Blind sailors Scott Duncan, 38, and Pamela Habek, 42, have set off from Mexico in Tournesol, a Valiant 32 ft cutter in a bid to make the first blind yachtsman’s circumnavigation.

Their boat is fitted with a talking GPS which will tell them their speed, position and distance from a waypoint; a video magnifying glass under which they view their charts and a radar which Duncan can read with the aid of a magnifying glass.

They both see less than 10 per cent of a person with normal vision and are making the trip – they set out from San Francisco – across the Pacific and Indian oceans, Cape of Good Hope, Brazil, Panama Canal, Hawaii and home – to inspire other partially sighted people to live out their dreams.