Position, Position Lines, and Terrestrial Navigation Flashcards

A complete set of vocabulary flashcards covering position lines, terrestrial fixing techniques, dead reckoning, estimated position, and running fix methods based on the lecture material.

Running Fix (RFIX)

A method of fixing the ship's position used when it is impossible to obtain simultaneous position lines or when only one fixed target is available.

Doubling the Angle on the Bow

A running fix method using relative bearings where the distance run between observations equals the distance off the object at the time of the second observation.

Four-Point Bearing

A refinement of the running fix, also referred to as bow and beam bearing, where the initial angle is four-point ($45^\circ$) on the bow and the second angle is abeam ($90^\circ$).

First Case ($22.5^\circ - 45^\circ$ Case)

A running fix special method, also known as the $7/10$ or $0.7$ rule, where $0.7$ of the distance run between bearings equals the distance off the object when abeam.

Second Case ($30^\circ - 60^\circ$ Case)

A running fix special method, also known as the $7/8$ rule, where $\frac{7}{8}$ of the distance run between the first and second bearings equals the distance off the target when abeam.

Third Case ($26.5^\circ - 45^\circ$ Case)

A special running fix case that refers back to the bow and beam bearing method.

Dead Reckoning

The process by which the ship is carried forward by courses and distances from the last known fix without taking into consideration other factors that may affect the vessel.

Dead Reckoning Position (D.R.)

The calculated position worked up from the last position that makes no allowance for current or leeway.

Error of the D.R. at the Time of Fix

The difference between the old D.R. position and the new FIX position.

Estimated Position (E.P.)

The best estimate of the ship's position after consideration is made of the effects of wind, leeway, current, and bad steering.

Transferred LOP

The process of transferring a line of position using the LOP, course, distance traveled, time interval, and speed.

Transferred COP

The process of transferring a circle of position using the COP, course, distance traveled, time interval, and speed.

Position

The location or place of a person or thing (like a vessel) at a given time.

Line of Position (LOP)

A line drawn on a chart at any point of which the ship is situated, derived from celestial observations, bearing lines, or range lines.

Circle of Position (COP)

A circle in which the vessel is situated, obtained by plotting the distance between the ship and the target as the center of the circumference.

RADAR

An acronym for Radio Detection And Ranging, used to obtain the distance and bearing of an object.

Stadimeter

An instrument used to measure the distance of an object when its height is known, utilizing a system of mirrors as in a sextant to bring two images into coincidence.

Fix

The vessel's position established on a chart by two or more bearings, ranges, or distances of known landmarks, defined by latitude and longitude coordinates.

Cross-Bearing Method

A method of fixing position using two lines of position obtained from simultaneous bearings of two suitable charted objects.

Cocked Hat Method

A method of fixing position using three lines of position from simultaneous bearings of three suitable charted objects, forming a triangle if there is a delay in taking bearings.

Bearing and a Range Method

A method of fixing position using two lines of position: a bearing line of one suitable charted object and a range line of two targets in range, using $3$ targets in total.

2 Ranges Method

A method of fixing position using two range lines from two pairs of targets in range, requiring a minimum of $4$ targets.

Bearing and Distance of the Same Object Method

A method of fixing position using two position lines obtained from a bearing line (LOP) and a distance circle (COP) of a single target.

Bearing and Distance of Different Objects Method

A method of fixing position using two position lines obtained from a bearing line (LOP) of one target and a distance circle (COP) of another target.

Relative Bearing and an Angle Method

A method of fixing position using a relative bearing of a target converted to a true bearing, and an angle between that target and another target converted into a true bearing.