Navigation system used by submersibles in famous project

To fulfill the needs of geologists and geophysicits involved in the FAMOUS project, French submersibles, ARCHIMEDE and CYANA have been adapted for this particular mission and equipped with a deep ocean navigation system, A transponders net is moored on the ocean bottom, calibrated and oriented ; this net is then located in geographical coordinates. A 3 transponder net is enough for an area of 20 square kilometers. Processing of data can be made by hand or computer. An accuracy of ten meters was obtained although the sea bottom was rough and rugged. The transponders can be released and moored again as the work area is moving.