The Terrible Hours

Bookshelf: The Terrible Hours

The Terrible Hours – Peter Maas

The Terrible Hours
The Terrible Hours

The Terrible Hours reads like a thriller, and chronicles the sinking and recovery of the Squalus, a top of the range US Navy submarine on the eve of World War II. It is also describes the career of Charles “Swede” Momsen, a navy officer and member of the US Navy Experimental Diving Unit who pioneered mixed gas diving using helium in addition to or instead of nitrogen, and made contributions to the development of the navy dive tables. Momsen also had a keen interest in submarine rescue techniques, and worked on a device known as the Momsen lung, and a diving bell that docks over submarine hatches now known as the McCann-Momsen (or just McCann) Rescue Chamber. Several high-profile incidents where submarines were downed in fewer than 30 metres of water but there was no way to rescue the trapped crew spurred him on in this regard. In fact, 700 submariners were lost between 1929 and 1939, in what became known as the “Coffin Service.”

The Momsen lung resembles a small life preserver, and enabled a submariner to exit the submarine and swim to the surface, breathing all the while from a rubber bladder roughly the size of a human lung (these dimensions prevented excessive buoyancy – leading to the bends – and made it possible for the submariner using the lung to inhale comfortably against the ambient water pressure). A substance that absorbs carbon dioxide kept the air in the bladder clean (the user both inhaled and exhaled into the lung), while a small oxygen cannister topped up the oxygen levels. When ascending up the life line from a great depth, it was necessary to pause at intervals to avoid getting bent. On the surface, the lung functioned as a floating aide.

The rescue chamber was essentially a diving bell with a rubber gasket that docked over specially designed escape hatches positioned fore and aft of the submarine. Once it was positioned, the hatch could be opened and crew could be transferred from the submarine into the chamber. It was this device that was used to raise the 33 surviving crew members of the Squalus in four successive trips (and not without incident). I couldn’t believe that the events I was reading about took place in May 1939 – I make the mistake of thinking that all technological innovation took place in the last 30 years, and take things like dive tables for granted. The truth is that (regarding dive tables), courageous and foolhardy individuals figured out the absorption and dissipation rates of nitrogen and helium in human tissues by actually doing the dives (in a chamber, most of them). Sometimes they got bent. Momsen did many of these test dives himself.

As James Hamilton-Patterson points out in his review of the book, Momsen is lionised by Maas to a degree that could be seen to detract from the massive team effort it took to rescue the surviving crew and then raise the submarine. I did feel that Maas gave due credit to Momsen’s divers, who went down alone, to 80 metres, on air, to perform complex manual tasks on the deck of the submarine. These men worked under very difficult conditions, fighting both nitrogen narcosis (some of the accounts of their actions at depth and the transcripts of the conversations they had with Momsen, who was supervising from the surface, are downright hilarious) and the build up of carbon dioxide in their helmets when they over exerted themselves. Most of the men worked with Momsen in the Experimental Diving Unit, and had thus all spent considerable time at depth and in a pressure chamber testing different gas mixes, ascent rates, and diving conditions.

The last portion of the book deals with the raising of the submarine from the ocean floor, where it lay at 80 metres, partially flooded. The logistics of raising a 1,500 ton vessel half full of water are staggering, but after much trial and error it was done. The conning tower of the Squalus now stands as a monument in the navy yard in Portsmouth. The book contains several photographs taken after the rescue of the crew and during the raising and towing of the Squalus into port. There are more pictures here. There’s a YouTube slideshow of images and some of the history here, too:


Submarine rescue techniques have progressed a little bit since 1939. But sometimes to no avail – I am looking forward to reading Cry from the Deep by Ramsey Flynn, about the sinking of the Kursk a few years ago.

You can get a copy of The Terrible Hours here, and I promise you’ll read it in no more than two sittings!

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Lapsed mathematician, creator of order, formulator of hypotheses. Lover of the ocean, being outdoors, the bush, reading, photography, travelling (especially in Africa) and road trips.

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