Cocked Hat

The triangular area formed when three plotted position lines fail to intersect at one point.

The non-intersection reflects observational, plotting, timing, chart or identification errors and is a visible indication of uncertainty. A small cocked hat can suggest good agreement between the lines but does not prove that the underlying observations are accurate or independent.

The vessel’s true position is not guaranteed to lie inside the triangle, particularly where the lines share a systematic error. A navigator should assess the likely direction and size of each error, use danger bearings or a conservative position where appropriate, and obtain another independent fix.