Museum Of Maritime Navigation and Communication

Loran C

The Loran C system came into side-spread use during the 1970's. A Loran C chain, called GRI (Group Repetition Interval) consists of a master station and two to five slave stations. The area covered is much larger that a Loran A station pair. At first an operator had to determine the time differences and plot them on a chart, as discussed above. But soon the time differences were calculated automatically and displayed continuously and could be plotted on a chart. Soon after, the time differences were converted directly into degrees and minutes of Latitude and Longitude. The absolute accuracy of Loran-C varies from 0.1 to 0.25 nautical miles. Repeatable accuracy is much greater, typically from 60 to 300 feet.

Coverage is continuous within the area of coverage but the Loran system is not used worldwide.

The Loran C system is also used by aircraft.

SI-TEX/KODEN – 787C

Manufactured by: SI-TEX/KODEN

Model: 787C

Serial Number: 2487

Digital Marine Electronics Corp. – Northstar 6000

Manufactured by: Digital Marine Electronics Corp.

Model: Northstar 6000

Operating Frequency: 100KHz

Power Requirement: 10-40 VDC 2 Amps

Loran C Navigator

A LORAN C Navigator is essentially a computer with pre-loaded data, contained in an enclosure along with the receiver.

The recieved data consists of time differences between two (or more) station pairs. One station of the pair is always the master station, the other is a slave station. Each LORAN C chain consists of a master station and two to five slave stations. The operator selects the optimal two pairs to obtain the data.

By matching successive fixes of the received data with the pre-loaded data, a navigator can show latitude-longitude, own ships speed and course, course to steer to a chosen way point, time to get to the way point. Some other functions may be available.

Furuno – LC-80