Since Das Boot is regularly mentioned every page of this thread, and I already shared my thoughts about the modern TV series spinoff (pretty good, but gets pozzed/blacked during the last 2 seasons), now I just share my thoughts about the novel, which I read for the first time recently.
I read the English translation. As a translation, it's ok. My biggest complaint is that they convert all the metric measurements for depth, distance, weight, etc to English measurements,, which is a constant annoyance if you are accustomed to reading/thinking about U-boat stuff in metric. There are some occasional odd word choices and substitutions for translated technical terminology and naval jargon, but it's still pretty understandable overall.
The story is good. Naturally it's longer and more stretched out than the film.
The novel does a much better job of explaining the mechanics and workings of the U-boat's diving and underwater systems for the layman, especially the whole system of delicately balanced buoyancy and ballast tanks, which is a constant matter of life and death for the crew, even outside of combat. In the film, this aspect of the U-boat is reduced to "needle of depth gauge go up/down". In the novel, this is worked into the fabric of the story in a very natural way, and it is constantly being referenced and influencing the actions and direction of the plot, so you always know the buoyancy state of the boat.
The novel is also better at explaining and incorporating the whole 3-watch system for the crew. In the film, you have a vague idea that the crewmen are rotating on and off watch, but it's not exactly clear how that works or what they are all doing when on watch and off. And in the film, you get a general sense that the 1WO and 2WO are helping run the boat, but their role as leaders for 2 of the 3 watch groups is much clearer in the novel.
Also the role of the different command officers and technical officers on the boat is better explained and incorporated into the plot in the novel, besides giving those officers more characterization.
The iconic torpedo-attack and depth charge combat sequences in the novel are much the same as in the film, but explained in way more technical detail, so you have a very clear mental picture of the relative position of the boat and the target convoy, the defending escort destroyers, and the sinking depth charges. However, it's also explained in the book that the narrator character only has this comprehensive situational awareness because he tends to be stationed in the control room (zentrale), near the captain during these sequences, so he can overhear all the orders and snippets of dialog between the captain and other officers.
And in fact there are some points when a lot of stuff is going on and only the captain, in his own mind, has a clear picture of where the boat is positioned in relation to the enemy ships, and the entire rest of the crew and officers (including the narrator) is left in a fearful staste of ignorance about what is going on and just has to completely trust the captain's judgment and orders. But in the film, this is like the default state of situational awareness for the audience.
All the iconic sequences, and even the less dramatic sequences in the film are directly adapted from the novel, but often condensed or shortened in length, and of course stripped of the narrator's internal monologue and thoughts. One that really stood out as being condensed in the film was the storm sequence, which is much longer and much more intensely violent and terrifying in the novel, with the deck of the boat boat being frequently pitched almost perpendicular to the horizon by the rough seas, which would have been recklessly dangerous to do with the film's moving U-boat set.
Much more types of large and small encounters, events, and actions involving the U-boat crew and other ships, places, people, wreckage, etc take place in the novel than in the film, and many of these are borrowed or reimagined in the TV series to pad out the running time.
The novel has a lot of sometimes lengthy flashbacks or stories from the different crew and officers and narrator character. Many of these are grossly sexual in nature, but that's probably true to life, with young men at war and on leave in France.
The narrator is very clearly an artist and painter (as the author was in real life), in his obsessively detailed descriptions of the sky and sea when his character is on watch, but that seems true to life, too, since scrutinizing the sky and sea for threats and targets was the primary preoccupation for much of the war cruise.
Only 2 parts of the story seem implausible to me, from my limited knowledge of the U-boat war. One is that the boat is frequently mentioned to be diving below the maximum crush depth of submarines of that era, like 3 times deeper, but it's a pretty minor error that can be easily overlooked and ignored.
The second and bigger issue is that the boat's war cruise is explicitly mentioned to be taking place in the winter of 1941 - 1942, which is constantly referenced in the plot. This is right at the start of the so-called Second Happy Time, when the U-boats were scoring spectacular successes against the poorly defended American convoys and shipping after months of worsening losses against the British, and U-boat crew morale was consequently recovering and rising for a change.
But the tone of the story more closely resembles a war cruise in 1943, when U-boat crew morale was very low, the French naval bases and German homefront cities were being relentlessly pounded by RAF Bomber Command every night, convoys were dangerously well-defended, and air attack at sea was a constant and fatal threat. In the novel, much is made of the fact that the highly celebrated, early war U-boat aces of 1939-40 are all dead by 1941, which is true, and that the U-boat fleet was running low on experienced officers and crews and already scraping the bottom of the barrel with teenage conscripts, which seems less likely for 1941.
It's very easy to imagine the story taking place in 1943, so it's a bit of mystery to me why it is so explicitly set in winter of 1941.
