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Navigation Instruments: Measurement of Depth, Direction, Distance, and Speed

Learn about the different navigation instruments used to measure depth, direction, distance, and speed. Topics include echo sounder, hand leadline, bearings, radar-distance, stadimeter, plotting instruments, and speed logs.

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Navigation Instruments: Measurement of Depth, Direction, Distance, and Speed

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  1. Lesson 5: Navigation Instruments

  2. Lesson 5: Navigation Instruments • AGENDA: • Measurement of Depth • Measurement of Direction • Measurement of Distance • Measurement of Speed • Applicable reading: Hobbs pg. 110-128.

  3. Measurement of Depth • Echo Sounder (fathometer) • Hand leadline

  4. Lead Line • Manual method of determining depth • Also allows for a sampling of the bottom type

  5. Measurement of Direction • Bearing: the horizontal direction of one terrestrial point as measured from another, expressed as an angle from 0 to 360 degrees. • There are three references for bearings: • Relative • Magnetic • True

  6. 000T / 270R 270T / 180R 090T / 000R 180T / 090R

  7. Measurement of Direction Visual Bearings can be measured in: - Degrees Relative ( # # # 0R ) - Degrees Magnetic ( # # # pstgc OR 0M ) - Degrees True ( # # # 0T) The navigator must convert any of these types of bearings to True before they can be plotted on the chart.

  8. Bearing Circle/Alidade • Azimuth or Bearing Circle • Telescopic Alidade

  9. Bearing Circle • Telescopic Alidade

  10. Measurement of Distance Radar-Distance is obtained by a radio wave that is transmitted into the air and returns as an echo. The time interval between transmission and return can be converted into a physical range. Used for distance (range) only!! Not normally used for bearings

  11. Measurement of Distance STADIMETER Used to determine precise ranges between ships in formation

  12. Making an Observation with the Stadimeter • Distance is determined by: • distance = height of object / tan (angle)

  13. Plotting Instruments Parallel Ruler

  14. Plotting Instruments Parallel Plotter

  15. Plotting Instruments Parallel Motion Protractor

  16. Plotting Instruments • Compass • Dividers

  17. Plotting Instruments Nautical Slide Rule

  18. Operation of Nautical slide Rule • Given two of the following, find the third: • Speed • Distance • Time

  19. Measurement of Speed • Speed over Ground (SOG) = true speed • Speed through the water SPEED THROUGH WATER • Impeller Log • Pitotmeter Log • Doppler Speed Log • Shaft RPM SPEED OVER GROUND • Direct output of many electronic navigation systems (GPS, Loran)

  20. Measurement of Speed Impeller Log

  21. Measurement of Speed Pitometer (Pit) Log

  22. Measurement of Speed Doppler Speed Log

  23. 3 Minute Rule • The Distance in yards that a ship travels in 3 minutes (D) is equal to the Ship’s Speed (Spd) in knots multiplied by 100. D = Spd x 100

  24. SPD 10 D = 6 Minute Rule • The Distance in nautical miles that a ship travels in 6 minutes (D) is equal to the Ship’s Speed (Spd) in knots divided by 10.

  25. REVIEW • What does a fathometer measure? • What does D=Speed x 100 tell you?

  26. QUESTIONS??

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