Coastal navigation lrg

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  • 1. CHARTWORK AND FIXING Gruntproductions 2009 A Brief by Lance Grindley
  • 2. Gruntproductions 2009 CHARTWORK CONVENTIONS 140 (142) 0800 06 12 1.2 B 060900 06 Force 5 Planned TrackPlanned Track (To be made good):(To be made good): A bold thick line.A bold thick line. CourseCourse: Along the track.: Along the track. Course to SteerCourse to Steer: In brackets.: In brackets. SpeedSpeed: Vertically in a box.: Vertically in a box. DR (Dead Reckoning)DR (Dead Reckoning): Allowing for direction steered: Allowing for direction steered at speed through the water only and for NO OTHER factors.at speed through the water only and for NO OTHER factors. Tidal StreamTidal Stream: Three arrow heads from a tidal diamond,: Three arrow heads from a tidal diamond, show rate and effective time.show rate and effective time. WindWind:: EP (Estimated Position)EP (Estimated Position): Estimated from course steered through water,: Estimated from course steered through water, allowing for wind, tidal stream, current etc.allowing for wind, tidal stream, current etc.
  • 3. Gruntproductions 2009 CHARTWORK CONVENTIONS Distance to DestinationDistance to Destination Shown in milesShown in miles.. Expected time in a positionExpected time in a position DarknessDarkness Across the trackAcross the track Raising and Lowering of LightsRaising and Lowering of Lights Change of ChartChange of Chart 1810 SS Wolf Rock Lt 0547SR Chart 2052 230 0800
  • 4. Gruntproductions 2009 POSITION LINES Visual bearing from an objectVisual bearing from an object Visual bearing transferredVisual bearing transferred Radar range/VSARadar range/VSA Radio Fixing AidRadio Fixing Aid Astronomical position lineAstronomical position line SUN 0932 0900
  • 5. Position line by transit Ship f Gruntproductions 2009
  • 6. Gruntproductions 2009 CHARTWORK CONVENTIONS Potential DangersPotential Dangers - near track should- near track should be highlightedbe highlighted Safe DepthSafe Depth - hatch in- hatch in LDL for ship and HOTLDL for ship and HOT Clearing BearingsClearing Bearings - Solid arrow- Solid arrow heads towards object, NMT or NLTheads towards object, NMT or NLT Wheel over bearings (2)Wheel over bearings (2) - show- show position and est time with openposition and est time with open arrow head, show wheel if notarrow head, show wheel if not standardstandard 195(196) 181(182) 105(104) NM T 200 NMT176 NM T 160 140 090
  • 7. POSITION LINES LEADING TOPOSITION LINES LEADING TO FIXESFIXES Compass or Gyro bearing (3 or more)Compass or Gyro bearing (3 or more) Transit (must be sensitive)Transit (must be sensitive) Relative bearingRelative bearing Horizontal Sextant AngleHorizontal Sextant Angle Vertical Sextant AngleVertical Sextant Angle Range by optical instrumentsRange by optical instruments Range by raising/lowering of lightsRange by raising/lowering of lights (Horizon range)(Horizon range) Gruntproductions 2009
  • 8. Gruntproductions 2009 POSITION LINES LEADING TO FIXESPOSITION LINES LEADING TO FIXES SoundingsSoundings Astronomical position lineAstronomical position line Radar rangeRadar range D/F bearingD/F bearing Radio fixing aidsRadio fixing aids
  • 9. Gruntproductions 2009 USING CHARTSUSING CHARTS Always use the largest scale chartAlways use the largest scale chart appropriate to the purpose:appropriate to the purpose: Corrected first.Corrected first. More detail.More detail. Use nearest compass rose:Use nearest compass rose: Correct Variation.Correct Variation. Less projection distortion.Less projection distortion. Parallel ruler has less distance to travel.Parallel ruler has less distance to travel.
  • 10. Gruntproductions 2009 USING CHARTSUSING CHARTS Transfer position by range and bearing andTransfer position by range and bearing and Lat and Long.Lat and Long. Check unit of depth.Check unit of depth. Measure distance opposite latitude -Measure distance opposite latitude - Mercator.Mercator. Only one chart on the table at any one time.Only one chart on the table at any one time. Use soft pencil - Dont dig.Use soft pencil - Dont dig. Dont doodle !!!!Dont doodle !!!!
  • 11. Gruntproductions 2009 CHANGING CHARTSCHANGING CHARTS Transferred positions may be fix, DR or EP.Transferred positions may be fix, DR or EP. Transfer position by range and bearing andTransfer position by range and bearing and Lat and Long.Lat and Long. Note down position in Nav Record Book.Note down position in Nav Record Book. Plot onto new chart.Plot onto new chart. Fix to verify position as soon as practicable.Fix to verify position as soon as practicable.
  • 12. Gruntproductions 2009 The FixThe Fix 0926 Visual FixVisual Fix :: -made up of transits,-made up of transits, gyro bearings orgyro bearings or compass bearingscompass bearings Radar FixRadar Fix:: -made up of at-made up of at least threeleast three radar rangesradar ranges 0957
  • 13. Gruntproductions 2009 FIXINGFIXING Cross cut of 2 position lines. 3 positionCross cut of 2 position lines. 3 position lines are used as error check.lines are used as error check. Use Visual / radar conspicuous points.Use Visual / radar conspicuous points. Are points charted ?Are points charted ? Avoid blind arcs (visual and radar).Avoid blind arcs (visual and radar). Aim for a good angle of cut.Aim for a good angle of cut. Aim to fix at least every 6 minutes.Aim to fix at least every 6 minutes.
  • 14. Gruntproductions 2009 Horizontal Sextant AnglesHorizontal Sextant Angles AdvantagesAdvantages Potentially the most accurate method ofPotentially the most accurate method of fixing.fixing. Freedom from Gyro repeats.Freedom from Gyro repeats. Can be used in event of Gyro failureCan be used in event of Gyro failure.. DisadvantagesDisadvantages Takes longer to obtain the fix.Takes longer to obtain the fix. Manpower intensive.Manpower intensive. Requires three suitable fixing pointsRequires three suitable fixing points
  • 15. Gruntproductions 2009 Chord of a CircleChord of a Circle
  • 16. Gruntproductions 2009 HSA FIXHSA FIX 09000900
  • 17. Gruntproductions 2009 HSA FIXHSA FIX Plotted using:Plotted using: HSA Lattice chart.HSA Lattice chart. Douglas Protractor.Douglas Protractor. Station Pointer.Station Pointer. Beware of circular fixesBeware of circular fixes..
  • 18. When not to fix by HSA or bearingsWhen not to fix by HSA or bearings Possible Positions q q q f f f Gruntproductions 2009
  • 19. Gruntproductions 2009 Douglas protractor
  • 20. Gruntproductions 2009 FIXING BY RELATIVE ANGLESFIXING BY RELATIVE ANGLES Course030 G15 G45 G80 35 30
  • 21. Gruntproductions 2009 VISUAL FIXVISUAL FIX Duration of fixDuration of fix Ship Movement: Delay between first and last bearing been taken. Approx 10-15 Secs = 30 100m at 12 Kts
  • 22. Gruntproductions 2009 Sources of the Cocked HatSources of the Cocked Hat Reading Error:Reading Error: +/- 1/2+/- 1/2 approx 50 Meters at 3nmapprox 50