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NAVIGATION AND CHARTWORK

NAVIGATION AND CHARTWORK. February 2012. CANADIAN COAST GUARD AUXILIARY - PACIFIC. Navigation and Chartwork. This powerpoint is not intended to cover this whole subject.

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NAVIGATION AND CHARTWORK

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  1. NAVIGATION AND CHARTWORK February 2012 CANADIAN COAST GUARD AUXILIARY - PACIFIC

  2. Navigation and Chartwork • This powerpoint is not intended to cover this whole subject. • While it covers the main pertinent points of the standard, the candidate is expected to be already familiar with nautical charts, symbols, and various methods of obtaining fixes using visual means, radar and other electronic navigational aids, as well as the nautical publications.

  3. Standard

  4. Standard • Comprehensive knowledge of charts, chart symbols and chartwork • Knowledge of bearings, ranges, fixes, running fixes, set and drift • Compass use • Knowledge and use of nautical publications • Navigate in all conditions with due regard for good seamanship

  5. Chart Information

  6. Chart Information • Chart 1 is the publication containing explanations of the symbols, terms and abbreviations needed to interpret nautical charts published by the Canadian Hydrographic Service. • Coxswains must be familiar with this document. • It is available online.

  7. Chart Information

  8. Chart Information

  9. Chart Information

  10. Chart Information

  11. Standard Chartwork Symbols

  12. Standard Chartwork Symbols

  13. Descriptions

  14. Taking Visual Fixes • Visual fixes with bearing taken at the same time. • Take bearings on the beam first, and those directly ahead or astern last. • When measuring objects to determine a line of position, measure first those which have the greatest rate of change in the quantity being measured; measure last those which have the least rate of change in that quantity.

  15. Dead Reckoning A method to forecast where the vessel will be, knowing true course and speed alone Fix 1010 DR 1030 Course 100T @ 30 knots 20 minutes at 30 knots = 10nm

  16. Estimated Position A method to forecast where the vessel will be, knowing true course and speed, set and drift Fix 1010 EP 1030 Course 100T @ 30 knots 20 minutes at 30 knots = 10nm Set 040°T at 6 knots 20 minutes at 6 knots = 2nm

  17. Allowing for Set and Drift A method to maintain the desired track allowing for set and drift Fix 1010 Course to make good 100 T Speed made good 31.5 knots Course to steer 115T Speed 30 knots Set 040°T Drift 6 knots

  18. Running Fix A method to find the vessel with two bearings off the same object or two different objects

  19. Running Fix 1 A method to find the vessel with two bearings off the same object or two different objects 1000 Bearing 1 010°T Course 300°T @ 30 knots

  20. Running Fix 2 Lay off second bearing taken at 1015 1000 Bearing 1 010°T 1015 Bearing 2 070°T Course 300°T @ 30 knots

  21. Running Fix 3 Lay off course and distance traveled to time of second bearing 1000 Bearing 1 010°T 1015 Bearing 2 070°T Course 300°T @ 30 knots (7.5nm)

  22. Running Fix 4 Move bearing 1 to end of course line and distance travelled - fix will be where two bearings cross 1000 Bearing 1 010°T 1015 Bearing 2 070°T 1015 Course 300°T @ 30 knots

  23. Running Fix 5 Set and drift can be added to the course and distance vector, and the transferred bearing line run from that. 1000 Bearing 1 010°T 1015 Bearing 2 070°T 1015 Course 300°T @ 30 knots

  24. Fixes and Cocked Hats

  25. Compass Work

  26. Compass Work • Remember that the steering compass deviation table will only be accurate if: 1. No major alterations of structure or wiring have been made to the vessel; 2. No metallic objects (walkie talkies, knives, etc.) have been placed close to the compass; 3. Time - a vessels deviation can change over time.

  27. Compass Work • The variation on this compass rose 021°E (1988 13’W). • What would the variation be today?

  28. Compass Work • What would be the deviation on a compass course of 315°C and a compass bearing of 000°C? 15.75 °E 2012

  29. Compass Work • What would be the compass course to steer, if the true course required was 200°T in 2012? 6°W

  30. Compass Work • Remember that the hand bearing compass will have different deviation from the vessels steering compass. 180°C

  31. Radar Navigation

  32. Radar Navigation • The variable range marker (VRM) should be moved out until it just touches the object to be measured - that will be the range.

  33. Radar Navigation • When taking fixes using ranges taken at the same time, measure objects directly ahead or astern first, and measure objects closest to the beam last. • This is different to visual bearings.

  34. Radar Navigation • Radar ranges off two objects should be as close to 90 degrees apart as possible, and with three objects about 60 degrees apart to obtain the greatest accuracy. • Identify points off the chart, before obtaining radar ranges, NOT the other way around. • Use two or more objects (points of land or small isolated islands) that can be positively identified, both on the chart and by the radar.

  35. Radar Navigation • Racons are receiver/transmitter (R/T) transponder devices that can be used as a navigation aid that shows on the radar screen. • Racons and their identifying Morse mark are indicated on marine charts. • Measure the range to the racon from the first dot or dash nearest your own vessel on the screen.

  36. Radar Visibility • Sight relies on light waves. • Radar relies on electromagnetic waves. • On our rescue vessels, the horizon for both is not far

  37. Radar Visibility • As such, care needs to be taken when measuring radar ranges over the radar horizon, unless the range being measured is a charted vertical face.

  38. Detection Ranges

  39. Detection Ranges for Low Antenna Heights • Tankers, bulk carriers, cruise ships 9–12 nm • Freighters, cargo ships, medium warships 6–9 nm • Lightships 4–7 nm • Trawlers, coasters, small warships 3–6 nm • Metal-hulled boats 3–4 nm • Wood, fiberglass boats with radar reflectors 2–4 nm • Large sized buoys with reflector 3–5 nm • Large sized buoys without reflector 2–3 nm • Medium sized fairway buoys 1–2 nm

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