Arthur Bowers is a crewman taking part in all seven stages of the Clipper Round the World Yacht Race. The incident happened during daylight hours. He was apparently off watch and had the intention of going below into the saloon. He then unclipped his harness before going below.
In unruly seas (and maybe always as a habit), one should clip on before going on deck, using a strong point adjacent to the companionway. When going below, the process should be reversed, ie., go below, then unclip the harness.
At that moment a rogue wave struck the yacht, sending Arthur hurling down the deck, through protective guard wires and into the icy water. He was wearing a life jacket, which inflated on contact with the water, but he was not wearing an immersion suit. Being in the Southern Ocean, this meant that, apart from the difficulty of finding him, there was only a limited time available to retrieve him because of the temperature of the water. At the time that he went overboard, the wind was blowing 25-30 knots, the waves were six to eight metres high. Hull and Humber was sailing with the a Yankee headsail, a stay sail and three reefs in the main. Read more here.