Page 16 - 4798

Deflection Angles
They are measured from an extension of the back line, to the forward station.
They are measured to the right (c.w or +) or to the left (c.c.w or -) depending on
0
the direction of the route. They are always smaller than 180 , and the direction of
turning is identified by R or L.

Fig. 2.5 Deflection angles

2.3 Direction of a Line
The direction of a line is the horizontal angle between it and an arbitrary closed
reference line called a Meridian. (It is a line on the mean surface of the earth
joining the north and south poles).
Different meridians are used for specifying a direction:
True Meridian: It is the north-south reference line that passes through the
earth’s geographic poles.
Magnetic Meridians: defined by a freely suspended magnetic needle that is
influenced by earth’s magnetic field only.
An Assumed Meridian: can be established by merely assigning any arbitrary
directions. For example, taking certain street line to be true north.

Bearings
Represent one system for designating directions of lines.
A bearing is defined as the acute horizontal angle between a reference meridian
and the line. The angle is measured from either the north or south towards the east
0
or west, to give a reading smaller than 90
True bearings/Magnetic bearings/Assumed bearings are measured from True
/Magnetic/Assumed meridians.

14