Buoyant Ascent by Hilbert Schenck

Buoyant Ascent by Hilbert Schenck (F&SF, March 1980) opens with its protagonist, Izzy Kaplan, trying to play possum:

The phone rang steadily in the dark bedroom and Molly Kaplan blearily brought her wristwatch dial close to a sticky eye. “Jesus, three thirty!” She waited, knowing it was a wrong number. Yet the damn thing kept going. “Shit!” She fumbled for the receiver in the dark, got it, reversed it twice, and finally managed a “Yeah?”
“Dr. Israel Kaplan, please. Cmdr. B.J. Smith calling, U.S. Navy.”
Molly could hardly believe it. “Listen, buster, it’s three-fucking-thirty in the morning!” she shouted in the general direction of the receiver.
A pause. “I understand that . . . is it Mrs. Kaplan? . . . but we have a very urgent emergency. I certainly wouldn’t call you at this time for any other reason.”
Molly, her temper thinning steadily, leaned over and flicked on the bedside light. A soft yet handsome woman in her late forties, she managed to squeeze her bowed, full lips into a fearsomely thin line as she stared at the silent form of her husband.
Izzy Kaplan was not, in fact, asleep, but he had convinced himself that a position of utter passivity coupled with an absolute minimum of respiratory activity would see him through whatever was stirring up his wife.
“Izzy!” shouted Molly, now running at full volume. “It’s the fucking Navy with some kind of super emergency for you. What the hell are you doing with them now? What’s going on?”  pp. 6-7

We learn that Izzy is a hyperbaric specialist, and the Navy have phoned him because one of their submarines has had an accident and is now lying at an angle 940 feet under the sea. There is bad blood between Kaplan and the Navy, but he agrees to help as one of his ex-students is on board, and is now in command after the death of the captain. After brief sex with his wife Izzy drives out to Quonset airbase to catch a helicopter to the USS Tringa, the huge catamaran mother ship for the DSRV (Deep Sea Rescue Vessel) the Navy hope to deploy. However, if that method isn’t feasible, an alternative method using ascent suits may have to be used:

Kaplan could now think of nothing but a high-speed ascent in the water column; the head back in the suit, the gas gushing up the throat, the continuous surge and snap and ripple of the fabric from the tremendous velocity drag. But the throat was the key. Form a tube. Think of forming a tube! The rain pattered steadily on the windows and the slick, black road curved smoothly, almost empty in the glare of the street lights.
Turning east for Quonset, Izzy considered the exit circle of error on the sea surface. How large would the arrival-location uncertainty be? Nine hundred and forty-feet times what angle? If they had to draw the rescue vessels back too far, an embolized escapee might die before they got him out of the water and into a decompression chamber. That data must exist, thought Izzy, at least for some six hundred-footers. We can extrapolate it.  p. 12

The rest of the story sees Izzy arrive on the Tringa only to have the Admiral in charge stonewall Izzy’s suggestion of a rehearsal for a backup buoyant ascent procedure (there is previous bad blood between the pair, and too much money has been spent on the DSRV project). Izzy therefore contacts his wife who works for (and is having an affair with) a Senator. During this conversation Izzy threatens to contact the press about the couple’s dalliance if the Senator doesn’t co-operate and lean on the Admiral.
Once Izzy gets his way, he is flown by fast jet to London Heathrow (which, apparently, has grown an “RAF runway”) to speak to a contact who can provide similar suits, and thereafter flies north to a diving company at Lochstrom in Scotland. There they put dummies in the suits, take them down to nine hundred feet, and troubleshoot the procedure. On the first ascent there is a pressure spike that would kill the escapees, but the very smart owner of the facility eventually (spoiler) works out that the flutter valves in the suit are slowing down the escaping air and modifies them.
The final, exciting part of the story sees Izzy back at the site of the accident to see the buoyant ascents (the DSRV has been unsuccessful). The first escapee, a woman, survives almost unscathed, but later there are casualties, some fatal; the last one out, after a period during which the weather has deteriorated and they have had to revise their surface rescue procedure, is Izzy’s student, Commander Ferguson. He suffers a spinal embolism and dies, even though Izzy enters the decompression chamber to treat him.
The final scenes see an overwrought Izzy lose his temper with the Admiral (who should have started the buoyant ascent rescue earlier), his wife, and the Senator (ill-chosen comments from both) before he goes to do the post mortem on his friend.
If you are up for a fast-paced, near-future techno-thriller with larger than life, shouty (and consequently non-PC) characters, and which oozes verisimilitude, then this will be right up your street. (PS It’s exactly the kind of story you should find in Analog).
****+ (Very Good to Excellent). 17,550 words. Story link.