rate of not less than 160flashes per minute.

Interrupted ultraquick flashing

I.U.Q. A light for which the sequence of ultraquick flashes is interrupted by regularlyrepeated eclipses of constant and longduration.

Morse code Mo.(U) A light for which appearances of light oftwo clearly different durations aregrouped to represent a character orcharacters in Morse Code.

Fixed and flashing F.Fl. A light for which a fixed light is combinedwith a flashing light of greater luminousintensity

.

Alternate light Al. A light showing different colorsalternately

* Periods shown are examplesonly.

NOTE: Alternating lights may be used in combinedform with most of the previous types of lights




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Light-sensitive switches extinguish most lightednavigation aids during daylight hours. However, owing tothe various sensitivities of the light switches, all lights donot turn on or off at the same time. Mariners should accountfor this when identifying aids to navigation during twilightperiods when some lighted aids are on while others are not.

507. Light Sectors

Sectors of colored glass or plastic are sometimesplaced in the lanterns of certain lights to indicate dangerouswaters. Lights so equipped show different colors whenobserved from different bearings. A sector changes thecolor of a light, but not its characteristic, when viewed fromcertain directions. For example, a four second flashingwhite light having a red sector will appear as a four secondflashing red light when viewed from within the red sector.

Sectors may be only a few degrees in width or extendin a wide arc from deep water toward shore. Bearingsreferring to sectors are expressed in degrees true asobserved from a vessel. In most cases, areas covered by redsectors should be avoided. The nature of the danger can bedetermined from the chart. In some cases a narrow sectormay mark the best water across a shoal, or a turning pointin a channel.

The transition from one color to another is not abrupt.The colors change through an arc of uncertainty of 2° orgreater, depending on the optical design of the light.Therefore determining bearings by observing the colorchange is less accurate than obtaining a bearing with anazimuth circle.

508. Factors Affecting Range and Characteristics

The condition of the atmosphere has a considerable effectupon a light’s range. Lights are sometimes obscured by fog,haze, dust, smoke, or precipitation. On the other hand,refraction may cause a light to be seen farther than underordinary circumstances. A light of low intensity will be easilyobscured by unfavorable conditions of the atmosphere. Forthis reason, the intensity of a light should always be consideredwhen looking for it in thick weather. Haze and distance mayreduce the apparent duration of a light’s flash. In someconditions of the atmosphere, white lights may have a reddishhue. In clear weather green lights may have a more whitishhue.

Lights placed at higher elevations are more frequentlyobscured by clouds, mist, and fog than those near sea level.In regions where ice conditions prevail, an unattendedlight’s lantern panes may become covered with ice or snowThis may reduce the light’s luminous range and change thelight’s observed color.

The distance from a light cannot be estimated by itsapparent brightness. There are too many factors which can

change the perceived intensity. Also, a powerful, distalight may sometimes be confused with a smaller, closer owith similar characteristics. Every light sighted should bcarefully evaluated to determine if it is the one expected

The presence of bright shore lights may makedifficult to distinguish navigational lights from backgroundlighting. Lights may also be obscured by various shoobstructions, natural and man-made. The Coast Gurequests mariners to report these cases to the nearest CGuard station.

A light’s loom is sometimes seen through haze or threflection from low-lying clouds when the light is beyondits geographic range. Only the most powerful lights cagenerate a loom. The loom may be sufficiently definedobtain a bearing. If not, an accurate bearing on a ligbeyond geographic range may sometimes be obtainedascending to a higher level where the light can be seen, anoting a star directly over the light. The bearing of the stcan then be obtained from the navigating bridge and tbearing to the light plotted indirectly.

At short distances, some of the brighter flashing lighmay show a faint continuous light, or faint flashes, betwe

regular flashes. This is due to reflections of a rotating leon panes of glass in the lighthouse.

If a light is not sighted within a reasonable time afteprediction, a dangerous situation may exist. Conversely,light may simply be obscured or extinguished. The shipposition should immediately be fixed by other meansdetermine any possibility of danger.

The apparent characteristic of a complex light machange with the distance of the observer. For examplelight with a characteristic of fixed white and alternatinflashing white and red may initially show as a simplflashing white light. As the vessel draws nearer, the rflash will become visible and the characteristic wiapparently be alternating flashing white and red. Later, tfainter fixed white light will be seen between the flasheand the true characteristic of the light finally recognizedfixed white, alternating flashing white and red (F W Al WR). This is because for a given candlepower, white is tmost visible color, green less so, and red least of the thrThis fact also accounts for the different ranges given in tLight Lists for some multi-color sector lights. The samlamp has different ranges according to the color impartby the sector glass.

A light may beextinguisheddue to weather, batteryfailure, vandalism, or other causes. In the caseunattended lights, this condition might not be immediatecorrected. The mariner should report this condition to thnearest Coast Guard station. During periods of armconflict, certain lights may be deliberately extinguishewithout notice. Offshore light stations should always be lewell off the course whenever searoom permits.


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BUOYS

509. Definitions and Types

Buoys are floating aids to navigation. They markchannels, indicate shoals and obstructions, and warn themariner of dangers. Buoys are used where fixed aids wouldbe uneconomical or impractical due to the depth of water.By their color, shape, topmark, number, and light character-istics, buoys indicate to the mariner how to avoid hazardsand stay in safe water. The federal buoyage system in theU.S. is maintained by the Coast Guard.

There are many different sizes and types of buoysdesigned to meet a wide range of environmental conditionsand user requirements. The size of a buoy is determinedprimarily by its location. In general, the smallest buoywhich will stand up to local weather and current conditionsis chosen.

There are five types of buoys maintained by the CoastGuard. They are:

1. Lateral marks2. Isolated danger marks3. Safe water marks4. Special marks5. Information/regulatory marks

These conform in general to the specifications of theInternational Association of Lighthouse Authorities(IALA) buoyage system.

A lighted buoy is a floating hull with a tower on whicha light is mounted. Batteries for the light are in watertightpockets in the buoy hull or in watertight boxes mounted onthe buoy hull. To keep the buoy in an upright position, acounterweight is attached to the hull below the water’ssurface. A radar reflector is built into the buoy tower.

The largest of the typical U.S. Coast Guard buoys canbe moored in up to 190 feet of water, limited by the weightof chain the hull can support. The focal plane of the light is

15 to 20 feet high. The designed nominal visual range is 3.8miles, and the radar range 4 miles. Actual conditions willcause these range figures to vary considerably.

The smallest buoys are designed for protected water.Some are made of plastic and weigh only 40 pounds.Specially designed buoys are used for fast current, ice, andother environmental conditions.

A variety of special purpose buoys are owned by othergovernmental organizations. Examples of these organi-zations include the St. Lawrence Seaway DevelopmentCorporation, NOAA, and the Department of Defense.These buoys are usually navigational marks or datacollection buoys with traditional round, boat-shaped, ordiscus-shaped hulls.

A special class of buoy, theOcean Data AcquisitionSystem (ODAS)buoy, is moored or floats free in offshore

waters. Positions are promulgated through radio warninThese buoys are generally not large enough to caudamage to a large vessel in a collision, but should be giva wide berth regardless, as any loss would almost certairesult in the interruption of valuable scientific experimentThey are generally bright orange or yellow in color, witvertical stripes on moored buoys and horizontal bandsfree-floating ones, and have a strobe light for nigvisibility.

Even in clear weather, the danger of collision withbuoy exists. If struck head-on, a large buoy can inflisevere damage to a large ship; it can sink a smaller oReduced visibility or heavy background lighting cacontribute to the problem of visibility. The Coast Guarsometimes receives reports of buoys missing from statthat were actually run down and sunk. Tugboats atowboats towing or pushing barges are particulardangerous to buoys because of poor over-the-bow visibilwhen pushing or yawing during towing. The professionmariner must reportanycollision with a buoy to the nearestCoast Guard unit. Failure to do so may cause the next vesto miss the channel or hit the obstruction marked by tbuoy; it can also lead to fines and legal liability.

Routine on-station buoy maintenance consistsinspecting the mooring, cleaning the hull ansuperstructure, replacing the batteries, flasher, and lamchecking wiring and venting systems, and verifying thbuoy’s exact position. Every few years, each buoyreplaced by a similar aid and returned to a Coast Guamaintenance facility for complete refurbishment.

The placement of a buoy depends on its purpose andposition on the chart. Most buoys are placed on their charpositions as accurately as conditions allow. However, if

Figure 509. Buoy showing counterweight.


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buoy’s purpose is to mark a shoal and the shoal is found to bein a different position than the chart shows, the buoy will beplaced to properly mark the shoal, and not on its chartedposition.

510. Lights on Buoys

Buoy light systems consist of abattery pack, aflasherwhich determines the characteristic, alamp changerwhichautomatically replaces burned-out bulbs, alensto focus thelight, and ahousing which supports the lens and protectsthe electrical equipment.

The batteries consist of 12-volt lead/acid typebatteries electrically connected to provide sufficient powerto run the proper flash characteristic and lamp size. Thesebattery packs are contained in pockets in the buoy hull,accessible through water-tight bolted hatches or externallymounted boxes. Careful calculations based on light charac-teristics determine how much battery power to install.

The flasher determines the characteristic of the lamp.It is installed in the housing supporting the lens.

The lamp changer consists of several socketsarranged around a central hub. A new lamp rotates intoposition if the active one burns out.

Under normal conditions, thelensesused on buoys are155mm in diameter at the base. 200 mm lenses are usedwhere breaking waves or swells call for the larger lens.They are colored according to the charted characteristic ofthe buoy. As in shore lights, the lamp must be carefullyfocused so that the filament is directly in line with the focalplane of the lens. This ensures that the majority of the lightproduced is focused in a 360° horizontal fan beam. A buoylight has a relatively narrow vertical profile. Because thebuoy rocks in the sea, the focal plane may only be visiblefor fractions of a second at great ranges. A realistic rangefor sighting buoy lights is 4-6 miles in good visibility andcalm weather.

511. Sound Signals on Buoys

Lighted sound buoys have the same general configu-ration as lighted buoys but are equipped with either a bell,gong, whistle, or horn.Bells and gongsare sounded bytappers hanging from the tower that swing as the buoy rocksin the sea. Bell buoys produce only one tone; gong buoysproduce several tones. The tone-producing device ismounted between the legs of the pillar or tower.

Whistle buoys make a loud moaning sound caused bythe rising and falling motions of the buoy in the sea. Asound buoy equipped with an electronichorn will producea pure tone at regular intervals regardless of the sea state.Unlighted sound buoys have the same general appearanceas lighted buoys, but their underwater shape is designed tomake them lively in all sea states.

512. Buoy Moorings

Buoys requiremoorings to hold them in position.Typically the mooring consists ofchain and a largeconcrete or cast ironsinker. See Figure 512. Because buoyare subjected to waves, wind, and tides, the moorings mbe deployed with chain lengths much greater than the wadepth. The scope of chain will normally be about 3 timethe water depth. The length of the mooring chain defineswatch circle within which the buoy can be expected toswing. It is for this reason that the charted buoy symbol ha “position approximate” circle to indicate its charteposition, whereas a light position is shown by a dot at thexact location. Actual watch circles do not necessarcoincide with the “position approximate” circles whichrepresent them.

Over several years, the chain gradually wears out amust be replaced. The worn chain is often cast into tconcrete of new sinkers.

513. Large Navigational Buoys

Large navigational buoysare moored in open waterat approaches to certain major seacoast ports and monitofrom shore stations by radio signals. These 40-fodiameter buoys (Figure 513) show lights from heightsabout 36 feet above the water. Emergency lights automically energize if the main light is extinguished. Thesbuoys may also have a radiobeacon and sound signals.

514. Wreck Buoys

A wreck buoy usually cannot be placed directly ovethe wreck it is intended to mark because the buoy tendmay not want to pass over a shallow wreck or risk foulinthe buoy mooring. For this reason, a wreck buoy is usua

Figure 512. A sinker used to anchor a buoy.


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placed as closely as possible on the seaward or channelwardside of a wreck. In some situations, two buoys may be usedto mark the wreck, one lying off each end. The wreck maylie directly between them or inshore of a line between them,depending on the local situation. TheLocal Notice toMariners should be consulted concerning details of theplacement of wreck buoys on individual wrecks. Often itwill also give particulars of the wreck and what activitiesmay be in progress to clear it.

The charted position of a wreck buoy will usually beoffset from the actual geographic position so that the wreckand buoy symbols do not coincide. Only on the largest scalechart will the actual and charted positions of both wreck andbuoy be the same. Where they might overlap, it is the wrecksymbol which occupies the exact charted position and thebuoy symbol which is offset.

Wreck buoys are required to be placed by the owner ofthe wreck, but they may be placed by the Coast Guard if theowner is unable to comply with this requirement. In general,privately placed aids are not as reliable as Coast Guard aids.

Sunken wrecks are sometimes moved away from thbuoys by storms, currents, freshets, or other causes. Jushoals may shift away from the buoys placed to mark thewrecks may shift away from wreck buoys.

515. Fallibility of Buoys

Buoys cannot be relied on to maintain their chartepositions consistently. They are subject to a varietyhazards including severe weather, collision, moorincasualties, and electrical failure. Mariners should repodiscrepancies to the authority responsible for maintainithe aid.

The buoy symbol shown on charts indicates thapproximate position of the sinker which secures the buto the seabed. The approximate position is used becauspractical limitations in keeping buoys in precisgeographical locations. These limitations includprevailing atmospheric and sea conditions, the slope atype of material making up the seabed, the scope of t

Figure 513. Large navigational buoy.


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mooring chain, and the fact that the positions of the buoysand the sinkers are not under continuous surveillance. Theposition of the buoy shifts around the area shown by thechart symbol due to the forces of wind and current.

A buoy may not be in its charted position because ofchanges in the feature it marks. For example, a buoy meant tomark a shoal whose boundaries are shifting might frequently bemoved to mark the shoal accurately. ALocal Notice to Marinerswill report the change, and aNotice to Marinerschart correction

may also be written. In some small channels which chanoften, buoys are not charted even when considered permanlocal knowledge is advised in such areas.

For these reasons, a mariner must not rely completupon the position or operation of buoys, but shounavigate using bearings of charted features, structures,aids to navigation on shore. Further, a vessel attemptingpass too close aboard a buoy risks a collision with the buor the obstruction it marks.

BUOYAGE SYSTEMS

516. Lateral and Cardinal Systems

There are two major types of buoyage systems: thelateral system and the cardinal system. The lateralsystem is best suited for well-defined channels. Thedescription of each buoy indicates the direction of dangerrelative to the course which is normally followed. Inprinciple, the positions of marks in the lateral system aredetermined by thegeneral direction taken by the marinerwhen approaching port from seaward. These positionsmay also be determined with reference to the main streamof flood current. The United States Aids to NavigationSystem is a lateral system.

The cardinal system is best suited for coasts withnumerous isolated rocks, shoals, and islands, and fordangers in the open sea. The characteristic of each buoyindicates the approximate true bearing of the danger itmarks. Thus, an eastern quadrant buoy marks a dangerwhich lies to the west of the buoy. The following pagesdiagram the cardinal and lateral buoyage systems as foundoutside the United States.

517. The IALA Maritime Buoyage System

Although most of the major maritime nations haveused either the lateral or the cardinal system for many years,details such as the buoy shapes and colors have varied fromcountry to country. With the increase in maritimecommerce between countries, the need for a uniformsystem of buoyage became apparent.

In 1889, an International Marine Conference held inWashington, D.C., recommended that in the lateral system,starboard hand buoys be painted red and port hand buoysblack. Unfortunately, when lights for buoys wereintroduced some years later, some European countriesplaced red lights on the black port hand buoys to conformwith the red lights marking the port side of harborentrances, while in North America red lights were placed onred starboard hand buoys. In 1936, a League of Nationssubcommittee recommended a coloring system opposite tothe 1889 proposal.

The International Association of LighthouseAuthorities (IALA) is a non-governmental organizationwhich consists of representatives of the worldwide

community of aids to navigation services. It promoteinformation exchange and recommends improvemebased on new technologies. In 1980, with the assistanceIMO and the IHO, the lighthouse authorities from 5countries and representatives of 9 international orgazations concerned with aids to navigation met and adopthe IALA Maritime Buoyage System. They establishedtwo regions,Region AandRegion B, for the entire world.Region A roughly corresponds to the 1936 LeagueNations system, and Region B to the older 1889 system

Lateral marks differ between Regions A and B. Latermarks in Region A use red and green colors by day and nito indicate port and starboard sides of channels, respectivIn Region B, these colors are reversed with red to starboand green to port. In both systems, the conventional directof buoyage is considered to be returning from sea, hencephrase “red right returning” in IALA region B.

518. Types of Marks

The IALA Maritime Buoyage System applies to allfixed and floating marks, other than lighthouses, sectlights, range lights, daymarks, lightships and large navigtional buoys, which indicate:

1. The side and center-lines of navigable channels2. Natural dangers, wrecks, and other obstructions3. Regulated navigation areas4. Other important features

Most lighted and unlighted beacons other than ranmarks are included in the system. In general, beactopmarks will have the same shape and colors as those uon buoys. The system provides five types of marks whimay be used in any combination:

1. Lateral marks indicate port and starboard sideschannels.

2. Cardinal marks, named according to the four poinof the compass, indicate that the navigable watlies to the named side of the mark.

3. Isolated danger marks erected on, or moordirectly on or over, dangers of limited extent.

4. Safe water marks, such as midchannel buoys.


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5. Special marks, the purpose of which is apparentfrom reference to the chart or other nauticaldocuments.

Characteristics of Marks

The significance of a mark depends on one or morefeatures:

1. By day—color, shape, and topmark2. By night—light color and phase characteristics

Colors of Marks

The colors red and green are reserved for lateral marks,and yellow for special marks. The other types of markshave black and yellow or black and red horizontal bands, orred and white vertical stripes.

Shapes of Marks

There are five basic buoy shapes:1. Can2. Cone3. Sphere4. Pillar5. Spar

In the case of can, conical, and spherical, the shapeshave lateral significance because the shape indicates thecorrect side to pass. With pillar and spar buoys, the shapehas no special significance.

The term “pillar” is used to describe any buoy which issmaller than a large navigation buoy (LNB) and which has atall, central structure on a broad base; it includes beaconbuoys, high focal plane buoys, and others (except spar buoys)whose body shape does not indicate the correct side to pass.

Topmarks

The IALA System makes use ofcan, conical,spherical, and X-shaped topmarks only. Topmarks onpillar and spar buoys are particularly important and will beused wherever practicable, but ice or other severeconditions may occasionally prevent their use.

Colors of Lights

Where marks are lighted, red and green lights arereserved for lateral marks, and yellow for special marks.The other types of marks have a white light, distinguishedone from another by phase characteristic.

Phase Characteristics of Lights

Red and green lights may have any phase charac-

teristic, as the color alone is sufficient to show on whicside they should be passed. Special marks, when lighthave a yellow light with any phase characteristic nreserved for white lights of the system. The other typesmarks have clearly specified phase characteristics of whlight: various quick-flashing phase characteristics focardinal marks, group flashing (2) for isolated dangmarks, and relatively long periods of light for safe watemarks.

Some shore lights specifically excluded from the IALASystem may coincidentally have characteristiccorresponding to those approved for use with the nemarks. Care is needed to ensure that such lights aremisinterpreted.

519. IALA Lateral Marks

Lateral marks are generally used for well-definedchannels; they indicate the port and starboard hand sidethe route to be followed, and are used in conjunction withconventional direction of buoyage.

This direction is defined in one of two ways:

1. Local direction of buoyage is the direction takenby the mariner when approaching a harbor, rivestuary, or other waterway from seaward.

2. General direction of buoyage is determined bythe buoyage authorities, following a clockwisdirection around continental land-masses, givensailing directions, and, if necessary, indicated ocharts by a large open arrow symbol.

In some places, particularly straits open at both endthe local direction of buoyage may be overridden by thgeneral direction.

Along the coasts of the United States, the charactistics assume that proceeding “from seaward” constituteclockwise direction: a southerly direction along the Atlantcoast, a westerly direction along the Gulf of Mexico coasand a northerly direction along the Pacific coast. On tGreat Lakes, a westerly and northerly direction is takenbeing “from seaward” (except on Lake Michigan, wheresoutherly direction is used). On the Mississippi and OhRivers and their tributaries, the characteristics of aidsnavigation are determined as proceeding from sea towthe head of navigation. On the Intracoastal Waterwaproceeding in a generally southerly direction along thAtlantic coast, and in a generally westerly direction alonthe gulf coast, is considered as proceeding “from seawar

520. IALA Cardinal Marks

A cardinal mark is used in conjunction with thecompass to indicate where the mariner may find the bnavigable water. It is placed in one of the four quadran(north, east, south, and west), bounded by the true beari


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NW-NE, NE-SE, SE-SW, and SW-NW, taken from thepoint of interest. A cardinal mark takes its name from thequadrantin which it is placed.

The mariner is safe if he passes north of a north mark, eastof an east mark, south of a south mark, and west of a west mark.

A cardinal mark may be used to:

1. Indicate that the deepest water in an area is on thenamed side of the mark.

2. Indicate the safe side on which to pass a danger.3. Emphasize a feature in a channel, such as a bend,

junction, bifurcation, or end of a shoal.

Topmarks

Black double-cone topmarks are the most importantfeature, by day, of cardinal marks. The cones are verticallyplaced, one over the other. The arrangement of the cones isvery logical: North is two cones with their points up (as in“north-up”). South is two cones, points down. East is twocones with bases together, and west is two cones withpoints together, which gives a wineglass shape. “West is aWineglass” is a memory aid.

Cardinal marks carry topmarks whenever practicable,with the cones as large as possible and clearly separated.

Colors

Black and yellow horizontal bands are used to color acardinal mark. The position of the black band, or bands, isrelated to the points of the black topmarks.

Shape

The shape of a cardinal mark is not significant, butbuoys must be pillars or spars.

Lights

When lighted, a cardinal mark exhibits a white light; itscharacteristics are based on a group of quick or very quickflashes which distinguish it as a cardinal mark and indicate itsquadrant. The distinguishing quick or very quick flashes are:

North—UninterruptedEast—three flashes in a groupSouth—six flashes in a group followed by a long flashWest—nine flashes in a group

As a memory aid, the number of flashes in each grocan be associated with a clock face: 3 o’clock—E,o’clock—S, and 9 o’clock—W.

The long flash (of not less than 2 seconds durationimmediately following the group of flashes of a south cadinal mark, is to ensure that its six flashes cannotmistaken for three or nine.

The periods of the east, south, and west lights are,spectively, 10, 15, and 15 seconds if quick flashing; and10, and 10 seconds if very quick flashing.

Quick flashing lights flash at a rate between 50 and 7flashes per minute, usually either 50 or 60. Very quicflashing lights flash at a rate between 80 and 159 flashesminute, usually either 100 or 120.

It is necessary to have a choice of quick flashingvery quick flashing lights in order to avoid confusion if, foexample, two north buoys are placed near enough to eother for one to be mistaken for the other.

521. IALA Isolated Danger Marks

An isolated danger mark is erected on, or moored onor above, an isolated danger of limited extent which hnavigable water all around it. The extent of the surroundinnavigable water is immaterial; such a mark can, foexample, indicate either a shoal which is well offshore or aislet separated by a narrow channel from the coast.

Position

On a chart, the position of a danger is the center of tsymbol or sounding indicating that danger; an isolatedanger buoy may therefore be slightly displaced fromgeographic position to avoid overprinting the two symbolThe smaller the scale, the greater this offset will be. At velarge scales the symbol may be correctly charted.

Topmark

A black double-sphere topmark is, by day, the moimportant feature of an isolated danger mark. Whenevpracticable, this topmark will be carried with the sphereslarge as possible, disposed vertically, and clearly separate

Color

Black with one or more red horizontal bands are thcolors used for isolated danger marks.

Shape

The shape of an isolated danger mark is not significabut a buoy will be a pillar or a spar.

N Points up Black above yellowS Points down Black below yellowW Points together Black, yellow above and belowE Points apart Yellow, black above and below


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Light

When lighted, a white flashing light showing a groupof two flashes is used to denote an isolated danger mark. Asa memory aid, associate two flashes with two balls in thetopmark.

522. IALA Safe Water Marks

A safe water mark is used to indicate that there isnavigable water all around the mark. Such a mark may beused as a center line, mid-channel, or landfall buoy.

Color

Red and white vertical stripes are used for safe watermarks, and distinguish them from the black-banded,danger-marking marks.

Shape

Spherical, pillar, or spar buoys may be used as safe watermarks.

Topmark

A single red spherical topmark will be carried,whenever practicable, by a pillar or spar buoy used as a safewater mark.

Lights

When lighted, safe water marks exhibit a white light.This light can be occulting, isophase, a single long flash, orMorse “A.” If a long flash (i.e. a flash of not less than 2seconds) is used, the period of the light will be 10 seconds.As a memory aid, remember a single flash and a singlesphere topmark.

523. IALA Special Marks

A special markmay be used to indicate a special areaor feature which is apparent by referring to a chart, sailingdirections, or notices to mariners. Uses include:

1. Ocean Data Acquisition System (ODAS) buoys2. Traffic separation marks3. Spoil ground marks4. Military exercise zone marks5. Cable or pipeline marks, including outfall pipes6. Recreation zone marks

Another function of a special mark is to define a channelwithin a channel. For example, a channel for deep draft vesselsin a wide estuary, where the limits of the channel for normal

navigation are marked by red and green lateral buoys, mhave its boundaries or centerline marked by yellow buoysthe appropriate lateral shapes.

Color

Yellow is the color used for special marks.

Shape

The shape of a special mark is optional, but must nconflict with that used for a lateral or a safe water mark. Fexample, an outfall buoy on the port hand side of a chancould be can-shaped but not conical.

Topmark

When a topmark is carried it takes the form of a singyellow X.

Lights

When a light is exhibited it is yellow. It may show anyphase characteristic except those used for the white lightcardinal, isolated danger, and safe water marks. In the cof ODAS buoys, the phase characteristic used is grouflashing with a group of five flashes every 20 seconds.

524. IALA New Dangers

A newly discovered hazard to navigation not yet showon charts, included in sailing directions, or announced byNotice to Marinersis termed anew danger. The term coversnaturally occurring and man-made obstructions.

Marking

A new danger is marked by one or more cardinallateral marks in accordance with the IALA system rules.the danger is especially grave, at least one of the marks wbe duplicated as soon as practicable by an identical muntil the danger has been sufficiently identified.

Lights

If a lighted mark is used for a new danger, it musexhibit a quick flashing or very quick flashing light. If acardinal mark is used, it must exhibit a white light; if alateral mark, a red or green light.

Racons

The duplicate mark may carry a Racon, Morse codedshowing a signal length of 1 nautical mile on a radar displa


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525. Chart Symbols and Abbreviations

Spar buoys and spindle buoys are represented by the samesymbol; it is slanted to distinguish them from upright beaconsymbols. The abbreviated description of the color of a buoy isgiven under the symbol. Where a buoy is colored in bands, thecolors are indicated in sequence from the top. If the sequence ofthe bands is not known, or if the buoy is striped, the colors areindicated with the darker color first.

Topmarks

Topmark symbols are solid black except if the topmarkis red.

Lights

The period of the light of a cardinal mark is determinedby its quadrant and its flash characteristic (either quick-flashing or a very quick-flashing). The light’s period is lessimportant than its phase characteristic. Where space oncharts is limited, the period may be omitted.

Light Flares

Magenta light-flares are normally slanted and inserted withtheir points adjacent to the position circles at the base of thesymbols so the flare symbols do not obscure the topmarksymbols.

Radar Reflectors

According to IALA rules, radar reflectors are notcharted, for several reasons. First, all important buoys arefitted with radar reflectors. It is also necessary to reduce thesize and complexity of buoy symbols and associatedlegends. Finally, it is understood that, in the case of cardinalbuoys, buoyage authorities place the reflector so that itcannot be mistaken for a topmark.

The symbols and abbreviations of the IALA MaritimeBuoyage System may be found inU.S. Chart No. 1and inforeign equivalents.

526. Description of the U.S. Aids to Navigation System

In the United States, the U.S. Coast Guard hasincorporated the major features of the IALA system with theexisting infrastructure of buoys and lights as explainedbelow.

Colors

Under this system, green buoys mark a channel’s portside and obstructions which must be passed by keeping thebuoy on the port hand. Red buoys mark a channel’sstarboard side and obstructions which must be passed by

keeping the buoy on the starboard hand.Red and green horizontally bandedpreferred channel

buoys mark junctions or bifurcations in a channel oobstructions which may be passed on either side. If ttopmost band is green, the preferred channel will bfollowed by keeping the buoy on the port hand. If thtopmost band is red, the preferred channel will be followeby keeping the buoy on the starboard hand.

Red and white vertically striped safe water buoys maa fairway or mid-channel.

Reflective material is placed on buoys to assist in thedetection at night with a searchlight. The color of the reflectimaterial agrees with the buoy color. Red or green reflectmaterial may be placed on preferred channel (junction) buored if topmost band is red, or green if the topmost band is greWhite reflective material is used on safe water buoys. Spepurpose buoys display yellow reflective material. Warningregulatory buoys display orange reflective horizontal bands aa warning symbol. Intracoastal Waterway buoys displayyellow reflective square, triangle, or horizontal strip along withe reflective material coincident with the buoy’s function.

Shapes

Certain unlighted buoys are differentiated by shape. Rbuoys and red and green horizontally banded buoys withtopmost band red are cone-shaped buoys callednuns. Greenbuoys and green and red horizontally banded buoys withtopmost band green are cylinder-shaped buoys calledcans.

Unlighted red and white vertically striped buoys may bpillar shaped or spherical. Lighted buoys, sound buoys, and sbuoys are not differentiated by shape to indicate the sidewhich they should be passed. Their purpose is indicated noshape but by the color, number, or light characteristics.

Numbers

All solid colored buoys are numbered, red buoybearing even numbers and green buoys bearing onumbers. (Note that this same rule applies in IALA SysteA also.) The numbers increase from seaward upstreamtoward land. No other colored buoys are numberehowever, any buoy may have a letter for identification.

Light Colors

Red lights are used only on red buoys or red and grehorizontally banded buoys with the topmost band red. Grelights are used only on the green buoys or green andhorizontally banded buoys with the topmost band green. Whlights are used on both “safe water” aids showing a Morse Co“A” characteristic and on Information and Regulatory aids.

Light Characteristics

Lights on red buoys or green buoys, if not occultin


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or isophase, will generally be regularly flashing (Fl). Forordinary purposes, the frequency of flashes will be notmore than 50 flashes per minute. Lights with a distinctcautionary significance, such as at sharp turns ormarking dangerous obstructions, will flash not less than50 flashes but not more than 80 flashes per minute (quickflashing, Q). Lights on preferred channel buoys willshow a series of group flashes with successive groups ina period having a different number of flashes - compositegroup flashing (or a quick light in which the sequence offlashes is interrupted by regularly repeated eclipses ofconstant and long duration). Lights on safe water buoyswill always show a white Morse Code “A” (Short-Long)flash recurring at the rate of approximately eight timesper minute.

Daylight Controls

Lighted buoys have a special device to energize tlight when darkness falls and to de-energize the light whday breaks. These devices are not of equal sensitivtherefore all lights do not come on or go off at the samtime. Mariners should ensure correct identification of aidduring twilight periods when some light aids to navigatioare on while others are not.

Special Purpose Buoys

Buoys for special purposes are colored yellow. Whibuoys with orange bands are for informational or regulatopurposes. The shape of special purpose buoys has no sigicance. They are not numbered, but they may be letteredlighted, special purpose buoys display a yellow lighusually with fixed or slow flash characteristics. Informatioand regulatory buoys, if lighted, display white lights.

BEACONS

527. Definition and Description

Beaconsare fixed aids to navigation placed on shoreor on pilings in relatively shallow water. If unlighted, thebeacon is referred to as adaybeacon. A daybeacon isidentified by the color, shape, and number of itsdayboard. The simplest form of daybeacon consists of asingle pile with a dayboard affixed at or near its top. SeeFigure 527. Daybeacons may be used to form an unlightedrange.. Dayboards identify aids to navigation against daylightbackgrounds. The size of the dayboard required to make theaid conspicuous depends upon the aid’s intended range.

Most dayboards also display numbers or letters for identi-fication. The numbers, letters, and borders of most dayboardshave reflective tape to make them visible at night.

The detection, recognition, and identification distancesvary widely for any particular dayboard. They depend uponthe luminance of the dayboard, the Sun’s position, and thelocal visibility conditions.

SOUND SIGNALS

528. Types of Sound Signals

Most lighthouses and offshore light platforms, as wellas some minor light structures and buoys, are equipped withsound-producing devices to help the mariner in periods oflow visibility. Charts and Light Lists contain theinformation required for positive identification. Buoysfitted with bells, gongs, or whistles actuated by wavemotion may produce no sound when the sea is calm. Soundsignals are not designed to identify the buoy or beacon fornavigation purposes. Rather, they allow the mariner to passclear of the buoy or beacon during low visibility.

Sound signals vary. The navigator must use the

Light List to determine the exact length of each blast ansilent interval. The various types of sound signals aldiffer in tone, facilitating recognition of the respectivestations.

Diaphonesproduce sound with a slotted piston moveback and forth by compressed air. Blasts may consist ohigh and low tone. These alternate-pitch signals are cal“two-tone.” Diaphones are not used by the Coast Guard, bthe mariner may find them on some private navigation aid

Horns produce sound by means of a disc diaphragoperated pneumatically or electrically. Duplex or triplehorn units of differing pitch produce a chime signal.

Sirens produce sound with either a disc or a cup

Figure 527. Daybeacon.


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Whistles use compressed air emitted through acircumferential slot into a cylindrical bell chamber.

Bells and gongs are sounded with a mechanicallyoperated hammer.

529. Limitations of Sound Signals

As aids to navigation, sound signals have seriouslimitations because sound travels through the air in anunpredictable manner.

It has been clearly established that:

1. Sound signals are heard at greatly varyingdistances and that the distance at which a soundsignal can be heard may vary with the bearing andtiming of the signal.

2. Under certain atmospheric conditions, when asound signal has a combination high and low tone,it is not unusual for one of the tones to be inaudible.In the case of sirens, which produce a varying tone,portions of the signal may not be heard.

3. When the sound is screened by an obstruction,there are areas where it is inaudible.

4. Operators may not activate a remotely controlledsound aid for a condition unobserved from thecontrolling station.

5. Some sound signals cannot be immediately started.6. The status of the vessel’s engines and the location

of the observer both affect the effective range of theaid.

These considerations justify the utmost caution whenavigating near land in a fog. A navigator can never reon sound signals alone; he should continuously man bothe radar and fathometer. He should place lookoutspositions where the noises in the ship are least likelyinterfere with hearing a sound signal. The aid upon whica sound signal rests is usually a good radar target,collision with the aid or the danger it marks is alwayspossibility.

Emergency signals are sounded at some of the light afog signal stations when the main and stand-by sousignals are inoperative. Some of these emergency sosignals are of a different type and characteristic than tmain sound signal. The characteristics of the emergensound signals are listed in theLight List.

The mariner should never assume:

1. That he is out of ordinary hearing distance becauhe fails to hear the sound signal.

2. That because he hears a sound signal faintly, hefar from it.

3. That because he hears it clearly, he is near it.

4. That the distance from and the intensity of a sounon any one occasion is a guide for any futuroccasion.

5. That the sound signal is not sounding becausedoes not hear it, even when in close proximity.

6. That the sound signal is in the direction the sounappears to come from.

MISCELLANEOUS U.S. SYSTEMS

530. Intracoastal Waterway Aids to Navigation

The Intracoastal Waterway (ICW) runs parallel to theAtlantic and Gulf of Mexico coasts from Manasquan Inlet onthe New Jersey shore to the Texas/Mexican border. It followsrivers, sloughs, estuaries, tidal channels, and other naturalwaterways, connected with dredged channels wherenecessary. Some of the aids marking these waters are markedwith yellow; otherwise, the marking of buoys and beaconsfollows the same system as that in other U.S. waterways.

Yellow symbols indicate that an aid marks the Intrac-oastal Waterway. Yellow triangles indicate starboard handaids, and yellow squares indicate port hand aids whenfollowing the ICW’s conventional direction of buoyage.Non-lateral aids such as safe water, isolated danger, andfront range boards are marked with a horizontal yellowband. Rear range boards do not display the yellow band. Ata junction with a federally-maintained waterway, thepreferred channel mark will display a yellow triangle orsquare as appropriate. Junctions between the ICW andprivately maintained waterways are not marked with

preferred channel buoys.

531. Western Rivers System

Aids to navigation on the Mississippi River and ittributaries above Baton Rouge generally conform to tlateral system of buoyage in use in the rest of the U.S. Tfollowing differences are significant:

1. Buoys are not numbered.

2. The numbers on lights and daybeacons do not halateral significance; they indicate the mileage froma designated point, normally the river mouth.

3. Flashing lights on the left side proceeding upstreashow single green or white flashes while those othe right side show group flashing red or whitflashes.

4. Diamond shaped crossing daymarks are usedindicate where the channel crosses from one sidethe river to the other.


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532. The Uniform State Waterway Marking System(USWMS)

This system was developed jointly by the U.S. CoastGuard and state boating administrators to assist the smallcraft operator in those state waters marked by participatingstates. TheUSWMS consists of two categories of aids tonavigation. The first is a system of aids to navigation,generally compatible with the Federal lateral system ofbuoyage, supplementing the federal system in state waters.The other is a system of regulatory markers to warn smallcraft operators of dangers or to provide generalinformation.

On a well-defined channel, red and black buoys areestablished in pairs calledgates; the channel lies between thebuoys. The buoy which marks the left side of the channelviewed looking upstream or toward the head of navigation isblack; the buoy which marks the right side of the channel isred.

In an irregularly-defined channel, buoys may bestaggered on alternate sides of the channel, but they arespaced at sufficiently close intervals to mark clearly thechannel lying between them.

Where there is no well-defined channel or where abody of water is obstructed by objects whose nature orlocation is such that the obstruction can be approached by avessel from more than one direction, aids to navigationhaving cardinal significance may be used. The aidsconforming to the cardinal system consist of three distinctlycolored buoys as follows:

1. A white buoy with a red top must be passed to thesouth or west of the buoy.

2. A white buoy with a black top must be passed to thenorth or east of the buoy.

3. A buoy showing alternate vertical red and whitestripes indicates that an obstruction to navigationextends from the nearest shore to the buoy and thatthe vessel must not pass between the buoy and thenearest shore.

The shape of buoys has no significance under theUSWMS.

Regulatory buoys are colored white with orangehorizontal bands completely around them. One band is atthe top of the buoy and a second band just above thewaterline of the buoy so that both orange bands areclearly visible.

Geometric shapes colored orange are placed on thewhite portion of the buoy body. The authorized geometricshapes and meanings associated with them are as follows:

1. A vertical open faced diamond shape meansdanger.

2. A vertical open faced diamond shape with a cross

centered in the diamond means that vesselsexcluded from the marked area.

3. A circular shape means that vessels in the markarea are subject to certain operating restrictions.

4. A square or rectangular shape indicates thdirections or information is written inside theshape.

Regulatory markers consist of square and rectangushaped signs displayed from fixed structures. Each signwhite with an orange border. Geometric shapes with tsame meanings as those displayed on buoys are centerethe sign boards. The geometric shape displayed onregulatory marker tells the mariner if he should stay weclear of the marker or if he may approach the markerorder to read directions.

533. Private Aids to Navigation

A private navigation aid is any aid established andmaintained by entities other than the Coast Guard.

The Coast Guard must approve the placementprivate navigation aids. In addition, the District EngineeU.S. Army Corps of Engineers, must approve thplacement of any structure, including aids to navigation,the navigable waters of the U.S.

Private aids to navigation are similar to the aidestablished and maintained by the U.S. Coast Guard; thare specially designated on the chart and in theLight List.In some cases, particularly on large commercial structurthe aids are the same type of equipment used by the CoGuard. Although the Coast Guard periodically inspecsome private navigation aids, the mariner should exercspecial caution when using them.

In addition to private aids to navigation, numeroutypes of construction and anchor buoys are used in variooil drilling operations and marine construction. Thesbuoys are not charted, as they are temporary, and maybe lighted well or at all. Mariners should give a wide bertto drilling and construction sites to avoid the possibility ofouling moorings. This is a particular danger in offshoroil fields, where large anchors are often used to stabilithe positions of drill rigs in deep water. Up to eighanchors may be placed at various positions as much amile from the drill ship. These positions may or may nobe marked by buoys. Such operations in the U.S. aannounced in theLocal Notice to Mariners.

534. Protection by Law

It is unlawful to impair the usefulness of anynavigation aid established and maintained by the UnitStates. If any vessel collides with a navigation aid, it is thlegal duty of the person in charge of the vessel to report taccident to the nearest U.S. Coast Guard station.

chapter 5 short range aids to navigation

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