Cocked hat. When three or more bearings are taken from a moving ship, the resulting position lines will not as a rule meet in a point, but form a triangle. This triangle is known as a cocked hat. The name “cocked hat” probably refers to the type of hat worn by officers in the days…
Taking bearings. Bearings are taken using the azimuth circle fitted to the compass repeater. It is specially designed so that you can observe the object through a metal sighting V on top of a glass prism and the graduations on the compass card through the glass prism at the same time. It is also fitted…
Ship’s track. The ship’s course line or “track” is a straight line drawn on a chart in the direction of it’s course. It has arrow heads pointing in the direction of the course and the course is written in along the track. The speed of the vessel is written in an enclosed box which is…
The observed position. The position obtained by the intersection of two or more position lines obtained from the observation of heavenly bodies is known as the observed position. It is shown on the chart as a dot surrounded by a circle, with “Obs” and the time written next to it. Dead reckoning position (DR). A…
The position obtained from the intersection of two or more position lines obtained at approximately the same time is called a fix. The term fix can only be applied to a position obtained from the observation of terrestrial objects. It is shown on the chart as a dot surrounded by a circle, with the time…
The ultimate goal of the navigator’s activities is to produce a record of his voyage, be it either in the form of a paper or digital chart. This includes the planning and execution of the voyage and the monitoring thereof. Because of the international nature of sea voyages and the present trend to have multinational…
Compass bearings The angle between the direction of a place or object and compass north is called the compass bearing. As previously stated it is distinguished by the suffix (C) after the bearing. Like true and magnetic bearings it is written in three figure notation. In order to change a compass bearing to a true…
Variation Variation is defined as the angle between the true and magnetic meridians. It is said to be easterly if the direction of magnetic north lies to the east of the true meridian and westerly if it lies to the west. Variation can b e obtained from a special isogonic chart where all the places…
The instrument which is used to measure and display bearings/courses is known as a compass. There are two basic types of compass used at sea: The Gyro compass. The Magnetic compass. On large merchant ships it is not unusual for it to be equipped with two gyro compasses and one magnetic compass. The reason for…
Bearings can also be expressed in relative terms, ie bearings relative to the ship’s fore and aft centreline. All bearings on the port side will be prefaced with the word “red” and those to starboard, with the word “green”. They will be followed by the angle measured from the bow, ie a ship is situated…
