British adventurer Charlie Martell is stranded in the North Pacific Ocean, waiting to be rescued by the Japanese coastguard, after tropical storms capsized his boat. Fellow adventurer Sarah Outen was rescued from the same seas this morning.

Martell was attempting to row solo from Japan to San Francisco when the storm capsized his boat, automatically triggering the emergency alarm. Coastguards in Falmouth were alerted and passed the signals on to Japanese authorities, which began coordinating a rescue.

The double world record holder is currently 700 miles off the coast of Japan. It is hoped that the Japanese coastguards will reach him in the early hours of Saturday morning.

“As far as we know he was fine,” said Martell’s campaign manager, Adrian Bell. He told the Guardian that he believes Martell is injured and there is concern about the heavy seas.

No one has been able to make contact with Martell for 18 hours.

Bell told the Guardian: “We believe that is because the electrical system failed. Obviously we do worry in these conditions but, like Falmouth coastguard, this is what [the Japanese coastguard] do day in, day out. The job they are doing is what they are trained to do. We have every confidence in their ability to do it”

Outen was rescued from the North Pacific Ocean this morning.

She was attempting to become the first woman to row 4,500 miles from Japan to Canada. Outen had been at sea for 24 days when the tropical storm hit. She raised the alarm 500 miles east of Tokyo and was found by coastguards this morning.

“Sarah is now safe,” an official statement confirmed today. “Thank you for all your messages of support and a huge thanks to the British Embassy in Toyko together with the Coastguards in Falmouth and Japan for such a swift response and for getting Sarah aboard the recovery vessel safe and sound in difficult sea conditions.”