Through the mediacy of Professor Torao Mozai and the courtesy of Captain T. Iimura of Omron Tateisi Electronics, Tokyo, I was lent a prototype Omron lop NC Astro-navigation computer to evaluate during the course of a singlehanded race in Jester from Newport, Rhode Island, to Bermuda and the subsequent voyage back to England. Although it has been developed as an all-purpose navigation computer, the particular requirements of single-handed oceanic navigation might, it was thought, provide a useful commentary on this kind of instrument; and the environment of a small boat, so close to the sea surface and inevitably inimical to electronic equipment, would be an austere test of the instrument's seaworthiness.

This note is intended for navigators and so far as possible computer terms will be avoided. (The instrument is named a computer by its makers and will be referred to as such, rather than as a calculator, throughout.) The computer weighs 2·5 kg. and measures 200 × 289 × 91 mm. It operates from either the mains or batteries, and can be used for 10 hours continuously without a battery recharge.