Lesson 4: Visual Aids to Navigation

Learning Objectives: Upon completion of this lesson, the student will: Be familiar with the shapes and lights of the International Association of Lighthouse Authorities (IALA) Combined Cardinal and Lateral System of buoyage. Comprehend the use of buoys and beacons during piloting.

Learning Objectives: Upon completion of this lesson, the student will: Comprehend the identifying characteristics and significance of lighted aids to navigation and buoys. Apply correct procedures to identify and determine the computed visibility of a navigational light.

Significance of Nav Aids Nav Aid: Any device external to a vessel or aircraft intended to assist in determining position and safe course, or to warn of dangers or obstructions.

Use of Buoys/Beacons in Piloting The first objective upon sighting a NAVAID is to identify it. After PID - make use of it Use fixed aids to navigation and charted structures for shooting LOP’s whenever possible Bearings to buoys may be used to help clarify the navigation picture when no other objects are available.

Systems of Buoyage Two general systems: Lateral – Location of buoy or beacon indicated direction of danger it marks relative to the course that should normally be followed Cardinal – location of buoy indicated approximate true bearing of safe water from the danger it marks Lateral Markings – best for well defined channels best of well defined channels Cardinal Markings – Best suited for marking offshore rocks, shoals, islets and other dangers in and near the open sea

Lateral Systems of Buoyage Method: indicate the direction of danger relative to the course that should normally be followed. Uses: Indicate sides or junctions of navigable channels Indicate the safe side on which to pass a hazard Mark the approx. centerline of wide bodies of water

Lateral Systems US Lateral System  “IALA B” Red buoys mark the starboard (right) side of channels When returning from seaward Green buoys mark the port (left) side of channels Uniform Lateral System  “IALA A” The opposite of above

International Association of Lighthouse Authorities (IALA) Region “B” Region “A” Region “B” Japan So. Korea Philippines 2.1-11

Buoy and Daymark Shapes Shape Assists in Easy Identification. Assigned Certain Colors for Lateral Use. Remember : COLOR Identifies Use.

Channel Buoys

Port Channel Buoys

Stbd Channel Buoys

Safe Water Buoys

Preferred Channel Buoys

Preferred Channel Buoys

Cardinal System of Buoyage Uniform Cardinal System of Buoyage Method: Used to indicate the approximate true bearing of safe water from the danger it marks. Uses: Mark offshore rocks, shoals, and islets. Mark dangers in and near the open sea.

Cardinal Buoys The North cardinal buoy is black on top and yellow on bottom. The safe water lies to the north of this buoy.  

Cardinal Buoys The East cardinal buoy is black with a yellow band. The safe water lies to the east of this buoy.

Cardinal Buoys The South cardinal buoy is yellow on top and black on bottom. The safe water lies to the south of this buoy.

Cardinal Buoys The West cardinal buoy is yellow with a black band. The safe water lies to the west of this buoy.

Cardinal Marks Used in Conjunction With Compass to Mark Best Water. Yellow and Black in Color. Two Triangles for Topmark.

Isolated Danger Mark On or above an isolated danger Red and Black color Topmark: 2 black vertical spaced balls If lighted: Flashing (2) white light.

Special Marks Used to identify special areas: Military exercise, traffic separation scheme, etc. Color is yellow

Special Buoys Used to mark: Color is yellow Prohibited areas Limits of fish traps Cable crossings Anchorages Color is yellow Usually unlighted

Buoy Positions Position on chart is only an approximate position Anchored to sea bottom. Can drift off station Not to be used to obtain a fix!

Beacons (Daymarkers) Permanently fixed aids Size from Lighthouses to small day boards Readily visible and easily identified

RACON Buoys RACON’s are used in the U.S. for the following: to identify aids to navigation, both seaborne (e.g. buoys) and land- based (e.g. lighthouses) to identify landfall or positions on inconspicuous coastlines to indicate navigable spans under bridges to identify offshore oil platforms and similar structures All racons used by the USCG are frequency agile type, designed to measure the frequency of every incoming radar pulse, and transmit an approximately 25 microsecond Morse-encoded response less than 700 nanoseconds later back to the radar on that frequency. The Morse- encoded response is encoded such that the length of one dash is equal to that of three dots, and the length of one dot equals that of one space.

Positive Identification of Navigation Aids PID Criteria: DAYTIME Location Shape Color Scheme Auxiliary features Special Markings NIGHT Phase characteristic Period Color Daytime: The location, shape, color scheme, auxiliary features and markings of a NAVAID are used to identify its purpose. Night time: The light shown by the NAVAID becomes the primary source of identification. The light phase characteristic (the sequence or pattern of light shown within one complete cycle of light), duration of its period (length of time required for the light to progress through one complete cycle of changes), and its color are all used to determine the identity of the light. When you find a NAVAID, compare it to your position on the chart to assist in verifying your position!

Phase Characteristics of NAVAIDS Fixed (F.) - Shines with steady, unblinking intensity. Flashing (Fl.) - Appears as a single flash at regular intervals; the duration of the light is always less than the duration of darkness. Flashing lights will not flash more than 30 times per minute. Quick Flashing (Qk.Fl.) - Similar to a flashing light, but it shows more frequently to indicate a greater degree of cautionary significance. The duration of flash is less than the duration of darkness, and the light will flash at least 60 times per minute. Light Phase Characteristics: Fixed (F.) - Shines with steady, unblinking intensity. Flashing (Fl.) - Appears as a single flash at regular intervals; the duration of the light is always less than the duration of darkness. Flashing lights will not flash more than 30 times per minute. Quick Flashing (Qk.Fl.) - Similar to a flashing light, but it shows more frequently to indicate a greater degree of cautionary significance. The duration of flash is less than the duration of darkness, and the light will flash at least 60 times per minute. Interrupted Quick Flashing (I.Qk.Fl.) - A light that quick flashes six times, followed by a time of darkness, with a standard period of ten seconds. Group Flashing (Gp.Fl.) - Shows groups of two or more flashes at regular intervals.

Phase Characteristics of NAVAIDS Interrupted Quick Flashing (I.Qk.Fl.) - A light that quick flashes six times, followed by a time of darkness, with a standard period of ten seconds. Group Flashing (Gp.Fl.) - Shows groups of two or more flashes at regular intervals. Morse Code Occulting Light Phase Characteristics: Fixed (F.) - Shines with steady, unblinking intensity. Flashing (Fl.) - Appears as a single flash at regular intervals; the duration of the light is always less than the duration of darkness. Flashing lights will not flash more than 30 times per minute. Quick Flashing (Qk.Fl.) - Similar to a flashing light, but it shows more frequently to indicate a greater degree of cautionary significance. The duration of flash is less than the duration of darkness, and the light will flash at least 60 times per minute. Interrupted Quick Flashing (I.Qk.Fl.) - A light that quick flashes six times, followed by a time of darkness, with a standard period of ten seconds. Group Flashing (Gp.Fl.) - Shows groups of two or more flashes at regular intervals.

Lighted Nav Aids Phase Characteristics

Chart Symbology for Lighted NAVAIDS Lighted navaids have purple exclamation point ! or 1/8” purple circle over black dot. Floating Navaids: Fixed Navaids in ROMAN text Floating Navaids in italics text Flashing Navaids: Numbers indicate patterns of light flashes Occulting: numbers indicate the pattern of eclipses eg. F Gp Fl (2+3) or Gp Occ (2+3) 1

Special Purpose Lights Alternating Lights change color following a regular pattern airport beacons, harbor entrance lights Color of a Light - Only three colors are used on lighted navigation aids in the U.S. and most foreign waters - white, green, and red. All lighted navigation aids are symbolized on a chart either by a purple exclamation point or by a 1/8-inch purple circle superimposed over a black dot or small open circle, indicating the location of the light. The color of the light, if other than white, will be indicated by the abbreviations “R” for red or “G” for green. The abbreviation “W” is used in the Light List and List of Lights to indicate a white light. If no abbreviation given on chart, assume “W.”

SECTOR LIGHTS Sector limits are expressed in degrees true as observed from a vessel, not from the light! Red - Marks Danger Areas. Green - Marks Turning Points or Best Water Areas. White - Marks Good Water.

Ranges Used to mark the center of the channel. Consist of two fix dayboards some distance apart. The aft one is always higher than the front marker. Color varies: Primary International Orange and White. Range lights are two or more lights in the same horizontal direction situated in such a way that one is sighted over another when they are sighted in line. They are used mainly to mark straight reaches of a navigable channel between hazards on either side Draw pict on board and talk about, and use example….

RANGES Colors Various Are Listed Above. Alignment Is Shown on the Left.

Determining the Computed Visibility of a NAVAID Purpose: To be able to determine, in advance, when you should expect to gain or lose sight of a navaid during a coastal transit. Computed visibility = The maximum distance at which a light can be seen given the current meteorological conditions. NOTE: Computed visibility  Meteorological Visibility When operating in coastal waters, navigators need to know when they can expect to first see and then lose sight of a navigational light. Thus, they want to know the computed visibility - the maximum distance at which a light can be seen in the current meteorological conditions.

Determining the Computed Visibility of a NavAid Horizon distance = the LOS from a position above the earth’s surface to the visual horizon. Geographic range = the maximum distance that a light may be seen in perfect visibility by an observer’s eye who is at sea level. Computed range = the distance at which a light could be seen in perfect visibility (taking into account elevation, observer’s height of eye, and the curvature of the earth). CR = Horizon Distance + Geographic Distance The computed visibility is always the lesser of the luminous range and the geographic range.

Determining the Computed Visibility of a NavAid Luminous range = the maximum distance at which a light may be seen under under the current meteorological conditions. Nominal range = a special case of the luminous range. It is the distance a light could be seen in “clear” weather. Also called the charted range. Appox 10 nms. Computed visibility = The maximum distance at which a light can be seen in the current meteorological conditions. The computed visibility is always the lesser of the luminous range and the geographic range.

Determining the Computed Visibility of a NAVAID First: Obtain the light’s intensity, its elevation above water, and the luminous range of the light from the luminous range diagram. Coast Guard Light List usually gives nominal range. Use the Luminous range scale and find the Luminous range using the nominal range and the Meteorological visibility on the scale. This scale is found in the Light list.

Second: Find the geographic range of the light by adding together the two horizon distances of both the light and the observer as follows (using Table 12 on p. 94 in Hobbs): Geographic range = the maximum distance that a light may be seen in perfect visibility by an observer’s eye who is at sea level.

Determining the Computed Visibility of a NavAid The first step in using the Light List or List of Lights is to determine the luminous range from the luminous range diagram (Appendix A / shown in Hobbs, p. 92). The luminous range can be determined by entering the diagram at the top or bottom with the given nominal range.

Follow the nominal range value vertically until the appropriate visibility curve is intersected, then read the corresponding luminous range from the left or right hand side of the diagram. In our example, the light has a nominal range of 23 nm in 5 1/2 nm of visibility, so the corresponding luminous range is 15 nm. NOTE: the nominal range and luminous range are identical in 10-mile visibility. Use a nominal of 5/10/15/30 and meteorological of 3,4,5,6,7,8,9.

Visual Navigation Aids Final: compare the geographic range to the luminous range. The shorter range represents the computed visibility. The light has a corresponding luminous range of 15 nm and a geographic range of 20 nm. Therefore the computed visibility would be equal to the luminous range which is 15 nm. 11

Horizon distance = the LOS from a position above the earth’s surface to the visual horizon.

Luminous range = the maximum distance at which a light may be seen under under the current meteorological conditions.

Meteorological Optical range Table Code # Weather Yards/NM 0 Dense Fog < 50 1 Thick Fog 50-200 2 Moderate Fog 200-500 3 Light Fog 500-1000 4 Thin Fog .5-1 NM 5 Haze 1-2 NM 6 Light Haze 2-5.5 NM 7 Clear 5.5-11 NM 8 Very Clear 11-27 NM 9 Exceptionally Clear Over 27 NM

Visual Navigation Aids horizon ht of light 100 ft 11.7 NM Using the chart we know that this NAVAIDs visibility is, no matter what the height of eye is, 11.7 NM, anything after will depend on the observers height of eye. Note, enviromental conditions do play a role in the NAVAIDs visibility. Ie if it is foggy, no will probaly not see it as far when in that 11. 7 nm range if you height of eye is sea level, however the light puts out enough power to reach that far in normal conditions…. * geographic range in miles ** horizon distance in miles

Visual Navigation Aids horizon horizon distance 50 ft ht of eye 8.1 NM * geographic range in miles ** horizon distance in miles

Visual Navigation Aids Fourth: add the two horizon distances together to get the geographic range. horizon geographic range = 11.7 + 8.1 = 19.8 nm luminous range = 15 nm

Questions?

TYPES OF LIGHTHOUSES Cheseapeake Off Shore Lighthouse Cape Hatteras Lighthouse

CHARACTERISTICS Lighthouses: Called “LIGHTS” Found Along Most Coastal Areas There Are Two Categories of Lights: Major Lights Minor Lights

MAJOR LIGHTS May contain fog signals. Have unique color pattern for identification. Shape of the structure varies.

MINOR LIGHTS Called Secondary Lights. Low to Moderate Intensity. Used to Mark Harbors or Channels. Usually Integrated Into Buoy System by Color, Number, or Shape.

LIGHTS White Lights Are General the Primary Color. Sector Lights: Show Different Color Lights Over a Region. Identified on the Chart and Light List/list of Lights. Based on Compass Rose.* *Always from the Ship to the Light.

LIGHT TOWERS Oil Rig Type Structures May Contain Fog Signals, Radio Beacons, Racons, Helo Pad. Records and Reports Weather and Tide Data Used to Replace Old Lightships.

LARGE NAVIGATION BUOYS (LNB) Very large buoys Contains light, fog signal, radio beacon Records weather and sea conditions Used where light structures are too hard or expensive to use.

IDENTIFICATION Lights are given a certain characteristic comprised of : Color (Green, Red, Yellow, or White) Phase (Rhythm of light) Period (Time interval for the Phase). This will be measured utilizing a stop watch.

PHASES OF LIGHTS There are several phases: Fixed (constantly on). Flashing F - Flashing (Not More Than 30 Flashes/minute). QF - Quick Flashing (50-79 flashes/minute). VQF -Very Quick Flashing (80-159 flashes/minute). FL(2+1)- Group Flashing (Flashes in a Sequence). Occulting (Period of Dark Longer Than Period of Light). Isophase (Period of Dark Equal to Period of Light).

LIST OF LIGHTS Seven Volumes Information on Nav Aids OUTSIDE the U.S. Same Format As Light List Published Annually by NGA

LIGHT LIST Seven Volumes Information on Nav Aids in the U.S. and its territories Published Annually by Department of Transportation, U.S. Coast Guard

Review Types of Port and Starboard Channel buoys and markers. What is the difference between the Light List and the List of Lights?