Navigation and Seamanship

6.3.3. LORAN(Long-Range Navigation)

LORAN is a hyperbolic terrestrial radio navigation system developed by US Army in 1940’s. LORAN is an acronym for Long Range Navigation. The Loran position-fixing system was developed during World War II by the U.S. to aid marine navigation with the operating frequency 2 MHz, this system was known as Loran A. Then they developed Loran B system, which was a high-accuracy version of Loran A, was not implemented because propagation disturbances rendered cycle selection unreliable. The Loran C system is an improved system developed from Loran A to provide greater range and for accurate navigation. After the termination of LORAN A in 1980, Loran C quickly deployed. The current version of LORAN is LORAN-C. LORAN system is a net work of land based radio transmitters (one master and 2,3 or 4 slaves or secondary stations called a chain ). The LORAN system works with low or very low frequency bands raning between 90kHz - 110 kHz with the transmitting power of 400 - 1600 kilowatts. The operation range of LORAN system is more than 1000 nautical miles (1800 km). Many nations use this system, including the United States , Japan , and several European countries. Russia uses a nearly identical system to LORAN in the same frequency range, called CHAYKA .In India, Loran-c is functional at two places viz. Diamond Harbor, Calcutta (GRI 5543) and Dhrangadhra, Bombay (GRI 6042).