His rowing companion Mr Humphreys, 32, from Clapham, London, previously spent four years cycling round the world, has written two books and run the Marathon des Sables, a six-day endurance race across the Sahara desert.
McRae filled in his time with appearances on the Dakar Rally across the Sahara Desert, and at the Le Mans 24-Hour Race, as well as intermittent one-off returns to the world rally championship.