July 1945: Stepping aboard a captured German U-boat

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The Engineer didn’t hold back on its praise for a German U-boat at the end of the Second World War

After almost a decade in which, presumably for reasons of national security, The Engineer studiously avoided discussing the technological advances made during the Second World War, the publication was finally free to look back at some of the engineering strides taken during the conflict.



And it’s notable that one of the first developments to catch its eye was not one of the many technical advances that swung hostilities in the Allies favour, but a marvel of German engineering: the U-boat.

After stepping aboard a captured U-3008 – one of the most advanced versions of the Type 21 U-boat – The Engineer didn’t hold back in its praise of a boat that it described as “revolutionary in many points of design and performance”, and bristling with features that “would make the mouths of British submarine officers water”.

Indeed, so advanced did The Engineer consider the vessel that it was moved to reference science fiction. “Some of the capabilities of the U-boats of this type are almost reminiscent of the fancies of Jules Verne: nine months below the surface, capable of 16 knots under water in emergency and safe at a depth of 900ft.”

The article goes on to discuss some of the key technical innovations of the vessel, and begins by commenting on its “phenomenal” speed. Interestingly, the boat’s surface speed was slow by comparison with British and US subs.

But, remarked The Engineer, “this submarine was not designed to come to the surface except when entering or leaving harbour” and its submerged speed was a ground-breaking 16 knots, around twice the top speed of existing submarines. The article puts this down to the number of batteries on board and the grouping of the cells.

Some of the capabilities of the U-boats of this type are almost reminiscent of the fancies of Jules Verne

The article also comments on the boat’s ability to rapidly accelerate and decelerate without altering its depth. Typically, with existing submarines, a sudden increase in speed would cause the bows to rise, largely due to increased pressure above the line of thrust of the propellers caused by the conning tower and the bridge. This didn’t seem to be a problem for the Type 21 as the engineers had cleverly found a way to automatically adjust the hydroplanes when acceleration began to take effect.

The vessel was also immensely strong, reported the article, thanks largely to an innovative figure-of-eight hull design. “The section amidships consists of the usual circular section pressure hull, with beneath it another smaller circular section pressure hull,” wrote The Engineer. “These two circular section hulls are not separate, and, in effect, they form part of the same ‘figure-of-eight’ sectioned pressure hull. Each part is not only immensely strong in itself; they are joined by very strong plating which is worked on a curve so that there is no weakness at the junction of the two parts of the hull.”

Finally, the article spares a thought for the mariners who lived and worked on the vessel, and remarks that they actually enjoyed relatively spacious and comfortable quarters. “If a submarine is designed to remain at sea and submerged for very long periods, one of the primary considerations must be habitability and in the U-3008 there is a comfortable sprung bunk for every member of the crew, and every bunk is provided with a fitted mattress.”

The Engineer was impressed, but also keen to stress the achievements of Germany’s submarine builders shouldn’t reflect badly on British engineers.

“Nobody can visit the German ports without realising that a very high proportion of the whole

war potential of the country was devoted to the production of U-boats, and that designers and constructors had been given a far greater degree of freedom than has ever been accorded to them  on this side of the North Sea.”



By contrast, the magazine wrote, British scientific and engineering efforts were spread across a wider range of activity: “The contrast between Germany and Great Britain is one of highly specialised effort on the one hand, as against a potential which has had to be used sparingly in certain fields in order that there should be enough of everything."

German U-Boats caused havoc during the war, sinking vast numbers of merchant ships in the Atlantic, cutting off vital supply lines and reportedly bringing Churchill close to contemplating surrender. Interestingly though, it was the British broad-based approach to engineering and science that eventually won through, with the pioneering development of air to surface radar enabling bombers to target surfaced U-boats, breaking their Atlantic stranglehold and swinging the war back decisively in the allies favour.

Read more about the technologies that helped the Allies win the Second World War