The Nauticator is a vectorial computer for the solution of spherical trigonometrical problems, designed by Captain Leiv Jernæs of the Royal Norwegian Navy, who is at present captain of the training ship M.S. Sjöveien, Oslo. The instrument has been designed particularly for the rapid reduction of astronomical sights, and the calculation of great-circle tracks, distances and vertices. It has been sent to the Institute to assess its value, and this note will discuss its value to the air navigator.