Plot true course and distance between two charted points

Bowditch Ch. 1 §102

Bowditch Ch. 1 §102 — Introduction to Marine Navigation Dead reckoning (DR) is the determination of position by applying course steered and distance run from a known starting point. DR accuracy degrades over time and must be confirmed by external fixes whenever possible.

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. 23 §2302

Bowditch Ch. 23 §2302 — Navigational Errors Set and drift describe the effect of current on the vessel's track. Set is the direction toward which the current is flowing; drift is the speed of the current. The vector sum of the intended course (course made good through water) and the current vector gives the actual course over ground.

Bowditch Ch. 24 §2402

Bowditch Ch. 24 §2402 — Currents The vector triangle for current correction is: course steered + drift vector = course made good. Inverting it: from course made good and drift, derive the course steered required to make a given track over ground.

Bowditch Ch. 4 §402

Bowditch Ch. 4 §402 — Nautical Charts The Mercator projection presents lines of latitude and longitude as straight lines crossing at right angles, with rhumb lines (constant bearings) appearing as straight lines. Distances must be measured at the latitude of the line, since meridian length varies with latitude.

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.