Transcript Marine Navigation and Naval Operations I

Lesson 5: Navigation Instruments
Lesson 5: Navigation Instruments
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AGENDA:
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Measurement of Depth
Measurement of Direction
Measurement of Distance
Measurement of Speed
Applicable reading: Hobbs pg. 110-128.
Measurement of Depth
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Echo Sounder (fathometer)
Hand leadline
Lead Line
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Manual method of
determining depth
Also allows for a
sampling of the
bottom type
Measurement of Direction
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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
180T / 090R
090T / 000R
Measurement of Direction
Visual Bearings can be measured in:
0
- Degrees Relative ( # # # R )
0
- Degrees Magnetic ( # # # pstgc OR M )
0
- Degrees True ( # # # T)
The navigator must convert any of these types of
bearings to True before they can be plotted on the
chart.
Bearing Circle/Alidade
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Azimuth or Bearing Circle
Telescopic Alidade
Bearing Circle
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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
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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
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Compass
 Dividers
Plotting Instruments
Nautical
Slide Rule
Operation of Nautical slide Rule
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Given two of the following, find the third:
– Speed
– Distance
– Time
Measurement of Speed
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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 Speed
Impeller Log
Measurement of Speed
Pitometer (Pit) Log
Measurement of Speed
Doppler Speed Log
3 Minute Rule
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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
6 Minute Rule
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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.
SPD
D=
10
REVIEW
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What does a fathometer measure?
What does D=Speed x 100 tell you?
QUESTIONS??