The Rapporteur Breton Sirius course ruler from L`Ocean simplifies navigation on nautical and aeronautical charts enormously. This plotter is a ruler, a triangle and a course triangle in one and combines ease of use with high precision. All you have to do is place the ruler on the course line and turn the 360° course disc until the degree grid is parallel to a meridian. Now you can immediately read off the corresponding angle on the course disc. Errors due to unintentional shifting of a triangle no longer occur with this navigation disc! The fixed multicoloured inscription is welded between the plastic discs and thus guarantees years of reliable reading. The course ruler is supplied with a detailed description (in English) and an instruction sketch.