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# Lesson 5: Navigation Instruments - PowerPoint PPT Presentation

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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Presentation Transcript

• AGENDA:

• Measurement of Depth

• Measurement of Direction

• Measurement of Distance

• Measurement of Speed

• Applicable reading: Hobbs pg. 110-128.

• Echo Sounder (fathometer)

• Manual method of determining depth

• Also allows for a sampling of the bottom type

• 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

270T / 180R

090T / 000R

180T / 090R

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.

• Azimuth or Bearing Circle

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

Used to determine precise ranges between ships in formation

• Distance is determined by:

• distance = height of object / tan (angle)

Parallel Ruler

Parallel Plotter

Parallel Motion Protractor

• Compass

• Dividers

Nautical Slide Rule

• Given two of the following, find the third:

• Speed

• Distance

• Time

• 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)

Impeller Log

Pitometer (Pit) Log

Doppler Speed Log

• 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

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.

• What does a fathometer measure?

• What does D=Speed x 100 tell you?