Abstract: Device for positioning and orienting a boat on a navigational chart by data supplied by a communication via satellite (Global Positioning system), more commonly designated G.P.S., comprising two superposed disks, one serving as lower protractor (D1) provided with a North mark, the other as upper reader (D2), connected in their rotation center by an eyelet (24), two positioning rulers (R1, R2) punched by a longitudinal central aperture (4,5) and present on their edges a tenon which allows them to slide freely, each one in a mortised slide provided on each disk. During the positioning on the chart, the two disks are blocked (D1, D2) one against the other, the lower disk (D1) such as its North mark are placed in direction of the chart, the two rulers (R1, R2) are blocked perpendicularly one towards the other but with free slide. The disks are unlocked (D1, D2) during the orientation, and the upper disk (D2) can pivot with the upper niler (R2) which is used as orientation ruler.