You take bearings on two lighthouses that lie almost in the same direction from your boat — only about 15° apart. Why is this a poor fix?

The LOPs cross at a shallow angle, so a small bearing error shifts the intersection a long way

Two bearings can never produce a fix — you always need a third to intersect at all

🧭 Bearings & the Three-Legged Fix

Recall from earlier that a fix is a confirmed position on the chart. But how do you get one when there's no GPS to trust? You build it from bearings — the compass direction from your boat to a landmark you can identify on the chart, like a lighthouse or a distinctive headland. Take the bearing with a hand-bearing compass and you'll get a value in degrees, say 040° to the lighthouse.

Here's the key idea: a single bearing doesn't tell you where you are — only that you're somewhere along one line. Draw a line on the chart from the lighthouse back along the reciprocal (040° + 180° = 220°), and you've drawn a Line of Position (LOP). You're guaranteed to be somewhere on that line, but it could be near shore or miles out.

Cross a second LOP from a different landmark and the two lines intersect at one point — that intersection is your fix. Navigators prefer a third bearing as a check. In theory three LOPs meet at a point; in practice small errors make them form a small triangle called a cocked hat. A tight cocked hat means a trustworthy fix; a big one warns you to re-check your bearings.

Bearings work best when the landmarks are spread wide apart — ideally around 60–120° apart as seen from the boat. Two landmarks nearly in line with each other give LOPs that cross at a shallow angle, so a tiny bearing error smears your fix over a long distance.