How do you determine your position using a two-point radar fix?

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Multiple Choice

How do you determine your position using a two-point radar fix?

Two-point radar fixing relies on using two known landmarks and measuring both how far away they are and what direction they lie from you, all at once, so you can locate your position by triangulation. Start with two fixed landmarks whose positions are known on the chart. For each landmark you record the range, which is the distance from your vessel to that landmark, and the bearing, which is the direction from you to that landmark (or equivalently the direction from the landmark to you, 180 degrees opposite). Each landmark then defines a locus: the measured range places you somewhere on a circle centered on that landmark, and the measured bearing places you along a line that passes through the landmark in the opposite direction of the observed bearing. With two landmarks, you have two such loci; their intersection pinpoints your exact position. Using both range and bearing makes the solution robust and unique, since ranges alone could yield two possible points and bearings alone wouldn’t define a precise location without the reference frame from the landmarks. In short, you determine position by plotting the two lines (or circles) defined by the bearings and ranges to two fixed landmarks and finding their intersection—triangulation using two known references.

Two-point radar fixing relies on using two known landmarks and measuring both how far away they are and what direction they lie from you, all at once, so you can locate your position by triangulation.

Start with two fixed landmarks whose positions are known on the chart. For each landmark you record the range, which is the distance from your vessel to that landmark, and the bearing, which is the direction from you to that landmark (or equivalently the direction from the landmark to you, 180 degrees opposite). Each landmark then defines a locus: the measured range places you somewhere on a circle centered on that landmark, and the measured bearing places you along a line that passes through the landmark in the opposite direction of the observed bearing. With two landmarks, you have two such loci; their intersection pinpoints your exact position. Using both range and bearing makes the solution robust and unique, since ranges alone could yield two possible points and bearings alone wouldn’t define a precise location without the reference frame from the landmarks.

In short, you determine position by plotting the two lines (or circles) defined by the bearings and ranges to two fixed landmarks and finding their intersection—triangulation using two known references.

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