68SHORTRANGEAIDS TONAVIGATIONTypeDesariptionustralxanAttrevation4.2Group-flashing.FI (2)日Aflashinglightinwhichagroupof flashes,specified in number,isregularly,petod,repeated.4.3 Compositegroup-flashingAlightsimilarto agroupflashing lightexceptthat successivegroups intheperiodFI(2+perfod.havedifferentnumbersofflashes.5.QUICK.A light in which flashes are produced at a raleof 60 fiashes perminute5.1ContinuousquickaAquick light in which a flash is regularly repeated.IQ5.2InterruptedquickA quick light in which the sequence of flashes is interrupted by regularly repeatededipsesofconstantandlongduration.6.MORSECODEMo(AAlight in whichappearances of lightoftwoclearlydifferentdurations (dotsandperioddashes) are grouped to represent a characteror characters in the Morse codeFFI7.FIXEDANDFLASHING.Alight in which a fixed light is combined with a flashing light of higherluminousperiod,intensity.AIRM8.ALTERNATINGAlightshowingdifferentcolorsallemalelyperioe,Figure506b.Lightphasecharacteristics
68 SHORT RANGE AIDS TO NAVIGATION Figure 506b. Light phase characteristics
69SHORTRANGEAIDS TONAVIGATIONregular flashes. This is due to reflections of a rotating lensalternating flashing white and red (F W AI WR).This is be-on panes of glass in the lighthousecause for a given candlepower, white is the most visibleIf a light is not sighted within a reasonable time aftercolor,green less so,and red leastofthethree.Thisfactalsoprediction,adangerous situation may exist.Conversely,theaccounts for the differentrangesgiven in the Light Lists forlightmay simply be obscured or extinguished.The ship'ssome multi-color sector lights.Thesame lamphas differentposition should immediatelybefixedby othermeanstode-ranges according to the color imparted by the sector glasstermine any possibility of danger.A light may be extinguished due to weather,batteryThe apparent characteristic of a complex light mayfailure,vandalism,or other causes.In the case of unattend-changewith thedistance of the observer.For example,aed lights,this condition might not beimmediatelylight with a characteristic of fixed white and alternatingcorrected.Themariner should report this condition to theflashing whiteand redmayinitially showas a simpleflash-nearest Coast Guard station.During periods of armed con-ing white light. As the vessel draws nearer, the red flashflict, certain lights may be deliberately extinguishedwill become visible and the characteristic willapparentlybewithout notice.alternating flashing white and red. Later, the fainter fixedOffshorelight stations should alwaysbeleft well offwhite light will be seen between the flashes and the truecharacteristicofthelightfinallyrecognizedasfixedwhite,the course whenever searoom permits.BUOYS509.Definitions And TypesBuoys arefloating aids to navigation.Theymarkchannels, indicate shoals and obstructions,and warn the marinerof dangers.Buoys are used where fixed aids would be un-economicalorimpracticalduetothedepthofwater.Bytheir color,shape,topmark,number,and light characteris-tics,buoys indicatetothemariner howtoavoid hazards andstay in safe water.The federal buoyage system in the U.S.ismaintainedbytheCoastGuard.Therearemanydifferent sizes and types of buoys de-signedto meeta widerangeofenvironmental conditionsand user requirements.The size ofabuoy is determined primarily by its location.In general, the smallest buoy whichwill stand up to local weather and current conditions ischosen.There are five types of buoys maintained by the CoastGuard. They are:1.Lateral marks.Figure 509.Buoy showing counterweight.2.Isolated danger marks.3.Safewatermarks.15to20feethigh.The designed nominal visual range is3.84.Specialmarks.miles, and the radar range 4 miles. Actual conditions will5.Information/regulatorymarks.cause these range figures to vary considerably.The smallest buoys are designed for protected waterTheseconform ingeneral tothe specifications of theSomearemadeof plastic and weighonly40pounds.SpeInternational Association of Lighthouse Authoritiescially designed buoys are used for fast current, ice, and(IALA) buoyage system.otherenvironmental conditions.Alighted buoyis a floating hull with atower on whichAvariety of special purpose buoys are owned by othera light is mounted.Batteries for the light are in watertightgovermmental organizations.Examplesof theseorganiza-pockets in the buoyhull or in watertight boxesmounted ontions include the Panama Canal Commission,the Stthe buoy hull.To keep the buoy in an upright position, aLawrenceSeawayDevelopmentCorporation,NOAA,andcounterweight is attached to the hull below the water sur-the Department of Defense.These buoys are usually navi-face.A radar reflector is built into the buoy tower.gational marks or data collection buoys with traditionalThelargest ofthetypicalU.S.CoastGuard buoys canround, boat-shaped, or discus-shaped hulls.bemoored in upto190feetofwater,limited by the weightof chain the hull can support. The focal plane ofthe light isA special class of buoy,theOceanDataAcquisition
SHORT RANGE AIDS TO NAVIGATION 69 regular flashes. This is due to reflections of a rotating lens on panes of glass in the lighthouse. If a light is not sighted within a reasonable time after prediction, a dangerous situation may exist. Conversely, the light may simply be obscured or extinguished. The ship’s position should immediately be fixed by other means to determine any possibility of danger. The apparent characteristic of a complex light may change with the distance of the observer. For example, a light with a characteristic of fixed white and alternating flashing white and red may initially show as a simple flashing white light. As the vessel draws nearer, the red flash will become visible and the characteristic will apparently be alternating flashing white and red. Later, the fainter fixed white light will be seen between the flashes and the true characteristic of the light finally recognized as fixed white, alternating flashing white and red (F W Al W R). This is because for a given candlepower, white is the most visible color, green less so, and red least of the three. This fact also accounts for the different ranges given in the Light Lists for some multi-color sector lights. The same lamp has different ranges according to the color imparted by the sector glass. A light may be extinguished due to weather, battery failure, vandalism, or other causes. In the case of unattended lights, this condition might not be immediately corrected. The mariner should report this condition to the nearest Coast Guard station. During periods of armed conflict, certain lights may be deliberately extinguished without notice. Offshore light stations should always be left well off the course whenever searoom permits. BUOYS 509. Definitions And Types Buoys are floating aids to navigation. They mark channels, indicate shoals and obstructions, and warn the mariner of dangers. Buoys are used where fixed aids would be uneconomical or impractical due to the depth of water. By their color, shape, topmark, number, and light characteristics, buoys indicate to the mariner how to avoid hazards and stay in safe water. The federal buoyage system in the U.S. is maintained by the Coast Guard. There are many different sizes and types of buoys designed to meet a wide range of environmental conditions and user requirements. The size of a buoy is determined primarily by its location. In general, the smallest buoy which will stand up to local weather and current conditions is chosen. There are five types of buoys maintained by the Coast Guard. They are: 1. Lateral marks. 2. Isolated danger marks. 3. Safe water marks. 4. Special marks. 5. Information/regulatory marks. These conform in general to the specifications of the International Association of Lighthouse Authorities (IALA) buoyage system. A lighted buoy is a floating hull with a tower on which a light is mounted. Batteries for the light are in watertight pockets in the buoy hull or in watertight boxes mounted on the buoy hull. To keep the buoy in an upright position, a counterweight is attached to the hull below the water surface. A radar reflector is built into the buoy tower. The largest of the typical U.S. Coast Guard buoys can be moored in up to 190 feet of water, limited by the weight of chain the hull can support. The focal plane of the light is 15 to 20 feet high. The designed nominal visual range is 3.8 miles, and the radar range 4 miles. Actual conditions will cause 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, and other environmental conditions. A variety of special purpose buoys are owned by other governmental organizations. Examples of these organizations include the Panama Canal Commission, the St. Lawrence Seaway Development Corporation, NOAA, and the Department of Defense. These buoys are usually navigational marks or data collection buoys with traditional round, boat-shaped, or discus-shaped hulls. A special class of buoy, the Ocean Data Acquisition Figure 509. Buoy showing counterweight