Visual piloting — three-bearing fixes, danger bearings

Bowditch Ch. 1 §101

Bowditch Ch. 1 §101 — Introduction to Marine Navigation Marine navigation is the art and science of determining a vessel's position and conducting it safely from one point to another. Its four primary methods are dead reckoning, piloting, celestial, and electronic — modern voyages combine all four with electronic navigation as the principal real-time reference and the others as cross-checks.

Bowditch Ch. 1 §103

Bowditch Ch. 1 §103 — Introduction to Marine Navigation Piloting is navigation by reference to landmarks, aids to navigation, and soundings. It is the primary method used in confined waters where dead reckoning alone is insufficient and electronic positioning may be obstructed by terrain or interference.

Bowditch Ch. 13 §1302

Bowditch Ch. 13 §1302 — Radar Navigation The principal radar range scales used in piloting are 0.5, 1.5, 3, and 6 nautical miles. Short ranges give the best discrimination for collision avoidance; long ranges give the best landfall detection.

Bowditch Ch. 23 §2301

Bowditch Ch. 23 §2301 — Navigational Errors Navigational errors arise from instrument error, observation error, plotting error, computation error, and the basic assumption that the vessel has held the planned course. Cumulative errors must be checked against fixes whenever possible.

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.