Navigational aid

A navigational aid device comprising first, second and third progressively overlaying sheets of material, said sheets being relatively rotatable about a common axis and being respectively inscribed with first, second and third scales, said first scale being indicative of magnetic variation, said second scale being indicative of magnetic heading and said third scale being indicative of relative bearing, at least said second and third sheets being in the form of concentrically mounted discs, said third sheet being of a lessor diameter than said second sheet, said device further including two centrally mounted independently operable rotatable arms defining two movable radial lines intersecting said scales and said axis, said axis being defined by centrally located pivot means securing said sheets and arms together for rotation about said axis, said pivot means having a central aperture such that when said device is placed on a map the map location appearing on said axis is visible through said aperture to an operator using said device, said aperture permitting said operator to place a mark directly onto said map location through said aperture whilst said device remains in position on said map.