A 15-YEAR-OLD schoolboy on work experience and his dad are among five crew missing on a capsized oil rig ship in the North Sea.

Rescuers are praying for a miracle that the five could have survived in an air pocket in the stricken ship's hull.

A massive search operation resumed at dawn today but Aberdeen Coastguard said the chances of any of the five being found were "extremely slim".

Heat-seeking cameras are being used in a desperate search for any sign of the crewmen, while rescue helicopters are scouring the sea.

The Norwegian ship Bourbon Dolphin overturned at 5.20pm yesterday 75 miles west of Shetland, killing three crew members.

There were 15 Norwegian crew aboard the handling supply tug, which was undertaking a routine anchor-handling operation at the drilling rig Transocean Rather in fair weather conditions. It capsized just over a mile from the rig.

Ten crew were rescued from the ship but three were later confirmed as dead.

The seven survivors were airlifted to hospital in Lerwick, Shetland.

Early today, rescue services evacuated 72 of the 99 workers on the rig as a precautionary measure, leaving 27 essential staff behind.

The cause of the disaster is not yet known but there was no mayday call from the ship.

Royal Navy divers from Faslane on the Clyde are examining the Bourbon Dolphin, which is 250ft long and less than one year old.

The divers are looking at the condition of the ship with the help of a remote-operated vehicle fitted with a camera.

The ship had been working in the vicinity of the Rosebank oilfield when it capsized.

It is still connected to the rig by an anchor chain, said coastguards.

The Bourbon Dolphin is still afloat, suggesting there are pockets of air in the upturned vessel.

Sources confirmed a 15-year-old boy was among the five missing.

The boy is a pupil at Ytre Heroy High School in the small community of Heroy, on the west coast of Norway.

Headmistress Solvi Remoy said: "I heard early this morning this boy and his father were involved in this incident but nothing has been confirmed yet.

"It's very, very sad and very, very tragic.

"It's an awful day for us because we are a very tight-knit community.

"The teachers, the pupils and the staff, everyone knows the family involved, and everyone has been affected by this.

"The pupils are all being offered comfort from teachers and from the health department officials."

There are 230 pupils aged 13 to 16 at the school.

Eystein Thue, a journalist with Norway's best-selling Bergens Tidende newspaper, said: "This is the biggest story today in Norway.

"All the TV networks and newspapers are following it.

"It is a very passionate story because a father and son are among the five missing, and the boy is on a working week, which all teenage children do in Norway.

"We have had that confirmed from the police."