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NAVIGATION TRAINING Section 4 Compass

Explore compass types, errors like variation and deviation, and conversions from true to compass headings. Enhance your navigational skills with this comprehensive guide.

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NAVIGATION TRAINING Section 4 Compass

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  1. NAVIGATION TRAINING Section 4 Compass

  2. Table of Contents • • Section 1 Types of Navigation • • Section 2 Terrestial Coordinates • • Section 3 Charts • • Section 4 Compass • • Section 5 Nautical Publications • • Section 6 Navigational Aids • • Section 7 Buoyage • • Section 8 Position Lines and Fixes • • Section 9 Tides • • Section 10 Currents • • Section 11 Weather

  3. Compass Types of Compasses • Magnetic Compass A compass that senses direction by interaction between its own permanent magnets and the earth’s magnetic field. • Gyroscopic Compass A electrical gyroscopic that is designed to seek true north

  4. Compass • Compass Rose • Sometimes called a windrose, is a figure on a compass, map, nautical chart or monument used to display the orientation of the cardinal

  5. Compass

  6. Compass Directional Reference Systems Relative Bearings (˚R) = bearings measured with reference to the ship’s longitudinal axis Magnetic Bearings (˚ M) = bearings measured with respect to magnetic north. True Bearings (˚ T) = bearings measured with respect to true of geographic north. Ship’s Head (or heading)= a special bearing denoting the direction in which the ship is pointing.

  7. Compass 000ºT True Bearings 270ºT 090ºT 180º T

  8. Compass Magnetic Bearings 000ºM Variation Easterly 270ºM 090ºM 180º M

  9. Compass 270ºR Relative Bearings 180ºR 000ºR 090º R

  10. Compass Relative Bearings Port Beam Right Astern Dead Ahead Starboard Beam

  11. Compass • Magnetic Compass Error: Variation • • Variation is the angle between a magnetic line of force and a geographic (true) meridian at any location on the earth. • • Variation exists because the earth’s magnetic and geographic poles are not in the same location. • Magnetic anomalies in the earth’s crust also contribute to variation.

  12. Compass Magnetic North Pole True North Pole Notice that the two poles aren’t together. The magnetic compass points to the magnetic pole, and this gives us VARIATION.

  13. Compass Magnetic Compass Error: Variation

  14. Compass Magnetic Compass Error: Variation

  15. Compass Magnetic Compass Error: Variation

  16. Compass Magnetic Compass Error: Deviation •This is the angle between the magnetic meridian and the north line on the compass card. •Deviation is caused by the interaction of the ship’s metallic structure, electrical systems, metallic objects (such as a cell phone left close to the compass) with the earth’s magnetic field.

  17. Compass Deviation A ship’s compass also must deal with magnetic forces from the ship itself, e.g. magnets, electrical cabling. The sum total of these forces pulls the compass slightly away from magnetic north, producing DEVIATION.

  18. Compass Deviation Deviation will change in size, dependant upon the course of the vessel. Swinging of the ship and proper correction using soft and/or permanent magnets , deviation can be minimized.

  19. Compass Compass Conversions Compass to True 1. C D M V T (AE) Can Dead Men Vote Twice (at elections)? 2. C A D E T Compass Add East True

  20. Compass Compass Conversions Convert Compass Courses to True Courses - this also applies to bearings, using the deviation for the vessel’s head.

  21. Compass Compass Conversions Converting True to Compass T V M D C (AW) True Virgins Make Dull Companions (At Weddings)

  22. Compass Compass Conversions Convert True Course to Compass Course - this also applies to bearings, using the deviation for the vessel’s head.

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