The instrument consists of a plotter mounted on a roller.
• The plotter contains distance scales at 1:20,000, 1:40,000 and 1:80,000 to fit the N.O.S. Coast and Harbor Charts and also an inch scale
• A semi-circular protractor is included for measuring courses and bearings against a meridian on a chart, and two quarter circle protractors for measuring courses and bearings against a parallel of latitude
• Courses and parallel lines are transferred and kept parallel by means of two rollers which are mounted on a slide axis
• Instructions included