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Navigation Elements

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Navigation Elements Know the four elements of navigation. – PowerPoint PPT presentation

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Title: Navigation Elements


1
Navigation Elements
  • Know the four elements of navigation.

2
Overview
  • Earths Size and Shape
  • Position
  • Direction
  • Distance
  • Time

Position
Pt A
3
Earths Size and Shape
  • For most navigational purposes, the Earth is
    assumed to be a perfect sphere.
  • Measured at the equator, the Earth is
    approximately 7,926.41 miles in diameter, and the
    diameter through the poles is approximately 7,901
    miles.

4
Earths Size and Shape
  • Great Circles and Small Circles
  • Defined as a circle on the surface of a sphere
    whose center and radius are those of the sphere
    itself. It is the largest circle that can be
    drawn on the sphere.
  • The single most important aspect of great circles
    for navigators is that the arc, or piece of the
    circle, is the shortest distance between two
    points on a sphere.

5
Position
  • Lines of reference are necessary in order to
    locate specific points on the Earth.
  • These lines are known as parallels of latitude
    and meridians of longitude.
  • The numbers representing a position in terms of
    latitude and longitude are known as coordinates
    of that position.

North Penn N40-14.05, W075-18.58
6
Position
  • Latitude
  • Parallel with the equator are lines of latitude.
    Each of these parallel lines is a small circle,
    and they have a definitive location.
  • The equator is latitude 0o, and the poles are
    located at 90o latitude. Letter designators N and
    S are used to show which latitude is meant.
  • Longitude
  • The Greenwich Meridian is sometimes called the
    prime meridian, although it is actually the zero
    meridian
  • Longitude is counted east and west from this
    meridian through 180o

7
Direction
  • Direction is the position of one point in space,
    relative to another, without reference to the
    distance between them.
  • The points of a compass are not adequate for
    modern navigation. It has been replaced, for the
    most part, by a numerical system.

8
Direction
  • Since determination of direction is one of the
    most important parts of the navigators work, the
    various terms involved should be clearly
    understood.
  • Course
  • Heading
  • Track

9
Direction
10
Direction
  • Now back to our navigational maps
  • Lets say you are trying to get from Point A to
    Point B

11
Direction
  • A line that makes the same angle with each
    meridian is called a rhumb line.
  • Flying this sort of path results in a greater
    distance traveled, but it is easier to steer.
  • Between two points on the Earth, the great circle
    is shorter than the rhumb line, but the
    difference is negligible for short distances
    (except in high latitudes).

Rhumb Line Great Circle Line
12
Direction
13
Distance
  • Measured by the length of a line joining two
    points. In navigation, the most common unit of
    measuring distance is the nautical mile.
  • The nautical mile is about 6,076 feet.
  • Statute mile is 5,280 feet
  • Speed If the measure of distance is nautical
    miles, it is customary to speak in terms of
    knots.

14
Time
  • The Earth makes a complete rotation of 360o
    during a 24 hour day.
  • Greenwich Mean Time
  • Greenwich Mean Time (GMT) is the time of day at
    any given moment at Greenwich, England.
  • Zulu Time
  • Time zones are derived as /- from Zulu Time

15
Phonetic Alphabet and Morse Code
16
Navigation Elements
  • Know the four elements of navigation.
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