Sub down

The story, as reported by The Age (Australia):

A Russian mini-submarine with seven sailors aboard was trapped on the sea floor off the Kamchatka Peninsula on Russia's Pacific Coast after becoming caught on an unidentified object, navy officials have said.

Navy authorities were trying to determine why the military vessel, called a bathyscaph or mini-submarine, was stuck some 190 metres below the surface before starting rescue efforts, Pacific Fleet spokesman Captain Alexander Kosolapov said in televised comments.

He said it might have been caught on a cable or a fishnet.

Kosolapov said there was contact with the sailors, who were not hurt and that authorities were preparing to send down a similar vessel to assess the situation.

Conflicting reports said there was enough oxygen in the vessel to last between one to five days.

Kosolapov said there was likely enough air to last four days, because such vessels typically have oxygen supplies for 120 hours and the accident occurred when it was launched from a rescue ship during a combat training exercise, the Interfax news agency reported.

AP reports have several facts different, in particular saying that there is just one day's oxygen on board. Let's hope the AP has got it wrong, because one day is not a lot of time to put a rescue effort together. I could find very little online about the Priz class of submarines. From Jane's, in a section on rescue submarines:

Little is known about Russia's systems, one submersible of the Bester and five of the Priz class, which were involved in the failed rescue attempt on the Kursk. The Priz is thought to be operable either manned or unmanned, but is restricted by a battery endurance of just three hours. An upgrade has been proposed that will allow the Russian systems to dock with damaged submarines and improve their navigation equipment.

I found several references to either one or two Priz-class submarines being used in the Kursk disaster, attempting to rescue the crew. From my own time in the Navy (now almost 30 years ago), I know that our rescue submarines depended on a specific hatch configuration to "dock" into; our submarine fleet was all equipped with these hatches. I don't know if the Russian rescue subs depend on such specific equipment (or indeed, if our own still do). I'm rambling a bit, but what I'm thinking is that a sub-to-sub transfer sort of rescue is a really tough challenge, and possibly dependent on equipment configurations that may or may not be present. I'm hoping that it's possible to untangle the propeller of the down sub, so that it can get to the surface on it's own — that seems like a much more likely scenario than a transfer.

Whatever the mode of rescue, our fervent hope is that the rescue is successful and the seven trapped sailors can breathe the fresh air on the surface once more...