This article performs a proposed design of a communications system based on the Automatic Identification System (AIS), to control ships crossing Magdalena River in Colombia. Ships crossing the river will be monitored in order to track them in real time and receive information related (course, ship type, dimensions, speed, destiny, etc.). In this paper are presented studies concerning geography in Magdalena River with the aim of establish design parameters and the location of the base stations. Moreover, it is selected a scenarío in a specific place along the river, in which some simulations were made, to obtain signal levels in order to verify the system coverage in each case.