Here's an exciting tale from Reuters, followed by an intelligent comment from a reader....

 11:56 28Apr10 RTRS-Hapless UK sailor takes a round trip
    LONDON, April 28 (Reuters Life!) - A man who thought he was sailing along the coast of southern England had to be rescued by emergency services after his motor boat ran out of fuel while repeatedly circling a small island in the River Thames estuary.
   The man, who had no nautical guides and only had a roadmap to navigate by, had been trying to sail from Gillingham, about 35 miles east of London, to Southampton on April 19 by following the southern coast of England.
   But he ended simply doing laps of the 36-square mile Isle of Sheppey a short distance away in the mouth of the Thames.
   Eventually a lifeboat and coastguard were sent to rescue him after he used up all his fuel and ran aground, officials said on Wednesday. He told them he had been trying to navigate by keeping the coastline to his right.
   "He was attempting to travel around the UK from Medway to Southampton and had somehow lost his bearings and ended up travelling around the Isle of Sheppey," said Robin Castle, a member of the local lifeboat station.
   "It seems he didn't have the usual maritime charts or navigational equipment."

 Paul Iredale points out in an email that this all seems rather likely to be untrue: "It takes the best part of a day to get around, and there's a bridge that you have to ask to be raised to get through at the end of it. The mud flats where he ran aground are just before the bridge. I have almost run aground there myself. He appears to have got about two thirds of the way around. Just talked to a guy at Sheerness lifestation who agreed and said he didn't know where the press got the idea that he went round and round the island. Another urban myth is launched."