An estimated position is the best guess that you can make for the boat’s movement across the Earth’s surface.
To start with, the extra information that we need to allow for is the direction of the tide (set) and the distance it has carried the boat(drift).
You begin as for the DR, but at the end of the water track, you draw in the tidal vector. This is the line that represents the direction of the tide and the distance it has carried you. The tidal vector has three arrows, and the EP is indicated by a triangle around the position. An EP should also have the time and log reading of the time it was plotted.
It is sometimes impossible to obtain more than one LOP at a time. To determine the ship’s position with one aid to navigation we can use a running fix. However if a running fix is not possible, we can determine an estimated position.
An estimated position is based upon whatever incomplete navigational information is available, such as a single LOP, a series of depth measurements correlated to charted depths, or a visual observation of the surroundings.
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