This rule's patented vertical and horizontal rolling motion simplifies course and plotting calculations, while the unique radial arm allows you to automatically include compass corrections in your course plotting. Dims: Length 13-7/8", Width 2-5/8", Thickness 1". Features: Patented four-way rolling motion Roller body has protractor markings and a nautical mile scale Radial arm has Loran interpolator scales and 200 millimeter rule Automatic compass corrections When radial arm and body are used jointly, the birola rule becomes a 440 mm (17") divider (approximately) A speed/time/distance table is included Easy to follow instructions Packaged in a protective, durable vinyl pouch
