Sperry Marine Visionmaster FT ECDIS, User Manual

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ECDIS User Guide Navigation Tools
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Line Of Position
The geographic location of own ship can be
determined by using Lines of Position (LOP),
which are created by taking bearings and/or
radar measurements from own ship to suitable
objects. Visual bearings taken on fixed aids to
navigation or landmarks such as smokestacks
or towers are typically used for bearing LOPs,
while the distance to a distinct shoreline or point
of land measured by radar may be used for a
range LOP. When two or more LOPs are
created a fix of own ship’s position may be
obtained.
The active point used for calculating the LOP fix
will be a circle for bearing objects and a triangle
for range objects. A triangle inside a circle will be shown if both range and
bearing are measured to the same object.
The Line Of Position window is divided into two main areas. The upper part
LOP Data provides an Enhanced Position Entry control which allows user
selection of range/bearing for object location. This can be either from
querying the chart for point objects or by manually selecting an area of the
chart.
For each operator defined LOP position, an active point symbol will be
displayed. Each symbol will have a reference number i.e. LOP 1, LOP 2
etc. When the range or bearing data is entered, the time of entry is
indicated beside the symbol. The symbol remains fixed at the selected
location or charted object, but the time stamp moves with the line or circle,
based on the speed and course of the vessel.
Up to six LOPs may be drawn on the chart display, note that LOP reference
numbers in the LOP window may be greater than six depending on their
creation methods.