A MAJOR Far East-based port authority is closely studying the feasibility of adopting Sea Information Systems (SIS) Microplot - a personal-computer (PC) based integrated navigation system. According to SIS, besides the system's vessel tracking feature, it was cost effective and also easy to use. ''The idea of PC-based navigation system is now being accepted more by the marine industry, an industry not noted for radical changes,'' said managing director of SIS Tony Cochrane-Barnett. SIS claims its Microplot navigation system had been proven in the harsh environments of the fishing, dredging and offshore oil industries. Fishing information from existing plotting systems can be transferred to Microplot format. The company says to simplify the navigator's task, Microplot had extensive voyage planning facilities, way-point navigation tools, DR plotting and dual tracking. SIS says the arrival of electronic charts on the marine scene had a dramatic effect on the way shipboard navigation was perceived. Microplot uses both live chart systems and is compatible with DX90 electronic charts, the latter being the standard agreed by the International Hydrographic Office. The company also offers advanced memory management systems which will allow Mircoplot to display as much information on screen as the memory capacity allowed. Using this system, a user can display about 200,000 items of positional information, layered as marks, coastlines, lines and datapoints on screen at any one time.