Aids to navigation
Ai
Aids ds to to nanavivigagatitionon are are spspeciecial al strstructuctureures s liklike e liglighththouhousesses, , liglightshtshiphips,s,
bea
beaconcons, s, bubuoysoys, , etc etc thathat t are are usused ed to to enhenhanance ce safsafety ety by by proprovidviding ing mormoree opportunities to obtain LOPs.
opportunities to obtain LOPs.
These lights and marks are prescribed across the world by the International These lights and marks are prescribed across the world by the International Association of Lighthouse Authorities (IALA). In 1977
Association of Lighthouse Authorities (IALA). In 1977 thisthis IALAIALA endorsed twoendorsed two
maritime buoyage systems putting an end to the 30 odd systems existing at maritime buoyage systems putting an end to the 30 odd systems existing at that time. Region A -
that time. Region A - IALA AIALA A covers all of Europe and most of the rest of covers all of Europe and most of the rest of thethe world, whereas region B -
world, whereas region B - IALA BIALA B covers only the Americas, Japan, thecovers only the Americas, Japan, the Phi
Philiplippinpines es and and KorKorea. ea. ForFortuntunateately, ly, ththe e difdifferferencences es betbetweeween n ththese ese twtwoo systems are few. The most striking difference is the
systems are few. The most striking difference is the direction of buoyagedirection of buoyage..
All marks within the IALA system are distinguished by: All marks within the IALA system are distinguished by: Shape Shape Colour Colour Topmark Topmark Light Light
Light identification
Light identification
During daytime, the identification of aids to navigation is accomplished by During daytime, the identification of aids to navigation is accomplished by observing:
observing: locationlocation,, shapeshape,, colour schemecolour scheme,, auxiliary featuresauxiliary features (sound(sound ssiiggnnaallss, , RRAACCOONN , R, RCC , , eettcc) ) oorr markingsmarkings (name, number, etc).(name, number, etc).
During the night, we use the features of the aid to navigation's
During the night, we use the features of the aid to navigation's lightlight to bothto both identify it and ascertain its purpose. There are three features to describe the identify it and ascertain its purpose. There are three features to describe the light:
light: Colour
Colour: Either white, red, green or yellow. : Either white, red, green or yellow. If no colour is stated in the If no colour is stated in the chart,chart, default is white.
default is white. Period
Period: The time in seconds needed for one complete cycle of changes.: The time in seconds needed for one complete cycle of changes. Th
The e ararrow row inindidicacatetes s ththe e 10 10 sesecocond nd pepeririod od of of ththisis flashing light “Fl(3) 10s”.
flashing light “Fl(3) 10s”. Phase
Phase charactcharacteristeristicic: : ThThe e papartrticiculular ar papatttterern n of of chchanangeges s wiwiththin in ononee complete cycle (hence, within one period). Below are the most common complete cycle (hence, within one period). Below are the most common types:
Fixed
Fixed FF
This light shines with an unblinking and steady This light shines with an unblinking and steady intensity and is always on. In this example a yellow fixed light is intensity and is always on. In this example a yellow fixed light is shown.
shown. Flashing
Flashing FlFl::
The duration of the light is always less than the The duration of the light is always less than the duration of the darkness. The frequency does not exceed 30 times per duration of the darkness. The frequency does not exceed 30 times per minute.
minute.
Quick Flashing
Quick Flashing QQ::
Again, the duration of quick flash is less than Again, the duration of quick flash is less than the darkness. The frequency is at least 60
the darkness. The frequency is at least 60 times per minute.times per minute. Very Quick Flashing
Very Quick Flashing VQVQ::
Also here, the duration of very quick flash is less Also here, the duration of very quick flash is less than the darkness. The frequency is at least 100 times per
than the darkness. The frequency is at least 100 times per minute.minute. Interrupted Quick Flashing
Interrupted Quick Flashing IQ::IQ L
Liikke e QQuuiicck k FFllaasshhiinng g wwitith h oonne e mmoommeennt t oof f darkness in one period.
darkness in one period. Isophase
Isophase IsoIso::
This Light has equal duration between light and This Light has equal duration between light and darkness. A period consists of both a light and a dark interval. Also darkness. A period consists of both a light and a dark interval. Also called Equal Interval (E Int).
called Equal Interval (E Int). Group Flashing
Group Flashing Gp Fl(x+x)Gp Fl(x+x)::
This is actually a combination of two patterns in This is actually a combination of two patterns in one period. In this example the first 2 flashes followed by the pattern one period. In this example the first 2 flashes followed by the pattern of 3 flashes result in:
of 3 flashes result in: Gp Fl(2+3).Gp Fl(2+3). Occulting
Occulting OccOcc::
Occulting is the opposite of flashing, the light is Occulting is the opposite of flashing, the light is more on then off.
more on then off. Alternating
Alternating ALAL::
An alternating light changes colour. This special An alternating light changes colour. This special purpose light is typically used for special applications requiring the purpose light is typically used for special applications requiring the ex
exerercicisse e of of ggrereaat t ccaauuttioion. n. In In tthhis is exexamampple le ALALT.T.WWG G is is sshohowwnn,, alternating between green and white.
alternating between green and white. Morse U
Morse U Mo (U)::Mo (U)
Th
This is liglight ht shshows ows twtwo o flaflashshes es anand d a a lonlongfgflaslash,h, which is equivalent to the letter “U” in Morse code.
which is equivalent to the letter “U” in Morse code. Long-Flashing
Long-Flashing LFlLFl::
This light has one long flash in a period. A long This light has one long flash in a period. A long flash is at least 2
Let's look at some examples using colour, period and phase characteristics. Let's look at some examples using colour, period and phase characteristics. The arrows mark the periods:
The arrows mark the periods: Fl (4) 8s Fl (4) 8s Oc (2+3) 10s Oc (2+3) 10s Iso G 4s Iso G 4s
All lighted aids to navigation are either
All lighted aids to navigation are either majormajor oror minor lightsminor lights, where major, where major lights are used for key navigational points along sea-coasts, channels and lights are used for key navigational points along sea-coasts, channels and harbour and river entrances. These lights are normally placed in lightships, harbour and river entrances. These lights are normally placed in lightships, lighthouses and other permanently installed structures, providing both high lighthouses and other permanently installed structures, providing both high intensity and high reliability of the lights. Major lights are then subdivided in intensity and high reliability of the lights. Major lights are then subdivided in prima
primary ry lightlightss (very strong, long range lights used for the purpose of (very strong, long range lights used for the purpose of
making landfalls or coastal passages) and
making landfalls or coastal passages) and secondary lightssecondary lights (shorter range(shorter range lights found for example at harbour and river entrances). Important details lights found for example at harbour and river entrances). Important details of (especially) primary lights can be found in a reference called
of (especially) primary lights can be found in a reference called the Lightthe Light
List
List where information (about pedestals etc.) can be found which is notwhere information (about pedestals etc.) can be found which is not
included in the chart. included in the chart.
Minor lights on the other hand are likely to be found within harbours, along Minor lights on the other hand are likely to be found within harbours, along channels and rivers. These have a low to moderate intensity and sometimes channels and rivers. These have a low to moderate intensity and sometimes mark isolated dangers.
mark isolated dangers.