Ship’s track.

The ship’s course line or “track” is a straight line drawn on a chart in the direction of it’s course. It has arrow heads pointing in the direction of the course and the course is written in along the track. The speed of the vessel is written in an enclosed box which is always orientated in a north/south direction. In the previous sketch (under dead reckoning) you can see the arrow heads and the course “090°” written above the “track”. The speed which is 8 knots is written in a box below the “track”.

Estimated position (EP).

This is the most accurate position that can be obtained by calculation and estimation only. It is derived from the DR position with allowance made for the effects of currents and tidal streams. Again it is an approximate position only. It is shown on the chart as a dot surrounded by a small triangle with the time and the letters “EP” written alongside it. The current vector is indicated by a straight line drawn from the DR position and has three arrow heads indicating the direction of the current. The speed or strength of the current is written in brackets. The length of the vector indicates the estimated distance the current would move the ship in a chosen time span.

Ship’s track with estimated position taking into account the direction and strength of the current.