Lesson 5: Navigation Instruments

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Lesson 5 Navigation Instruments
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Lesson 5 Navigation Instruments

• AGENDA
• Measurement of Depth
• Measurement of Direction
• Measurement of Distance
• Measurement of Speed
• Applicable reading Hobbs pg. 110-128.

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Measurement of Depth

• Echo Sounder (fathometer)
• Hand leadline

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Lead Line

• Manual method of determining depth
• Also allows for a sampling of the bottom type

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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

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

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Bearing Circle/Alidade

• Azimuth or Bearing Circle
• Telescopic Alidade

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Bearing Circle

• Telescopic Alidade

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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
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Measurement of Distance
STADIMETER
Used to determine precise ranges between ships in
formation
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Making an Observation with the Stadimeter

• Distance is determined by
• distance height of object / tan (angle)

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Plotting Instruments

• Parallel Ruler

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Plotting Instruments

• Parallel Plotter

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Plotting Instruments

• Parallel Motion Protractor

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Plotting Instruments

• Compass
• Dividers

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Plotting Instruments

• Nautical Slide Rule

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Operation of Nautical slide Rule

• Given two of the following, find the third
• Speed
• Distance
• Time

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Measurement of Speed

• Speed over Ground (SOG) true speed
• Speed through the water

• SPEED OVER GROUND
• Direct output of many electronic navigation
  systems (GPS, Loran)

• SPEED THROUGH WATER
• Impeller Log
• Pitotmeter Log
• Doppler Speed Log
• Shaft RPM

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Measurement of Speed

• Impeller Log

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Measurement of Speed

• Pitometer (Pit) Log

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Measurement of Speed

• Doppler Speed Log

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3 Minute Rule

• The Distance in yards that a ship travels in 3
  minutes (D) is equal to the Ships Speed (Spd) in
  knots multiplied by 100.
• D Spd x 100

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6 Minute Rule

• The Distance in nautical miles that a ship
  travels in 6 minutes (D) is equal to the Ships
  Speed (Spd) in knots divided by 10.

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REVIEW

• What does a fathometer measure?
• What does DSpeed x 100 tell you?

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QUESTIONS??