In the wide estuary, position fixing with reference to shore objects to be viewed from the deck of a vessel, is very difficult. In 1983 KoPT introduced the Electronic Position Fixing System "Syledis" for position fixing of the vessels plying in the wide estuary of the Hooghly river.
Position fixing in the expansive waterway is very complicated, particularly when referencing shore objects visible from a vessel's deck. In response, KoPT developed the Electronic Position Fixing System "Syledis" in 1983 to aid vessels navigating the wide Hooghly river estuary.