'Escape is possible down to 600ft.'

Two main techniques could be used to save survivors in the stricken submarine, a former Royal Navy commander said yesterday.

Two main techniques could be used to save survivors in the stricken submarine, a former Royal Navy commander said yesterday.

"We are talking abouteither an escape by the crew themselves or a rescue by other submersibles," said Commander Jeff Tall, director of the Royal Navy Submarine Museum in Gosport, Hampshire.

"Given the depth and circumstances, I think it is more likely to be a rescue."

Commander Tall warned it would be a race against time to save the sailors stranded under the Arctic waters of the Barents Sea.

The most likely rescue method would be for groups of men to climb into an escape tower, normally located towards the rear on this type of Russian submarine.

A rescue craft would then dock over the top of the escape hatch and around 20 men at a time could be transferred. Submersibles can effect a rescue at depths down to 2,500 feet, according to Commander Tall.

In a similar situation the Royal Navy uses mini-submersibles to take food and air while they wait for larger vessels to evacuate the survivors.

The second escape option would be for men to put on individual pressure suits and climb, one or two at a time, into an airlock compartment. They would plug themselves into a valve which inflates their suits and gives them air to breathe.

Water is then allowed in to equalise the pressure so hatches can be opened and the escapee rises rapidly to the surface.

The suits are equipped with special radios which, on surfacing, are tracked by satellite homing devices. Some reports suggest that the submarine is stranded at a depth of 500-580 feet.

"Escape is possible down to 600 feet," Commander Tall said.

"Pressure and time are the killers in these situations. The suit takes care of the huge water pressures at this depth and the escapee is only in the water for a few seconds. Bang, and you are on the surface. You would lose your ear drums for a couple of days."

"The British practise this kind of escape, but I am not sure if the Russians rehearse escapes."

Even using state-of-the-art equipment, experienced divers have not exceeded depths of 320 feet for any length of time.

Admiral Carroll, director of the Washington-based Center for Defence Information, said yesterday: "We do not have any information about Russian rescue capabilities. The consensus here is that the submarine is too deep for unassisted escape. "The American Navy certainly has the capacity to rescue crews in these circumstances."

When asked if the Russians would ask for American help, Admiral Carroll said: "It is unlikely as their systems would not be compatible. Submariners are very secretive about their systems."

Commander Tall said that if the submarine is flooded the loss of steam reactors which generate power would cause the nuclear craft to be stuck on the bottom.

"A fall-back electric motor would not be powerful enough to propel the submarine away from the seabed," he said.

In 1942 a British naval engine stoker became the only person to escape from a shipwreck at 170ft without using any specialist equipment.

John Capes was aboard the HMS Perseus submarine when it was damaged by an explosion off the Greek islands. The other 59 crew members died, but he managed to flood the cabin before escaping through a hatch.