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Lesson 5: Navigation Instruments. Lesson 5: Navigation Instruments. AGENDA: Measurement of Depth Measurement of Direction Measurement of Distance Measurement of Speed Applicable reading: Hobbs pg. 110-128. Measurement of Depth. Echo Sounder (fathometer) Hand leadline. Lead Line.

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Lesson 5: Navigation Instruments

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Lesson 5: Navigation Instruments


Lesson 5: Navigation Instruments

  • AGENDA:

    • Measurement of Depth

    • Measurement of Direction

    • Measurement of Distance

    • Measurement of Speed

  • Applicable reading: Hobbs pg. 110-128.


Measurement of Depth

  • Echo Sounder (fathometer)

  • Hand leadline


Lead Line

  • Manual method of determining depth

  • Also allows for a sampling of the bottom type


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


000T / 270R

270T / 180R

090T / 000R

180T / 090R


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.


Bearing Circle/Alidade

  • Azimuth or Bearing Circle

  • Telescopic Alidade


Bearing Circle

  • Telescopic Alidade


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


Measurement of Distance

STADIMETER

Used to determine precise ranges between ships in formation


Making an Observation with the Stadimeter

  • Distance is determined by:

    • distance = height of object / tan (angle)


Plotting Instruments

Parallel Ruler


Plotting Instruments

Parallel Plotter


Plotting Instruments

Parallel Motion Protractor


Plotting Instruments

  • Compass

  • Dividers


Plotting Instruments

Nautical Slide Rule


Operation of Nautical slide Rule

  • Given two of the following, find the third:

    • Speed

    • Distance

    • Time


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)


Measurement of Speed

Impeller Log


Measurement of Speed

Pitometer (Pit) Log


Measurement of Speed

Doppler Speed Log


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


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.


REVIEW

  • What does a fathometer measure?

  • What does D=Speed x 100 tell you?


QUESTIONS??


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