Lesson 5: Navigation InstrumentsLesson 5: Navigation Instruments

AGENDA:– Measurement of Depth– Measurement of Direction– Measurement of Distance– Measurement of Speed

Applicable reading: Hobbs pg. 110-128.

Lesson 5: Navigation InstrumentsLesson 5: Navigation Instruments

Measurement of DepthMeasurement of Depth

Echo Sounder (fathometer) Hand leadline

Lead LineLead Line

Manual method of determining depth

Also allows for a sampling of the bottom type

Measurement of DirectionMeasurement 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

090T / 000R

180T / 090R

270T / 180R

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.

Measurement of DirectionMeasurement of Direction

Azimuth or Bearing Circle Telescopic Alidade

Bearing Circle/AlidadeBearing Circle/Alidade

Telescopic Alidade

Bearing CircleBearing Circle

Measurement of DistanceMeasurement 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 DistanceMeasurement of Distance

STADIMETERUsed to determine precise ranges between ships in formation

Making an Observation with the Making an Observation with the StadimeterStadimeter

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

Parallel Ruler

Plotting InstrumentsPlotting Instruments

Parallel Plotter

Plotting InstrumentsPlotting Instruments

Parallel Motion Protractor

Plotting InstrumentsPlotting Instruments

Compass Dividers

Plotting InstrumentsPlotting Instruments

Nautical Slide Rule

Plotting InstrumentsPlotting Instruments

Given two of the following, find the third:– Speed

– Distance

– Time

Operation of Nautical slide RuleOperation of Nautical slide Rule

Measurement of SpeedMeasurement 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

Measurement of SpeedMeasurement of Speed

Impeller Log

Measurement of SpeedMeasurement of Speed

Pitometer (Pit) Log

Measurement of SpeedMeasurement of Speed

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

3 Minute Rule3 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.

6 Minute Rule6 Minute Rule

D = SPD

10

REVIEWREVIEW

What does a fathometer measure? What does D=Speed x 100 tell you?

QUESTIONS??QUESTIONS??