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Steering Systems parts and accessories from leading manufacturers like Furuno, Northstar, RayMarine and Simrad.
Most modern navigation relies primarily on positions determined electronically by
receivers collecting information from satellites. Most other modern techniques rely on
crossing lines of position or LOP.
If the navigator measures the direction in real life, the angle can then be drawn on a
nautical chart
and the navigator will be on that line on the chart.
In addition to bearings, navigators also often measure distances to objects.
On the chart, a distance produces a circle or arc of position.
Circles, arcs, and hyperbolae of positions are often referred to as lines of position.
If the navigator draws two lines of position, and they intersect he must be at that
position.
fix is the intersection of two or more LOPs.
If only one line of position is available, this may be evaluated against the dead
reckoning position to establish an estimated position.
Lines (or circles) of position can be derived from a variety of sources:
- celestial observation (a short segment of the circle of equal altitude, but generally
represented as a line),
- terrestrial range (natural or man made) when two charted points are observed to be in
line with each other
- compass bearing to a charted object,
- radar range to a charted object,
- on certain coastlines, a depth sounding from
echo sounder or hand lead line
There are some methods seldom used today such as "dipping a light" to calculate the
geographic range from observer to lighthouse
Methods of navigation have changed through history.
Each new method has enhanced the mariners ability to complete his voyage.
One of the most important judgments the navigator must make is the best method to use.
The practice of navigation usually involves a combination of these different methods.
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