Abstract: A navigational aid device of the type comprising a disc supporting a map, especially a chart, a protractor being movable over said map, a first carrier movable in the longitudinal direction of said disc, and a second carrier which is movable on said first carrier and in the transversal direction of said disc and upon which said protractor is rotatably journalled. Said first carrier consists of at least one ruler extending across said disc and situated upon said map and sliding means situated between said map and said disc and connected to said at least one ruler, said sliding means being provided with at least one guide member movable along track means provided on and extending longitudinally of said disc.