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6. Submarine Minelayers

6.1. UC-I class
Under international law, torpedoing a merchant vessel was considered an act of war against the nation whose flag this vessel flew. Laying a mine which killed the same vessel just as dead was not. This simple formula explains German enthusiasm for mine warfare, which resulted in the construction of over 100 submersible minelayers throughout the war. The beginnings of this development were extremely modest. The 1914 war emergency programme included fifteen minuscule minelaying submarines without any offensive armament; they carried twelve mines in six slightly inclined tubes forward, which were released gravitationally. At 170/180 ts, they were somewhat larger than the UB-I type. They were slow (6/5 kts) and short-legged (less than 800 nm at 5 kts), and seakeeping and habitability were just as bad as in the UB-I. Ten were built by the AG Vulcan yard in Hamburg, five by the AG Weser yard in Bremen. All were completed in 1915; there are no modifications on record.


None of the class remained under the German flag when the war ended. UC-1, UC-2, UC-3, UC-6, UC-7, UC-9, UC-10, UC-11, UC-14 and UC-15 were lost in action, UC-5 and UC-13 were lost by accidents, UC-8 was grounded in the Netherlands, salvaged and commissioned with the Dutch Navy as M-1, where it served till discarded in 1933. UC-12 was captured by the Italians the same way and incorporated into their Navy as X-1. This boat was mostly used for trials and scrapped after the war, but the Italians built two clones named X-2 and X-3 in the 1920s, one of which served till WWII. Tiny and primitive as they were, the UC-I boats managed to put a dent into allied shipping: Their mines destroyed a total of 281 merchants and the following warships: the Italian battleship Regina Margherita, the British light cruiser HMS Arethusa, a British, an Italian and a Russian destroyer, a Russian minelayer and a French and two British Minesweepers.

6.2. UC-II class
The follow-on design for a submersible minelayer was twice and a half as large as the UC-I type and - much unlike its extremely short-legged predecessor - enormously long ranged for its size. The new type was partially double-hulled. In addition to their six mine tubes, these boats also received torpedo tubes (two external, non-reloadable forward firing ones and a single stern tube with four reloads) and 88mm deck guns. Speed was no priority, so only modest engine power was provided for 12/7 knots. Like the UB-III type, the UC-II minelayers were built by five different yards to the same general requirements, but details were left to the respective builders, resulting in five sub-groups with the same layout, but many detail variations. Displacement was between 400 and 430 tons on the surface and between 480 and 510 tons submerged. As with the UB-III, range decreased with later boats.

6.2.1. UC-16 subgroup
Built by the Blohm&Voss yard of Hamburg, UC-16 through UC-24 had a range of nearly 9.500 nm at 7 kts; all were laid down in 1915 and completed in 1916. They were the only UC-II subgroup which initially had a rounded bow. All carried an 88mm gun upon completion. UC-16, UC-18 through UC-21 and UC-24 were lost in action in this configuration; UC-22 and UC-23 survived and were scrapped after the war.


Information about upgunning is vague; 'some' boats (referring to the entire class, not only this subgroup) reportedly swapped their 88mm gun with a 105mm piece; the most likely candidates for this would be the boats which were in home waters in 1918. Of this subgroup, this applies only to UC-17, which survived the war and was scrapped afterwards.


A follow-on batch consisting of UC-34 through UC-39 was also built by Blohm&Voss in 1915-16; they were slightly larger and had a range of more than 10.000 nm at 7 kts. They also carried an 88mm gun. None was likely to have been upgunned. UC-34 was scuttled at Pola in 1918; UC-35, UC-36, UC-38 and UC-39 were sunk. UC-37 was the sole survivor; she was scrapped in 1920.


The next Blohm&Voss built batch consisted of UC-65 through UC-73, laid down and completed in 1916. They were identical to the UC-34 batch, but had a sharknose bow for better seakeeping, like all other UC-IIs. They also retained the range of 10.000 nm at 7 kts. UC-65, UC-66, UC-68, UC-69 and UC-72 were lost; UC-67 and UC-73 survived the war, were ceded to the Entente in 1918 and scrapped.


The most likely candidates for upgunning would be UC-70 (lost late 1918) and UC-71 (survived the war but foundered on her way to the breakers in 1919).


6.2.2. UC-25 subgroup
The AG Vulcan yard of Hamburg built UC-25 through UC-33, UC-40 through UC-45 (both batches laid down 1915, completed 1916) and UC-74 through UC-79 (laid down 1916 and completed 1917). All had a sharknose bow and 88mm guns on completion. Of the first two identical batches, which had a range of 9.400 nm at 7 kts, UC-25 was scuttled at Pola in 1918, whereas UC-26, UC-29, UC-30, UC-32, UC-33 and UC-41 through UC-44 were combat losses. UC-27 was transferred to the Entente and scrapped.


The most likely candidates for upgunning from the first two batches were UC-28, UC-31, UC-40 and UC-45. The first three were transferred to the Entente and scrapped; the latter had already sunk in 1917 due to an accident, but been raised and repaired. UC-40 sank on her way to the breakers. UC-28 was only used for training throughout the war.


The third batch was slightly lengthened; despite this, range dropped to slightly under 8.700 nm at 7 kts. All were laid down in 1916; the first four were completed in this year as well, the last two in 1917. UC-76 and UC-77 were definitely lost in this guise; UC-74 survived and was scrapped, but likely not upgunned.


UC-75, UC-78 and UC-79 probably were. All three were lost in 1918.


6.2.3. UC-46 subgroup
UC-46 through UC-48 (laid down 1915, completed 1916) and UC-61 through UC-64 (laid down 1916, completed 1917) were built by the Weser yard at Bremen. Both batches were identical externally; range varied between 7.200 and 8.000 nm at 7 knots. Of those who retained their 88mm guns to the bitter end, UC-46, UC-47 and UC-61 through UC-63 were lost in action.


Two of the boats were likely to be upgunned. UC-48 was interned in Spain after battle damage and foundered on her way to Britain after she was surrendered. UC-64 was lost in 1918.


6.2.4. UC-49 subgroup
UC-49 through UC-54 were built by Krupp Germania at Kiel; all were laid down in 1916 and completed in 1917. Their range was 8.800 nm at 7 kts. UC-50 and UC-51 were lost as completed with their 88mm gun, UC-53 and UC-54 were scuttled at Pola in 1918. UC-52 went to the British after the war and was scrapped.


Only UC-49 was likely to have been upgunned with a 105mm gun. She was lost in action late in 1918.


6.2.5. UC-55 subgroup
The final six units of this class (UC-55 through UC-60) were laid down at the Imperial Yard at Danzig in 1916 and completed in 1917. They had a range of 8.700 nm at 7 kts. UC-55 and UC-57 lost in action in 1917.


The other four were around long enough to be re-armed with a 105mm gun. UB-60 was only employed as a TS. All were surrendered to the Entente and scrapped.


With a grand total of 1.787 merchants sunk by mines or torpedoes, the UC-II class was by far the most successful German submarine class. They also destroyed a significant number of warships: The French cruisers Chateaurenault and Kleber, the British cruiser HMS Ariadne, the British monitor HMS M15, eight British and two Russian destroyers, three French torpedo boats, a British and a French submarine, four British sloops, a French minelayer and a Russian minesweeper.

6.3. UE-I class
Parallel to the development of the UC-II type, a true oceangoing minelayer submarine of similar size than contemporary oceangoing attack submarines was designed. Unlike the double-hulled UC-IIs, the UE-1 was a rather primitive single-hulled boat with saddle tanks. The systems by which the mines were laid was more complicated, but not more effective than in the UC-boats. 38 mines were stowed in the aft part of the vessel and deployed horizontally through two stern doors; the conveyors needed electrical power to work, while the UC-II's mine tubes needed only gravity. Engine power was very modest, and speed was poor (10/8 kts); range was less than 6.000 nm at 7 kts, considerably less than the UC-II. The boats were extremely cramped internally and considered unreliable; their weak engines were frequently pushed beyond their limit and broke down. In addition to their mines, they had two external torpedo tubes above water (one forward starboard, one on the port side aft) and an 88mm gun. Eight of ten UE-IIs (U-71 and U-72 and U-75 through U-80) were built by Blohm&Voss. The first four looked like this:


U-73 and U-74 were built by the Imperial Yard in Danzig. They could be distinguished by their bow shape; otherwise they differed in details only. U-73 was lost in this configuration.


The last four Blohm&Voss boats were fitted with larger CTs and a different bow shape for better seakeeping. U-77 was lost in this configuration.


Like most German submarines, the UEs exchanged their 88mm guns for 105mm pieces in 1917; the UEs were also fitted with net cutters. U-75 and U-76 were lost in 1917, and U-71 became a French prize to be scrapped.




U-72 was the only boat of this type which was fitted with two guns in 1917, one 105mm and one 88mm. She was scuttled at Pola in 1918.


U-78 was lost in 1918; U-79 and U-80 became Entente prizes in 1918. The latter was scrapped, the former was commissioned into the French Navy as Victor Reveille and served till scrapped in 1935.


Primitive and unreliable as they were, the mines and torpedoes of the UE-I class were responsible for the loss of 138 allied and neutral merchants, including the hospital ship RMS Britannic, the sister of Titanic and the largest ship to be sunk in the first world war. UE-71 was additionally credited with two British destroyers, UE-73 with the British battleship HMS Russell and a British sloop, UB-75 with the British armoured cruiser HMS Hampshire (with which went to the bottom Lord Kitchener himself, en route to Russia), UB-79 with the British armoured cruiser HMS Drake and UB-80 with another RN destroyer.

6.4. UE-II class
As long-range oceangoing minelayers, the UE-I class was disappointing. A follow-on type to be laid down in 1916 was based upon a much enlarged version of the Ms-type attack submarine. Whereever the UE-Is were primitive, the UE-II class was sophisticated. They were large (1165/1510 ts), carried four reloadable front torpedo tubes and a 150mm gun in addition to their 42 mines (although there were some variations in gun armament, see below). Their minelaying system resembled UE-Is, which was not very satisfactory. Machinery was adequate, although their speed was mediocre (14,5/7 kts). Five (U-117 through U-121) were ordered from the Vulcan Yard in Hamburg, five more (U-122 through U-126) from Blohm&Voss, also at Hamburg. All except one were completed in 1918; U-121 was unfinished when the war ended. The first group differed from the second by their larger fuel bunkers, giving them a longer range of nearly 14.000 nm at 8 kts.


U-117 differed from her sisters by having an additional 88mm gun behind the CT.


None were lost in action; all were delivered to the Allies after the war. The Americans and Italians scrapped their allotment or used them up as targets (U-118 was originally a French prize, but was scrapped in Britain, because she had stranded at Hastings on her way to France), but the French commissioned U-119 as Rene Audry. Like all ex-German U-boats in French service, she was scrapped in 1935.


The second group featured some external differences and markedly shorter range (11.500 nm at 8 kts).


U-123 had an alternative gunnery fit of two 105mm guns. They also suffered no combat losses and were ceded to the Entente after the war. The British scrapped their four boats, but the Japanese commissioned U-125 as O-1 and used her for trials. She was scrapped in 1922, but the Japanese I-21 submarine minelayer type was based on them.


These boats came too late to have much of an impact on the war; between them, they were credited with 23 sunk merchants. The class was not repeated.

6.5. UC-III class
Although the UC-II class obviously delivered results, the German submarine command saw room for further improvement. For the 1917 and 1918 coastal minelayers, a reworked design was introduced. Size increased to 480/565 ts, and the hull shape was streamlined for better seakeeping and habitability; the same goal was pursued by relocating the external forward-firing torpedo tubes to an amidships position. Speed (11,5/6,5 kts) and range (nearly 10.000 nm at 7 kts) remained pretty much the same. The 105mm gun became standard issue. As with the UC-II, several yards were involved in the production of these subs, in this case the Imperial Yard Danzig (UC-80 through UC-86 were laid down in 1917, and UC-139 through UC-152 in 1918), AG Weser (UC-87 through UC-89, laid down in 1917) and Blohm&Voss (UC-90 through UC-118 laid down in 1917 and UC-119 through UC-138 laid down in 1918; another batch consisting of UC-139 through UC-192 were planned to be laid down in 1919). The Blohm&Voss design is the only one of which a linedrawing could be found, but external dimensions of all three types were entirely identical, so appearance was probably more uniform as with the UC-II type. Trials showed that the new design did not yield the expected results; the UC-IIIs were marginally better sea boats than the -IIs, but their torpedo tubes created a widely visible line of froth, and underwater stability was considered unsatisfactory. Worse, the redesign resulted in a delay at a crucial time; only sixteen of the 1917 group (UC-90 through UC-105) were delivered between July and November 1918, and none of them made a successful operational sortie.


All were delivered to the Allies after the Armistice and scrapped, except UC-90 and UC-99, both of which were briefly commissioned by the Japanese as O-4 and O-5 and used for trials, before they were scrapped as well.

Greetings
GD

And... wrap!

7. Cruiser submarines

7.1. U-127 class
After Germany had bowed to US pressure after the Lusitania affair and abandoned her first attempt at unlimited submarine warfare in 1915, a new kind of submarine capable of worldwide operations according to prize laws was needed. Good habitability for a large crew (including prize crews), good seakeeping and strong gun armament were required for this kind of warfare. To achieve this, the standard Ms-type submarines were upscaled by 50% and equipped with two 150mm guns to quickly overwhelm any resistance by armed merchants and escort vessels. Torpedo armament (six 500mm tubes), speed (17/8 kts) and range (10.000 nm at 8 kts) remained the same. They were considered very good sea boats with fine habitability and still quite maneuverable for their size; their crash dive time of 30 seconds was an excellent figure which would still have been world class in this size category in the following war. Three yards were contracted in 1916 with four boats each: U-127 through U-130 (1.220/1.550 ts) were built by Krupp, U-131 through U-134 (1.160/1.530 ts) by AG Weser and U-135 through U-138 (1.180/1.530 ts) by the Imperial Yard at Danzig. None of the Krupp- and Weser boats were ever completed; only the appearance of the Krupp-boats is known. The Weser boats were slightly smaller and would certainly have differed in sundry details.


Of the navy yard built vessels, U-135 and U-136 were commissioned in 1918. The other two remained incomplete. Neither completed U-boat received its as-designed armament. Both had only one 150mm gun.


Only U-136 had an additional 88mm piece aft of the CT.


Another batch of fourteen units of a stretched version of 1.340/1.830 tons was ordered in 1917 and laid down in 1918; none were completed. All were to have an increased surface speed of 18 kts and an increased range of 12.000 nm. Torpedo armament was as before in the Imperial Yard (U-213 through U-218) and the Weser (U-219 through U-224) boats.


The Krupp boats (U-225 through U-228) would have received an additional pair of 500mm torpedo tubes aft.


During the final days of the war, both completed units were called upon to end the mutiny on the battleships Helgoland and Thüringen by threatening to torpedo them; the German submarine force, where officers and ratings lived closely together and suffered the same catering, was unaffected by the 1918 mutiny and remained loyal to the end. Neither boat ever went on a war patrol, and both were surrendered after the war. U-136 was scrapped; U-135 was throroughly examined, stripped of all important fittings and eventually scuttled. The British considered her an excellent design, and the interwar US submarines USS Cachalot and Cuttlefish were heavily influenced by them.

7.2. U-139 class
Excellent as the U-127s were, their range was not much better than that of most Ms-boats, and worse than in some (particularly the Imperial Yard built boats). To effectively operate in sea areas like the South Atlantic, the US coast or even the Indian Ocean, much longer range was needed, resulting in a very large hull. The three prototypes for Germany's submarine cruiser programme - U-139 through U-141 - were ordered from Krupp in 1916 and completed between March and August, 1918 (they were built faster than the contemporary U-127s). They displaced 1.930/2.480 ts, were good for 15,5/7,5 kts and had a range of 17.700 nm. Like the U-127s, they were habitable and good sea boats. They had the standard torpedo battery of four 500mm tubes forward and two aft, and their as-designed gun fit consisted of two 150mm and two 88mm pieces. U-139 only received the 150mm guns.


She was ceded to France after the war and commissioned as Halbronn. Like all French prize subs, she was stricken in 1935 and scrapped.


The other two apparently received their 88mm guns. U-140 was sunk by the USN as a target, U-141 was scrapped in Britain after the war.


Apart from the first three units, the cruiser submarine programme consisted of another nine boats ordered in 1917 from Krupp (U-142 through U-144), Vulcan at Hamburg (U-145 through U-147) and AG Weser at Bremen (U-148 through U-150). Unlike all previous German submarine classes, these units all were of identical size and performance, regardless of builder; they probably all looked alike, too. Compared with the first three, they were faster (17,5/8,5 kts) and had a range of 20.000 nm; armament was the same. Only U-142 was completed on the day before the armistice; she was returned to the yard for scrapping immediately afterwards. The rest was scrapped in the respective yards.


The AG Weser boats, of which none was completed, would have had a third 150mm gun.


In 1918, another 28 boats of the class were ordered: U-173 through U-176 and U-183 through U-190 from Krupp, U-177 and U-178 from Vulcan/Hamburg, U-179, U-180 and U-195 through U-200 from AG Weser, and U-181, U-182 and U-191 through U-194 from Blohm&Voss. Again, the AG Weser boats were to receive three 150mm guns, the other ones only two; they would have been identical in every respect to the 1917 batch. Most were begun, but none was as much as launched.
Their impact on the German war effort was negligible. A total of 11 merchant ships were sunk by U-139; the other three made no operational sorties. For all their technical excellence, the concept behind them - building a submarine large and powerful enough to overwhelm armed merchants and Q-ships in a fair fight under the prize laws - was obsolete as soon as the USA had entered the war; ordering additional ones in 1917 and 1918 made no sense at all. With hindsight, spending the resources used for these 40 boats on 150 additional UB-IIIs, of which quite a lot could have been completed in 1917 and 1918, would certainly have been the smarter move.

7.3. U-151 class
Seven transport submarines to fetch strategically important materials in the still neutral USA were ordered in 1915. Only two of them were completed as such (see post in the Merchant Ships thread) and named Bremen and Deutschland. Bremen vanished without a trace on her first journey, Deutschland ventured twice to the USA. These boats were double-hulled and quite good sea boats with a cargo capacity of 800 tons; their speed was 10/7 kts (empty) in the cargo variant and their range 12.000 nm (measured at top speed). When the USA entered the war, the five uncompleted boats were redesigned to become submarine cruisers, and Deutschland was taken in hand to be retrofitted. The designators U-151 through U-155 and U-157 were assigned to them, Deutschland becoming U-155; although Bremen was lost before the American entry into the war, the number U-156 was not assigned, indicating that there was a contingency plan to take over all seven boats into the navy in case their raison d'etre vanished. All refit jobs were completed in 1917. The militarized version was up-engined for a speed of 12,5/5 kts, and their range was no less than 25.000 nm at 6 kts. They were fitted with two 500mm bow torpedo tubes, two 150mm deck guns and two 88mm guns; torpedo stowage and ammunition supply for the 150mm guns was exceptionally high, making them suitable as replenishment ships, although they were never used as such.


Deutschland (U-155) was refitted provisionally at first; she received no bow tubes, but had six holes cut into her outer hull, into which single-shot tubes were inserted (four firing forward and two aft); although the usual 24 reload torpedoes were carried, reloading these tubes was only possible via the muzzle, utilizing collapsible cranes and requiring a dead calm sea.


U-155 was brought to the same standard as the other ones in 1918. Like U-151 through U-153 and U-157 she survived the war and was ceded to the Entente afterwards. U-154 (torpedoed by a British submarine) and U-156 (mined) were lost in 1918. Although designated as submarine cruisers, they were more akin to submersible AMCs; despite their improvised nature however, they scored their share of kills. The seven units of this class sank a total of 127 allied or neutral merchants. In addition, U-156 is credited with sinking the American armoured cruiser USS San Diego.

7.4. 1918 projects for large submarine cruisers
During 1917 and 1918, some interesting monstrosities were dreamed up by German designers.

7.4.1 Project 47
Project 47 was the code for an enlargement of the U-142 type to 4.100 tons surfaced displacement. They were to have a speed of 18/9 kts and a range of 13.000 nm, an armament of four 150mm and two 88mm guns and ten 500mm torpedo tubes (four forward, two aft and four amidships firing forward slightly off-axis). Their most unusual feature was their armoured hull: 60mm sides at the waterline, 40mm near the deck edge, 20mm decks, 60mm CT and 50mm gunshields. No boats were ordered to this design.


7.4.2. Project 50
While the Project 47 was designed for the same kind of prize warfare as previous sub cruisers, the slightly smaller, but visibly longer Project 50 U-Boats followed no real requirement at all, not even an unrealistic one. Nevertheless, one prototype was ordered in 1918, but the war was over before the keel could be laid. The boat would have displaced 3.800/4.500 ts, mounted the same gun armament as the Project 47 and also featured an armoured hull, although no details are available except that the guns would not have gotten armoured shields. They would have received a turboelectric powerplant with four boilers and two turbine sets, plus two cruising diesels; to vent the steam exhaust they would have been fitted with a huge, raked funnel behind the CT. Designed speed was 24/9,5 kts; there is no data available about designed endurance.


Greetings
GD

Great work GD. As comprehensive a listing of German WW1 subs as I have ever seen. The unbuilt projects at the end are a bit of sugar on the top.

Impressive. And I don't even know what to say about the P-47 and P-50 designs, crazyness has never been so awesome.

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FAN-BLOODY-TASTIC work GD

Jolly WELL DONE Squire

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What an amazing thread. Excellent drawings with the potted history...
Pure dreamland stuff
Very well done GD

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Thank you Kim for the crest

"Never fear to try on something new. Remember that the Titanic was built by professionals, and the Ark by an amateur"

So this is why you had been quiet for a while.
The quality of each drawing is very satisfying, but add this to the sheer number of drawings and this is absolutely overwhelming, congrats, I salute your dedication.

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Hatsuyuki-class Escort Ships . . . <3

Simply stunning!

Excellent boats! Nicely drawn and very detailed, as usual!

AWESOME work, my friend! Can't wait to see what you come up with next!

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