German evaluation of HMS Seal

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Felix C
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German evaluation of HMS Seal

Post by Felix C » 04 Oct 2020 19:31

I presume there is a report somewhere of German opinion of HMS Seal.

Anyone seen it and can provide particulars?

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Re: German evaluation of HMS Seal

Post by Nitin_Shirsekar » 19 Dec 2022 12:39

You can read a fictional part of the German reaction to the capture of HMS Seal in my Ebook titled "Type XXI U-Boat (Electroboot) The story of the world's first true submarine capable of operating primarily submerged. : Part One" authored by me.

Extract Below:

Though all the vital equipment aboard the Seal, had been destroyed, a captured submarine, especially in wartime, held several secrets. The twelve unused 21 inch, Mark 8 torpedoes on board were a prize; and the Germans had only to open the torpedo loading hatch, or the canisters outside the pressure hull to extract their booty. But it would not work out so simply, for the Nazis!

The Unterseebootwaffe was quick to examine the captured torpedoes and after a speedy going over passed them on to the specialist from the TI and the TVA. The German technical teams that examined the torpedoes were impressed. The British ‘Type 3’ contact pistols, they admitted were simpler, and consequently more reliable, than their own, ‘Pi1’ impact (AZ) detonator / pistol trigger.
‘Sher gut! An important find!’ they reveled. But they also acknowledged the fact that the extensively damaged Seal, in itself was an old Grampus class minelaying submarine, whose keel laid in nineteen thirty-six, held no supplementary design potential, except that of her torpedoes! ‘Our ocean going, Type VII and IX Unterseeboote, are much more sophisticated’ they confessed.

Yet loath, to let an opportunity to besmirch the Royal Navy slip, the Nazi’s decided to use the circumstances of her capture, as a propaganda prop, by hyping the HMS Seal as the ‘only operational submarine to ever be captured by a sea plane’. The Oberkommando der Marine (OkM) in its wisdom decided to refurbish the Seal, albeit at a huge cost, as a Kriegsmarine UB class, training U-boat, which in their opinion, would not only demonstrate to the Kriegsmarine trainees, the fallibility of the Royal Navy crews who had allowed her capture, but would also reinforce the importance of destroying all vital equipment on board in the unlikely event of their U-Boat falling in enemy hands; radios, navigation equipment, target location and acquisition devices, official instructions and signal ciphers, had to go first! A point which they perhaps, wished to stress on their own Unterseeboote apprentices.

The radio message from Lt Cdr. Rupert Lonsdale of a possible scuttling with the added option of beaching his command in neutral Sweden, had been a blow to the Admiralty. The triumphant German announcement the next day, of the capture of Seal along with her crew, had been equally devastating.

As the Norwegian campaign drew to a close, the Admiralty drew a fair estimate of the extent of Germany’s torpedo failures, where a disproportionate number of premature detonations, far beyond the periphery of the targeted vessels had been observed by British vessels. Royal Navy escort skippers had also reported, confirmed U-boat sightings in the vicinity of merchant vessels, that had not resulted in successful attacks, despite the presence of opportune circumstances for such maneuver's, for which Unterseeboote were known. Having faced ‘magnetic torpedo detonator’ failures of their own, early during the war the Admiralty had opined, that magnetic torpedo detonation, required too many variables including benign geographical settings, to ensure consistent and fail-safe detonation, ‘time after time’! Until the lacunae could be set right, the Royal Navy had decided to stick to their time tested ‘impact pistols’, before the imperfections were ironed out, by early nineteen forty-two! The British were also struck by the realization that not all torpedoes fired by German U-Boats in the Norwegian campaign, would consist of magnetic (MZ) detonators, implying that even the contact (AZ) detonators and the depth keeping apparatus on the German torpedoes, was faulty! On analyzing the sequence of events leading up to the Unterseeboote attack failures, the Admiralty correctly surmised that ‘There were interesting reasons, for the numerous premature torpedo detonations and the glaring ‘missed opportunities, by the Germans!’ The twelve unused 21-inch, Mark 8 torpedoes aboard the Seal, therefore remained a source of their disquiet.
It was too late now, to speculate if the Admiralty had erred in approving Lonsdale’s actions over the radio, and of not having advised him to ‘fire off’ all his unused torpedoes, untargeted and un-fused into the void, allowing them to sink into the ocean, as their propellants expended, rather than leave them intact, for his captors, to scrutinize and evaluate at leisure. In an attempt to side-track the issue, the British put out a series of carefully worded broadcasts and press releases declaring the Seal and her equipment to be outdated and obsolete, in vain hope that the Germans would not probe too deeply into Seal’s main weapons. But the Admiralty’s fears were, to remain unfounded, for at least another year.

The Germans on the technical evaluation of the captured Type 3 pistol trigger, quickly realized that though the trigger was of a ‘sound and efficient’ design, it could not be mated to the G7 in its existing form and shape.

The British, impact detonator / pistol trigger at the apex of the Mk.8 torpedo, had a six bladed spinner with corresponding mechanism that was combined into a four bladed contact horn and two bladed cocking pistol, which rotated and tensed the firing pin spring during its run, to ‘kick back’ the contact rod on the detonator, when the contact horns hit a solid object, setting off the warhead. The hefty six bladed British spinners, so unbalanced the German G7 warheads, that every test run resulted in the torpedo burying itself into the seabed. The TI and TVA soon realised that an exact replication of the Type 3 design, would need several months of precise redesigning work to change the internal detonator assembly design, contact horn, firing pin, spring and kickback rod, to fit inside and balance itself with the weight of the G7 warhead, before the Germans could operationalize a new ‘Pi2’ (AZ) detonator / pistol triggers, in April, nineteen forty-three, fitted to G7 torpedoes.
The strategic gain of discovering an effective torpedo trigger early in the war, had now been lost and though the new ‘Pi2’ (AZ) triggers would work perfectly, the Unterseeboote offensive in the North Atlantic, by April, nineteen forty-three was on the verge of failure for want of a better Unterseeboote design. Obsolete and slow, the Type VII and IX, were now finding it impossible to venture into the vicinity of a convoy, without getting severely mauled. Had the reliable ‘Pi2’ (AZ) detonator / pistol trigger been available to the Unterseebootwaffe by the end of the Norwegian Campaign when the HMS Seal was yielding her little secrets, Dönitz’s Unterseeboote armed with a robust working torpedo, could have, unleashing a swathe of destruction in and around the seas of Britain, when the Royal Navy’s defenses was at its weakest. A war winning tactical advantage of crippling both the British mercantile marine and the Royal Navy; early in the war had been lost, due to a broken, untested weapon.

The different clauses of the “Treaty of Versailles” of June, 28, nineteen-nineteen, had also proved decisive in delivering colossal returns to the Allies. Scripted by the ‘Principal Powers’ the treaty, emasculated Germany’s development of underwater weapons. Article 181, forbade Germany from possessing ‘submarines’; Article 188, required scrapping of existing ‘submarines’ including those under construction with parts auctioned for non-military use; Article 191, forbade construction and procurement of ‘submarines’ while Article 192, forbade testing and developing of torpedoes.
These restrictive articles placed in the Treaty were a tribute to the precaution and prudence of the Allied statesmen of that time, who ensured its addition in Germany’s surrender terms. Had such restriction not been in place, Germany, with a robust, well-designed and rigorously tested torpedo and its attendant mechanisms and delivery systems, would have during the initial stages of the conflict, indiscriminately sunk British assets at sea, launching something of a ‘Blitzkrieg at Sea’.

Britain with her lines of communications severed would have found it impossible to protect the sovereignty of her islands as well as her monarchy. Forced to shift bases, to one of her far flung dominions, possibly Canada; a diminished Great Britain would have been coerced into relinquishing the stewardship of her empire as also the future conduct of the war to the leadership of one of her dominions, rendering the ‘effective return’ of its monarchy, to these subjugated islands, into jeopardy, perhaps forever.

A poignant reminder in today’s era, where treaties amongst like-minded nations, play a diminished role.

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