The pair had left Hartlepool marina shortly after noon yesterday. But when their engine failed they quickly drifted into thick fog.

The hapless sailors phoned Hartlepool coastguard station, which was not staffed on Sunday, but by chance a worker picked up the message and alerted the RNLI.

The duo had no safety gear onboard the dinghy or any devices that would have alerted anyone to the fact they were in danger.

A Coastguard spokeswoman said: "They left a message on Hartlepool Coastguard station answer machine.

"That's a station that is not manned, but just by chance one of our team members played the answer phone back."

Hartlepool RNLI inshore and all-weather lifeboats were launched and rescued the pair within 10 minutes, towing the boat and its passengers, who were from Trimdon, safely back to shore.

An RNLI spokesman said that visibility was down to 200 yards at the time and that they had a lucky escape.

Hartlepool RNLI Lifeboat operations manager Mike Craddy added: "We recommend that anyone heading out to sea carry VHF radio at all times."

The Coastguard spokeswoman said: "This could have been far more serious.

"It was thick fog up there as it was, so a person on shore would not have spotted them.

"They put themselves in a dangerous situation and should have been more responsible."