Three-bearing fix and cocked-hat triangle

Bowditch Ch. 13 §1301

Bowditch Ch. 13 §1301 — Radar Navigation Marine radar transmits microwave pulses and processes the echoes to display a plan-view picture of surrounding targets. Range and bearing to a target give a direct fix.

Bowditch Ch. 7 §701

Bowditch Ch. 7 §701 — Bearings and Lines of Position A line of position (LOP) is a line along which the vessel is known to lie at a given moment based on a single observation. A fix is the intersection of two or more LOPs taken simultaneously.

Bowditch Ch. 7 §702

Bowditch Ch. 7 §702 — Bearings and Lines of Position A running fix is a fix obtained when LOPs cannot be taken simultaneously. The first LOP is advanced along the DR track to the time of the second observation; the intersection is the running fix, less accurate than a fix from simultaneous LOPs.

Bowditch Ch. 7 §703

Bowditch Ch. 7 §703 — Bearings and Lines of Position Bearings to a single object can produce a running fix when the relative bearing changes substantially. The 'doubling-the-angle' technique uses two relative bearings; the distance run between them equals the distance to the object at the second bearing.

Bowditch Ch. 7 §704

Bowditch Ch. 7 §704 — Bearings and Lines of Position Compass bearings of an approaching vessel are the canonical method of detecting risk of collision. If the bearing remains constant and the range is decreasing (CBDR), risk of collision exists.

Light List — Articulated Light

Light List — Articulated Light Articulated Light A floating tower restrained by a sinker on the seabed, allowing limited pivoting. A more accurate position-keeper than a moored buoy.