Just hours after arriving in Norfolk, Virginia, at the end of a gruelling second leg of the Velux 5 Oceans, Sir Robin Knox-Johnston hinted that he might yet race round the world one more time. Already the first person to sail solo nonstop round the world, almost four decades ago, the 68-year-old has only to sail back across the Atlantic on the third leg into Bilbao to set another record as the oldest person to do so.

Although his first competitive race for 39 years has been dogged by equipment failure and bad luck, the challenge of racing his hi-tech Open 60, Saga Insurance, against a younger generation of sailors has clearly whetted his appetite for further adventure and competition. He does not feel he has done justice to himself or the legions of followers who have tracked Britain’s grand old man of the sea in the past six months.

“I’ve had great sailing, yes, but racing, no,” he said. “I’ve no regrets about taking on this challenge, but I don’t feel I’m really succeeding, so I might have to find another race.” The next major round-the-world solo race is the Vendée Globe in 2008. It will be tempting for a patriot Knox-Johnston to join the growing ranks of British solo sailors — Mike Golding, Alex Thomson and Dee Caffari among them — on the startline for a race that has been won only by Frenchmen.

Knox-Johnston feels, after 25,000 miles, that he is beginning to understand the capabilities of a boat that is so different from his beloved 32ft ketch Suhaili, which he sailed into Falmouth in 1968 and straight into the annals of maritime history.

In its way this voyage is turning out to be an epic at least the equal of Suhaili’s 313-day nonstop circumnavigation. Knox-Johnston intended to cut 200 days off that time, but if that estimate has proved optimistic so far, his belated arrival into Norfolk at the end of a fraught and treacherous 14,000-mile second leg has proved what Jimmy Connors, the twice Wimbledon champion who competed hard into his forties, once said about age being just a number.

Knox-Johnston was greeted at the quayside by Unai Basurko, the big Basque who had raced him through much of the Southern Ocean and up the western Atlantic, and by Bernard Stamm, the runaway race leader, as well as Admiral Sir Mark Stanhope, deputy supreme allied commander of Nato. The pontoons were lined with people eager to welcome the grand old man of the sea back safely into port.

“Last night I was in the middle of the Gulf Stream, bashing around and saying to myself: ‘I want out of this, I’ve had enough’,” Sir Robin said yesterday. “But I know after a few days away my enthusiasm will be rekindled and I’ll want to be back in there fighting again.”

Knox-Johnston, who took third place on the opening leg from Bilbao to Fremantle, finished the second leg after 75 days, 18 hours and 43 minutes in fourth place, frustrated by the problems that have stopped him being more competitive.

An early problem with the autopilot forced him back into Fremantle only 50 miles into the second leg and to absorb a mandatory 48-hour penalty imposed by the race organisers, who are led by Knox-Johnston himself.

Having given Basurko a 250-mile start, he had begun to inch himself back into contention for third place behind Stamm and the Japanese adventurer-sailor, Kojiro Shirai-shi, as the five-strong fleet headed into the depths of the Southern Ocean.

But more problems with satellite communications prompted anguished cries for a return to the days of sextant and pencil, his main method of calculating his position during his voyage on Suhaili in the Sunday Times Golden Globe race in 1967-68, and led finally to an unsched-uled stop for repairs to his mainsail and his weather routing phone in Ushuaia on the coast of Argentina. The fact that, sailing without updated weather information, he had just overhauled Basurko to move into third place only heightened Knox-Johnston’s irritation. “I can’t sail without weather, I can only sail, and that’s not what I signed up for,” he wrote in his daily log.

A tricky passage through the south Atlantic and the Doldrums, during which he celebrated his 68th birthday on St Patrick’s Day, cost precious miles. Every high pressure system that could have blocked his path did so, until even the irrepressible spirit of Knox-Johnston, whose daily missives from the race were always laced with humour and blasphemy in roughly equal measure, began to ebb away. By the time he had come within sight of the finishing line in Virginia late last week, he was, for the first time in his sailing life, close to physical and mental exhaustion.

“It’s been a total nightmare, as hard as anything I did on the whole voyage with Suhaili,” he said. “Everything that could have gone wrong, went wrong. The boat itself has been great and the interesting thing is that in the past few days I’ve been pushing a lot harder and she’s taken it. I’ve not learnt anything more about myself, but I have learnt a lot about the boat. She’s proved she’s capable of doing this, it’s up to me to prove it too. Age? So what? I don’t give a damn about that. I think I’m 48.”

Now faced with a 96-hour deficit through the 4,500-mile final leg, Knox-Johnston will need to sail 16% quicker than Basurko to reclaim third place before the finish in Bilbao, the Basque’s home port. “The Pope blessed the Armada in 1588, soI take comfort from that,” he said.

Knox-Johnston spent his first night on dry land for 76 days in a secluded house by a lake an hour from Norfolk, recharging batteries while his shore crew refit the boat in time for the final leg of the Velux 5 Oceans, which begins on April 15.

The man anointed “Olde Sea Dog of the Year” by Terry Wogan recently would not see it so clearly, but merely completing the course would be a significant victory over what Knox-Johnston terms “the youth fetish” of today. But the restless competitive soul of the ancient mariner might yet be provoked into one more lone turn around the world.