What is a Line of Position (LOP) used for?

• A. A line for predicting weather fronts.
• B. A line on which your position lies, derived from observations; used with another LOP to fix position.
• C. A line of latitude indicating distance to port.
• D. A line showing time to next fix.

Answer: (B)

In navigation, a Line of Position is a line drawn on the chart along which your position must lie based on a single observation. That line represents all points that could produce the observed measurement. Because one line doesn’t pinpoint an exact spot, you combine it with another independent observation to determine your actual location by where the two lines intersect. For example, measuring the bearing to a known lighthouse gives you a line of position; another independent observation, like a second bearing to a different object or a range to another beacon, yields a second LOP. The intersection of the two lines gives your fix. So the Line of Position is used to translate observations into a location by intersecting multiple LOPs.