UC-II class U-Boat (1916)

The Type UC II were sixty-four coastal minelaying submersibles built in 1915-17, the second of three such main types. They were essentially a much improved versions of the tiny UC-I based on the UB-I. They mostly joined the Flanders flotilla, Pola Flotilla in the Adriatic. They were built with more redundancy with two shafts and carried 12 mines from five shipyards in ten different batches, with variations in dimensions and performance. Comparatively to their size, they sank collectively far more shipping that the UC-Is, more than 1,800 enemy vessels and circa over 2.1 million Gross Register Tons (GRT), making them on of the most successful submarine design in military history. But they paid also a heavy price, with 46 lost in action. In comparison the UC-I types sank 264 ships for 283,000 GRT. Based on this, Kaiserliches Marine staff prepared the muc larger and better UC-III which like the UB-III became the solid foundation for later interwar U-Boote designs and ultimately the Type VII.

SM U35 berthed to the U-Boat tender S.M. Amphitrite

Development

The concept of a minelayer submarine was pioneered by the Russian engineer Naletov prior to the Russo-Japanese war back in 1904. Albeit this was a small prototype, seeing the efficience of mines in this war, another design led to the acceptance of a large navy-specific minelayer submarine that became Krab, a more consistent design accepted but built from 1909 still as an experiment, and completed at last by Nikolaev Naval shipyard in 1915. In between, the Kaiserliches Marine was also interested in the concept and essentially designed their own program started on 18 August 1914. This became Design 35a, essentially a conversion of the already existing UB-I coastal submarine of 1914 into a minelaying version. It was not accepted immediately, indeed on 11 September Grand Admiral Von Tirpitz rejected the program, put on hold. However after the stunning successes of U-Boats in the opening weeks of the war, like the sinking of three British armoured cruisers by U-9, changed opinions.

The UC-I program was relaunched on October 1914, as a rail-transportable coastal U-Boot with the design of heavily modified UB-I proposed by Germaniawerft on 15 October 1914. This eased R&D and enabled a speedy delivery. The final design was worked on and completed for acceptance by the admiralty, with Torpedo Inspectorate under the direction of Dr. Werner. It was accepted and ordered in small quantities, just fifteen, in November 23, 1914 with deliveries promised by Germaniawerft before the spring of 1915. UC-I was launched at Vulcan shipyard, Hamburg on April 26, 1915, commissioned on July 5, 1915 and started operations, which became extremely successful. UC-6 along sank 64.064 GRT, so 380 times her own tonnage.

Limitations of the UC-I design

However like for the UB-I, these small and inexpensive coastal boats were criticized in reports by captains as woefully under-sized for their missions. They had a single shaft and no redundancy, had a difficult balance for buoyancy, especially after dropping their mines, had no torpedoes, poor seaworthiness, especially in heavy weather, poor range, depth and speed, and carried only 12 mines in six tubes, preset at port, meaning if their minefield area changed, they needed to return to port to have them reset as it was impossible at sea. The UC-120 mines had a mooring depth adjustable up to roughly 100 meters (328 ft) of cable length, and if the first area could not be reached, captains had to return home or find a compatible area by depth. All this made clear for the Admiralstaff that a better model was needed. Oh the other hand, events also made possible more investments on this type when by the summer of 1916 restrictions were imposed on the unrestricted submarine warfare campaign. Mines in that context were more effective.

Design 41

UC-56

The UC-II development proper started around a simple idea of boosting power whatever the remainder of the design: The UC-I were so underpowered they were pushed around or unable to go against the strong currents of the English Channel as well as estuaries. To that, the Admiralstaff added the capability of operating in the Mediterranean. It was clear that neither Austria-Hungary or the Ottom Empire could contribute anything useful in the submarine warfare locally, so U-Boats were needed for this threater as well. A minelayer designed for Mediterranean Operations was thus considered, and both programs fusioned into a single new UC-II design.

They were designed also to carry the UC/200 mines in the same number of inclined mine shafts going through the pressure hull, however the latter was larger to accomodate two shafts and twice as much powerful machinery, so the hull being deeper, three mines could be installed per tube, making for a total of eighteen mines. More so, since the hull was also longer, there was now a torpedo room for three tubes, two external but reloadable, and one external at the stern not reloadable and defensive. The hull was larger and more stable, enabling also the intallation of a 8.8 cm gun and even later during the war a 10.5 cm gun, giving a lot of options to skippers. Endurance was doubled at up to month. All this was at the cost of sacrificing the ability to easily transport the vessels by rail, but it was seen worth it.

Construction challenges

On August 29, 1915, as part of the wartime fleet expansion program, Admiral Tirpitz decided to order the first series of UC II-class submarines, comprising 18 vessels (UC-16 through UC-33), with delivery scheduled for the first half of 1916. On November 20 of that year, an order was placed for a subsequent series of 21 vessels of this type (UC-34 – UC-48), and on January 11, 1916, the order was expanded to include additional units (UC-49 – UC-79). Of the 64 UC II-class vessels:
-24 were built at the Blohm & Voss shipyard in Hamburg
-21 at the Vulcan shipyard in Hamburg
-7 at the AG Weser shipyard in Bremen
-6 at Germaniawerft shipyard in Kiel
-6 at the Kaiserliche Werft in Danzig.
The UC-II or Project 41 had widly varying specifications due to brand new yards invited to tenders, not used to submarine contruction. “Pure players” were Germaniawerft in Kiel and Kaiserliche Werft in Danzig traditionally, to what were added AG Weser in Bremen, Blohm & Voss and Vulcan in Hamburg. It was their interpretation to the design that caused that many deviations. AG Weser also started building the U57 class from the late 1915. Vulcan also started to work with the U71 class by early 1915, Blohm & Voss worked in 1917 of the U-117 class or UE-II large minelaying submarines in additon to the UC-II and UC-III.

The keels were laid between 1915 and 1916, and the vessels were launched between 1916 and 1917. Depending on the shipyard, the construction cost per vessel ranged from 1.727 million to 2.141 million marks. Comprising 64 units, the UC II class was the second-largest series of submarines built in Germany during World War I, after the the UB III class. Their replacement, the excellent UC-IIIs, were started too late to see substantial service however.

Design of the class

Hull and general design

Plans for the UC-II, origin unknown. This is the late bow type.

The UC-II as seen above or UC-18 class were much larger boats as seen above, their displacement went from 400 to 434 t (394–427 long tons) surfaced and 480–511 t (472–503 long tons) submerged of 417 light and surfaced max, 493 tonnes submerged, light, and 545 tonnes submerged, fully loaded on other sources. This was for an overall length of 49.35 meters up to 53.15 meter (161 ft 11 in to 174 ft 5 in). Only the beam and draught were constant apparently as reported between yards, 5.22 m (17 ft 2 in) overall for the beam and 3.65 m (12 ft) in draught. The pressure hull measured on average 39,30 meters (129 feet) for a beam of 3,65 meters (12 feet). Total height from the keel up to the top of the CT was 7,46 meters or 24 feet 5 inches.

The outlook was very different from the UC-I as well. To address the issue of seakeeping when surfaced, with the small UC-I tossed around like toys in the short swell of the North Sea, always wet, the UC-II had a raised “forecastle” which was the best recoignition feature of the class, absent from the next UC-III. Like “toothbrush” style destroyers typical of Germany, they had a raised portion of the hull just in front of the 8.8 cm deck gun. This break was tall by about 50 cm, clearing out the barrel to fire at 0° ahead. This ended with a clipper prow wit rounded chin and rounded top nose, but between yards, the shape of the bow differed. This camel back also made the mine wells taller, without much changing draught, which had the other effect of raising their height, enabling an extra mine to be carried. The forward “forecastle” also was sloped upwards up to the stem.

There was also a change of bow shape: Because the class was ordered in multiple batches across different shipyards during World War I, variations in design emerged over their production run. The change in bow design was implemented primarily to improve the vessels’ hydrodynamic efficiency and seaworthiness.
The Early Rounded Bow in initial batches were built with a blunt, rounded nose (plans below). While functional for housing the forward vertical minelaying chutes and the external torpedo tubes, this profile created significant water resistance when traveling on the surface and caused the boats to ride roughly in heavy seas.
Later they received a Clipper Bow, a sharp, pointed nose, which in some variants. This design cut through waves much more efficiently, improving surface speed, stability, and overall handling.
The newer pointed bow design was so superior that the Imperial German Navy didn’t limit it strictly to new builds. Many earlier UC-II U-boats were brought into drydock and modified, receiving a replacement pointed bow structure post-construction to standardize their handling characteristics across the fleet. This pointed structural progression ultimately laid the design baseline for the succeeding Type UC-III.

Sources: https://virtualdockyard.co.uk/0-PLANS-PAGES/U-BOATS.html, origin unknown.

The torpedo tubes were external given their lenght and the bulk taken by the mine shafts. This was better than nothing, but unlike traditional torpedo tubes, since they were mounted externally besides the raised mineshaft deck, there was no way to reload them at sea, at least underwater. The tubes were encased in fairings, and their back had a hatch to access the tube bottom and proceeded to a reload at least on paper when surfaced. Indeed these submarines had seven torpedoes overall, with three pre-loaded in tubes before departing, this left four spares. This arrangement was forcing a very unusual storage system for its four reserve torpedoes: There were twi forward Spares externally just behind the tubes, tucked above the ballast tanks on the sides of the hull. They could only be reloaded into the tubes while the submarine was fully surfaced.

The crew had to open the outer casing and physically haul the heavy torpedoes forward into the tubes, a dangerous operation that required relatively calm seas. There two aft spares for the single stern torpedo tube. It was mounted internally but space at the back was incredibly restricted. The two aft spare torpedoes were stored internally in the tiny aft torpedo compartment. Since it was too small to house fully assembled reloads, these two spare torpedoes had to be disassembled into three separate parts for storage. If the crew needed to reload the stern tube, they had to manually piece the torpedo back together inside the cramped space before it could be loaded and fired. Not a popular task.

As for the rest of the design, the UC-II had a conventional double hull instead of a single hull with saddle tanks. The main hull was well rounded, in conformity to previous designs that evolved from the earlier style of flat topped hull, for better underwater penetration. The mine wells were still angled like the ones on the UC-I to control the drop. They were numbered six to one from rear to forward. The forward crew berthing compartment and gallery were located below the main gun, the control room was amidship, with the conning tower bell above, but it only housed the main navigation persicope, the smaller attack persicope was located in an extension forward, out of the bell, and likely retractable. The amidship control room was inclosed in convex and concave bulkheads. There were another set of berthing behind, followed by the engine room separated by a flat bulkhead housing in a single space both diesels and electric motors. Then came the aftermost crew’s quarters followed by the cramped aft torpedo compartment.

The two battery spaces were located under decks forward and aft. There were two deck hatches: The one forward was located just in front of the main gun. The one aft was located in the engine room. There was also the officer’s hatch located in the conning tower. The fairing of the “sail” was typically German, dispensing with an external helsman post, it was located below. There platform aft was surrounded by an arched fairing. The boats had wireless communication with a single mast aft of the CT. There was an optional net cutting gear at the nose on all boats, and a dual protecting cable ran from stern to prow, anchored on a small portico in the CT fairing which had an upper platform for observation.

As for diving planes, there were two sets, forward rounded and not folding, protected by guards bars and the same aft. The same guard bars aft also protected the two shafts and propellers. The latter ated as axis for these, their shape was squarish however. Some boats had no external anchors: There was a single axial one in a vertical well. There were extra guard bars to protect the external torpedo tubes heads as well. Most scoops were between the transition of the vertical outer deck hull and the main hull below. Some also had upper hull anti-colission aft guarbars, and there was another guard bar above the stern tube. There was a pair of rudders anchored on pillars. Some boats also had a reinforcement longitudinal bars, and there bollards and navigation lights on deck fore and aft, repeated ny upper navigation lights in recesses of the conning tower. The upper forward fairing had a repeater for manoeuvers, and was normally wrapped in canvas.

⚙ UC-II Dimensions Variations
Displacement UC16 – 24:	417 / 493
Displacement UC33,40 – 45:	400 / 480
Displacement UC34 – 39:	427 / 509
Displacement UC46 – 48:	420 / 502
Displacement UC49 – 54:	434 / 511
Displacement UC55 – 60:	415 / 498
Displacement UC61 – 64:	422 / 504
Displacement UC65 – 73:	427 / 508
Displacement UC74 – 79:	410 / 493
Dimensions UC16 – 33	40-45, 49.4m x 5.22 x 3.68m
Dimensions UC34 – 39, 65 – 73:	50.4 x 5.22 x 3.65m
Dimensions UC46 – 48, 61 – 64:	51.9 x 5.22 x 3.67m
Dimensions UC49 – 54:	52.7 m x 5.22x : 3.64
Dimensions UC55 – 60, 74 – 79:	50.5 x 5.22 x 3.61

Powerplant

There were variations between yards and industrial bottlenecks for the delivery of diesels here. Whatever the types, they had two shaft, two diesel engines rated between 490 and 590 horsepower, and two electric motors rated between 450 and 610 horsepower. The diesels were from MAN, Daimler, or Körting. The electric engines were either from Siemens Schukert (SSW) or Brown Boveri. This performances diverged also greatly, from 11.6 knots to 12 knots. The average was 11.7 knots surfaced. Submerged it also varied wildly, between 6.7 and 7.4 knots. Range also varied, because not all carried the same amount of diesel fuel, from 41 to 56 tonnes, making for a range between 7280 nautical miles surfaced to 10,420 all at 7 knots economical speed. Underwater, it ranged from 52 to 60 nautical miles at 4 knots. They could dive in all case at 50 meters (165 ft), their useful operational or service depth. It was likey around 75-80 m (260 ft) or more for the crush depth.

⚙ UC-II Powerplant Variations
Propulsion UC16 – 24, 34 – 39:	2 MAN diesels / 2 Brown Boveri electric motors
Propulsion UC25 – 27, 31 – 33, 46 – 48, 61 – 73:	2 MAN diesels / 2 SSW electric motors
Propulsion UC28 – 30, 76 – 79:	2 Daimler diesels / 2 SSW electric motors
Propulsion UC40 – 45, 74, 75:	2 Körting diesels / 2 SSW electric motors
Propulsion UC49, 50, 55 – 57:	2 Körting diesels / 2 Brown Boveri electric motors
Propulsion UC51 – 54, 58 – 60:	2 Daimler diesels / 2 Brown Boveri electric motors
Speed UC16-39:	11.6 or 11.9 / 7, 6.7 and 6.8 kts
Speed UC40 – 48:	11.7 / 6.7-6.9 kts
Speed UC49 – 54:	11.8 / 7.2 kts
Speed UC55 – 60:	11.6 / 7.3 kts
Speed UC61 – 64:	11.9 / 7.2 kts
Speed UC65 – 73:	12 / 7.4 kts
Speed UC74 – 79:	11.8 / 7.3 kts
Range UC16 – 24 (56t):	9,430nm at 7 kts / 55nm at 4 kts
Range UC25 – 27 (55t):	9,260nm at 7 kts / 53nm at 4 kts
Range UC28 – 30 (55t):	9,410nm at 7 kts / 53nm at 4 kts
Range UC31 – 33 (55t):	10,040nm at 7 kts / 53nm at 4 kts
Range UC34 – 39 (55t):	10,100nm at 7 kts / 54nm at 4 kts
Range UC40 – 45 (55t):	9,410nm at 7 kts / 60nm at 4 kts
Range UC46 – 48 (41t):	7,280nm at 7 kts / 54nm at 4 kts
Range UC49 – 54 (56t):	9,450nm at 7 kts / 56nm at 4 kts
Range UC55 – 60 (56t):	9,450nm at 7 kts / 52nm at 4 kts
Range UC61 – 64 (43t):	8,000nm at 7 kts / 59nm at 4 kts
Range UC65 – 73 (56t):	10,420nm at 7 kts / 52nm at 4 kts
Range UC74 – 79 (55t):	10230nm at 7 kts / 52nm at 4 kts

Armament

The primary armament of these boats were the six centerline 100-centimetre (39 in) mine shafts which contained three UC 120 mines each. This was completed by three torpedo tubes, all 50 cm, two external forward with spare torpedoes nearby, reloaded only when surfaced in calm weather, and one tube internal aft, with a small pressure hull compartment so it could be reloaded underwater, but the process was complicated as the torpedoes were in separated in parts and needed assembly in a tight space. They also had a 8.8 cm deck gun with 130 rounds, a great improvement over the UC-I, and a AA machine gun aft with a removable pintle. The 8.8 cm was later replaced by a 10.5 cm gun.

UC-200 Mines (primary)

The UC-200 was the standard naval sea mine deployed by the Imperial German Navy’s coastal minelaying submarines during World War I. Developed in mid-1915 with was the successor to the smaller UC-120, and became the primary payload for the highly successful Type UC II class. They were moored Hertz-horn contact mine, floating beneath the surface, anchored to the seabed by a mooring cable. Deployment from the UC-II started with the six internal mine chutes in wet storage, with the chutes located in the bow, completely open to the sea. They permanently submerged inside the tubes until dropped by gravity sequentially from the bottom of the chutes. Just as for the UC-I were were preset before departing for a specific operational area and could not reset. If the area was unreachable, the skipper had to find another compatible with these settings.

Specifications: Dimensions: 86 cm (34 inches) diameter.
Weight: Around 281 kg (620 lbs) total, including the mine and anchoring base.
Explosive Charge: Loaded with either 100 kg (220 lbs) of cast TNT (Type III variant) or 81.6 kg (180 lbs) of wet guncotton (Type IV variant).
Operational Depth: Ranging from 20 meters down to 100 meters.
Hertz horns—chemical-electrical impact fuzes protruding from the upper half with glass vial filled with acid. The released acid flowed into an internal battery component generating an electrical charge triggering the main detonator.

UC-120 Mines (alternative)

These UC-120 mines were moored contact naval models specifically designed the Type UC I submarine and Type UC II. They had a main explosive charge of approximately 120 kg (260–290 lbs) of wet guncotton or TNT. To detonate, they had chemical firing horns (acid-lead / Hertz horns). In Diameter they were 80 cm (31.5 in), built to fit standard 100 cm (39 in) vertical submarine mine chutes. Explosive Load was c120 kg (264–290 lbs) of wet guncotton or TNT. Mooring Depth was Adjustable up to roughly 100 meters (328 ft) of cable length. They were dropped via gravity from their vertical launch tubes via the bottom opening open to the sea. For survivor boats, they were replaced mid-1915 by the larger UC 200 mine and subsequent variations.

8.8 cm/27 TK L/30 C/08 deck gun

The 8.8 cm TK L/30 C/08 or “8.8 cm SK L/30” was the standard quick-firing naval deck gun until mid-war on U-boats. They came with 130 rounds. To minimize hydrodynamic drag and prevent water turbulence while the submarine was submerged, the weapon utilized a specialized mount configuration. Depending on the specific shipyard production batch of the UC-II class, the C/08 was installed on a pivot assembly that allowed the gun to be either lowered vertically or collapsed down flush against the deck structure before diving. UC-II submarines were structurally dense minelayers, the 8.8 cm deck gun was an indispensable asset for merchant raiding. According to Imperial German Navy doctrine, torpedoes and mines were expensive and strictly limited; the deck gun allowed a surfaced U-boat to halt merchant vessels, inspect their cargo, and sink them cheaply using high-explosive shells rather than wasting valuable underwater ordnance.

Mass: 644 kg (1,420 lbs) gun alone. Barrel Length 2.64 metres (8 ft 8 in).
Breech Mechanism: Krupp horizontal sliding-wedge design for swift manual chambering.
Rate of Fire: Up to 15 rounds per minute under optimal conditions with experienced crew.
Ammunition: Fixed, one-piece quick-firing shells weighing approximately 7 kg (15 lbs).
Maximum Range: Roughly 10,500 metres (11,500 yards) when fired from the specialized Ubts.L submarine pivot mount at max +30° elevation.

10.5 cm/42 Utof L/45 C/16 deck gun

The 8.8 cm started to be swapped for these in 1918 for those still around at the time. This was the standard deck gun on the Kaiserliches Marine at the time. The acronym Utof stands for “U-Boot-und-Torpedoboot-Flak” (Submarine and Torpedo Boat Anti-Aircraft gun), highlighting its multi-role capability. The designation translates to: 10.5 cm bore diameter / L/45 (barrel length of 45 calibres) / C/16 (Construktion 1916 blueprint model). For them, the decks needed to be reinforced. Plus the mount was low and barrel just barely cleared out the upper forward slope. The C/16 variant was meticulously designed to handle the brutal physical conditions of underwater deployment. The sight gears, dials, and several mechanical control linkages were manufactured entirely from high-grade brass to prevent rust and seizure from constant saltwater submersion. The High-Angle Elevation was a specialized U-Boot-Lafette (carriage) mount enabling up to +45°, at incoming Allied anti-submarine patrol aircraft. They likely then fired shotgun style AA HE rounds. They also had a provision of standard HE, illuminiation and AP rounds. However provision was less, probably c100.

Specs: Mass 1,450 kg (3,200 lbs) for the gun assembly itself.
Barrel Length: 4.725 metres (15 feet 6 inches).
Breech Mechanism: Horizontal sliding-wedge block.
Rate of Fire: 15 rounds per minute with an experienced deck crew.
Ammunition: Fixed, single-piece casing firing a massive 15.5 kg (34 lbs) high-explosive projectile.
Maximum Range: Up to 12,700 metres (13,900 yards) against surface targets.

0.3 (7.9mm)/79 AA Machine Gun

This was a liquid cooled MG 08 (Maschinengewehr 08), adapted into a specialized naval variant, 8 millimetres (0.31 in) machine gun to be brought up and fixed on a pintle with a supply of 150 rounds.
It was a belt-fed automatic weapon based on the Hiram Maxim 1884 patent. Ammunition: Fired standard 7.92×57mm Mauser rounds fed from 250-round fabric.

50 cm Torpedo Tubes

A said above, two forward external, one at the stern internal, two entire spare torpedoes in the outer hull aft, two dismounted in the compartment aft.
These were 50 cm (19.7-inch) G/6 if nothing esle was available or the better G7a:

G/6, G/6 K, KI, KII)

The G/6 was the workhorse, standard-issue German torpedo during the first half of World War I.
Propulsion: Powered by a wet-heater engine burning alcohol and compressed air.
Warhead: Contained a 160 kg (353 lbs) explosive charge.
Optimized for shorter ranges: 5 nautical miles (approx. 9,200 meters) at 27 knots.

G/7A (improved G/7)

They were installed when available. It’s understandable given their nature, UC boats were lower in priority compared to attack U-Boats. This design laid the direct technical blueprint for the famous G7a torpedoes used in WWII.
Propulsion: Utilized a more advanced “wet-heater” engine fueled by Decalin (decahydronaphthalene) and compressed air.
Warhead: Packed a heavier 195 kg (430 lbs) Hexanite explosive charge (a highly stable mixture of TNT and hexanitrodiphenylamine).
Considerably longer range and speed settings. 9,300 meters at 27 knots, or 37 knots at 4,000 meters.

Appearance

Old author’s rendition of a camouflaged UC-II.

The UC-II U-Boats were really impressive machines, and the most successful U-Boat types in WWI by Sheer Targets Destroyed. Indeed by the number of ships and tonnage sank overall, these were the Type VII of WW2. However individually, the U31 class was the most successful per individuak submarine. One was commanded by ace of aces Lothar Von Arneult the la Periere. However because their specialized UC-200 mines were laid invisibly in high-traffic shipping lanes, the 64 boats of the UC II class are estimated to have destroyed more than 1,800 vessels. Because many of their victims were smaller coastal freighters, fishing vessels, and minesweepers, their total overall tonnage is lower than that of the Type VII still.

The UC-II given their coastal nature were delivered in the standard two-tone grey livery ruled by the Imperial German Navy:
The Upper Hull & Conning Tower were painted in a bright light-grey (Hellgrau), intended to match coastal fog and overcast skies when cruising on the surface.
The Lower/Main Hull were coated in a darker iron-grey (Dunkelgrau) to help mask the bulk of the ship against dark seawater.
The Underwater Body was coated below the waterline in a dark red anti-fouling paint.
The slotted wooden or metal deck plating was typically covered in a dark black pitch or anti-corrosive coating to eliminate glint and reflections.
However from 1917 they started to be painted with an experimental splinter camouflage by the late War in 1917–1918. Indeed it was estimated the uniform light grey conning tower became too visible from above. Many active UC-II boats in the North Sea and English Channel sported localized camouflage patterns directly over their factory finishes. To blend with muddy, churning coastal waters, crews used patches of light grey, dark slate grey, and muddy brown/olive green. They utilized hard-edged geometric “splinter” blocks or undulating wave patterns. This was designed to break up the harsh, recognizable hard lines of the conning tower and the long horizontal plane of the hull casing, making it difficult for an enemy ship’s lookout or an airplane pilot to identify the submarine’s exact heading or speed.

They also wore Aerial Recognition Markings to avoid friendly bombing from the Navy’s own zeppelins and early biplanes. The tops of the conning towers on UC-II boats were often painted jet black or featured large, bold white identification numbers or symbols that could be easily seen from directly above. The CT canvas were also painted over with various scheme of camouflage or dark grey, but numbers and large markings became rare.

⚙ UC-II specifications
Displacement	400–434 t surfaced, 480–511 t submerged
Dimensions	49.35–53.15 m x 5.22 x 3.65m (161 ft 11 in–174 ft 5 in x 17 ft 2 in x 12 ft)
Propulsion	2 shafts 6-cyl. diesels 490–650 shp, 2 EM 340–460 kW
Speed	11.6–12 knots surfaced, 6.7–7.4 knots submerged
Range	7,280–10,040 mi (11,720–16,160 km) at 7 knots surfaced, 52–60 mi (84–97 km) at 4 knots submerged
Armament	3x 50cm TTs (7), 1x 8.8cm, 18x UC 120 mines, see notes
Max depth	50 m (160 ft)
Crew	3 officers, 23 ratings

Assessment

The combination of mines, torpedo and deck gun plus the extended range, better seaworthiness and increased surface speed made them most efficient of all designs. Still they had some drawbacks: The raised forecastle made them more difficult to handle, especially when wind was above Force 5. The raised bow made diving slower as well, and they still needed 35-40 second in diving time, which was higher than some larger boats. The third issue with the raised bow, which was supposed to protect the deck gun, in certain sea condition made it awash instead, especially in rough seas. Sea spray also made watchkeeping on the conning tower difficult even in moderate seas. The “invention” of CT breawater came later with the Type UC III as well as a flush hull and in general more streamlining overall. Four boats were lost in accidents, four were scuttled after the fall of Austria-Hungary, and UC61 grounded and scuttled in operations.

Career of the UC-II

UC-16 was laid down as yard number 266 at Blohm & Voss, Hamburg in 1915, launched on 1 February 1916 and commissioned on 26 June 1916. She was assigned to the Flandern I Flotilla from 11 September 1916 to 4 October 1917. She trained prior to that with Oblt.z.S. Egon von Werner from commission to 22 April 1917. She then was under orders from Oblt.z.S. Georg Reimarus until 4 October and made 13 patrols sinking 43 merchant ships (43,914 GRT), 4 damaged (24,465 GRT) and 2 auxiliary warships, some by mines, others by torpedo. On 23 September 1916 alone, in her first patrol, she sank the British trawler Andromeda (149t), the Beechwold (129t), the Britannia III (138t), Cockatrice (115t), Mercury (183t), Phoenix (117t), Refino (182t), Rego (176t), Restless (125t), Viella (144t), Weelsby (122t). In her second patrol on 19 October 1916 she sank the liner Alaunia (13,405 GRT) and on 22 October the Dutch Fortuna (1,254 GRT). On 11 November she clmaimled the Norwegian Daphne (1,388 GRT) and small British vessel Veronica (27t). Two days later on 13 November she wasnk the French trawler Marie Therese (156t). On 14 November her minefield sank the N.D. De Bon Secours France (81t), Nominoe (327t) and Salangane (125t). Two days later this was the French trawler Lelia (79t) and British merchant freighter Vasco (1,914 GRT). On the 26th she damaged the Norwegian merchant Caloric (7,012 GRT) and on the 28th the British Suffolk (7,573 GRT). On 30 December she damaged the British merchant Aspenleaf (7,535 GRT).

On 18 January 1917 she sank the Italian Merchant Taormina (2,457 GRT) and on the 19th, the Nowegian Anna (1,237 GRT), Reinunga(1,147 GRT), and Theresdal (1,762 GRT). On the 21st, she sank the French Trawler Couronne (169t). A day later she damaged the Dutch Juno (2,345 GRT) and on the 23rd, the Norwegian Ymer (1,123 GRT). Next patrol, on 15 February 1917 she sank the British “Leven” (775t) and on 26 February the British trawler Sea Gull (144t) and damaged the auxiliary trawler armed HMT St. Germain (307t). A month later on 15 March she sank the Coonagh (1,412 GRT) and on 20 April 1917 damaged the patrol ship HMS Glen (122t). On 27 July 1917 she claimed the same day the Dutch Dirk (81t), Dirk van Duyne (116t), Jan (104t), Majoor Thomson (110t), President Commissaris van den Burg (111t), Sterna III (111t) and a day later the Neptunus I (80t). On 16 August 1917 she sank the British merchant ship Manchester Engineer (4,465 GRT) and a day later the small trawler Susie (41t). Two days later on the 18th she sank the 1,274 GRT Ardens. On 4 September she sank the Bishopston (2,513 GRT) and on the 7th the British Hinemoa (2,283 GRT) and Norwegian Vestfjeld (2,063 GRT). Fate: Possibly sunk by a mine off Zeebrugge on 4 October 1917.

UC-17 was laid down as yard number 267 at Blohm & Voss, Hamburg in 1915, launched on 19 February 1916 and commissioned on 23 July 1916 Surrendered on 26 November 1918. Scrapped 1919-1920 at Preston.
To be updated in the future.

UC-18 was laid down as yard number 268 at Blohm & Voss, Hamburg in 1915, launched on 4 March 1916 and commissioned on 15 August 1916 Sunk in the English Channel by gunfire from British Q-ship HMS Lady Olive on 19 February 1917. To be updated in the future.

UC-19 was laid down as yard number 269 at Blohm & Voss, Hamburg in 1915, launched on 15 March 1916 and commissioned on 22 August 1916. She was depth-charged in the English Channel by HMS Landrail on 6 December 1916. To be updated in the future.

UC-20 was laid down as yard number 270 at Blohm & Voss, Hamburg in 1915, launched on 1 April 1916, and commissioned on 8 September 1916. Surrendered on 19 January 1919. Scrapped 1919-1920 at Preston. To be updated in the future.

UC-21 was laid down as yard number 271 at Blohm & Voss, Hamburg in 1915, launched on 1 April 1916, and commissioned on 15 September 1916. She was missing after 13 September 1917. To be updated in the future.

UC22 was laid down as yard number 272 at Blohm & Voss, Hamburg, in 1915, launched on 1 February 1916 and commissioned on 1 July 1916. Surrendered to France on 3 February 1919. Scrapped in July 1921 at Landerneau. To be updated in the future.

UC23 was laid down as yard number 273 at Blohm & Voss, Hamburg, in 1915, launched on 19 February 1916 and commissioned on 28 July 1916. Surrendered at Sevastopol on 14 November 1918. Scrapped in August 1921 at Bizerta. To be updated in the future.

UC-24 was laid down as yard number 274 at Blohm & Voss, Hamburg, in 1915, launched on 4 March 1916 and commissioned on 17 August 1916. Torpedoed and sunk by French submarine Circé off Cattaro (now Kotor) on 24 May 1917. Wreck found in late 2019. To be updated in the future.

UC-25 was laid down as yard number 64 at Vulcan, Hamburg in 1915, launched on 10 June 1916 and commissioned on 28 June 1916. Scuttled on 29 October 1918 off Pola when Austria-Hungary surrendered. To be updated in the future.

UC-26 was laid down as yard number 65 at Vulcan, Hamburg in 1915, launched on 22 June 1916, and commissioned on 18 July 1916. Rammed and sunk off Calais by HMS Milne on 9 May 1917. To be updated in the future.

UC-27 was laid down as yard number 66 at Vulcan, Hamburg in 1915 launched on 28 June 1916 and commissioned on 25 July 1916. She surrendered to France on 3 February 1919. Scrapped in July 1921 at Landerneau. To be updated in the future.

UC-28 was laid down as yard number 67 at Vulcan, Hamburg in 1915, launched on 8 July 1916, and commissioned on 6 August 1916. Surrendered to France on 12 February 1919 and later scrapped. To be updated in the future.

UC-29 was laid down as yard number 68 at Vulcan, Hamburg in 1915, launched 15 July 1916, and commissioned on on 15 August 1916. Ambushed and sunk by Q-ship HMS Pargust off the Irish coast on 7 June 1917. To be updated in the future.

UC-30 was laid down as yard number 69 at Vulcan, Hamburg in 1915, launched 27 July 1916, and commissioned on 22 August 1916. Sunk by a mine off Horns Reef on 21 April 1917. To be updated in the future.

UC-31 was laid down as yard number 70 at Vulcan, Hamburg, in 1915, launched in August 1916 and commissioned on 2 September 1916. Surrendered on 26 November 1918 and scrapped in 1922 at Canning Town. To be updated in the future.

UC-32 was laid down as yard number 71 at Vulcan, Hamburg, in 1915, launched on 12 August 1916 and commissioned on 13 September 1916. Sunk by its own mine on 23 February 1917. To be updated in the future.

UC-33 was laid down as yard number 72 at Vulcan, Hamburg, in 1915, launched on 26 August 1916 and commissioned on 25 September 1916. Shelled, rammed and sunk in St. George’s Channel by patrol boat PC61 on 24 May 1917. To be updated in the future.

UC-34 was laid down as yard number 275 at Blohm & Voss, Hamburg, in 1915, launched on 6 May 1916 and commissioned on 26 September 1916. Scuttled on 30 October 1918 off Pola when Austria-Hungary surrendered. To be updated in the future.

UC-35 was laid down as yard number 276 at Blohm & Voss, Hamburg, in 1915, launched on 6 May 1916 and commissioned on 4 October 1916. Sunk off South Sardinia by gunfire from French naval trawler Ailly on 16 May 1918. To be updated in the future.

UC-36 was laid down as yard number 277 at Blohm & Voss, Hamburg, in 1915, launched on 25 June 1916 and commissioned on 3 November 1916. Rammed and sunk by French steamer Molière off Ushant on 21 May 1917. To be updated in the future.

UC-37 was laid down as yard number 278 at Blohm & Voss, Hamburg, in 1915, launched on 5 June 1916 and commissioned on 13 October 1916. Surrendered at Sevastopol on 25 November 1918. Scrapped in August 1921 at Bizerta. To be updated in the future.

UC-38 was laid down as yard number 279 at Blohm & Voss, Hamburg, in 1915, launched on 5 June 1916 and commissioned on 19 October 1916. Depth-charged by French destroyers in the Gulf of Corinth on 14 December 1917. To be updated in the future.

UC-39 was laid down as yard number 275 at Blohm & Voss, Hamburg, in 1915, launched on 25 June 1916 and commissioned on 29 October 1915. Sunk off Flamborough Head by gunfire from HMS Thrasher on 8 February 1917. To be updated in the future.

UC40 was laid down as yard number 73 at Vulcan, Hamburg, in 1915, launched on 5 Sept. 1916 and commissioned on 10.1916. Lost on transfer to United Kingdom 21.1.1919. To be updated in the future.

UC41 was laid down as yard number 74 at Vulcan, Hamburg, in 1915, launched on 13.9.1916 and commissioned on 10.1916. Sunk 21 August 1917: Depth-charged by British naval trawlers in the Tay estuary following an explosion of one of its own mines. To be updated in the future.

UC42 was laid down as yard number 75 at Vulcan, Hamburg, in 1915, launched on 21.9.1916 and commissioned on 11.1916. Sunk by its own mine off the Irish coast on 10 September 1917. To be updated in the future.

UC43 was laid down as yard number 76 at Vulcan, Hamburg, in 1915, launched on 5.10.1916 and commissioned on 10.1916. Torpedoed and sunk by HMS G13 north of Muckle Flugga on 10 March 1917. To be updated in the future.

UC44 was laid down as yard number 77 at Vulcan, Hamburg, in 1915, launched on 10.10.1916 and commissioned on 11.1916. Sunk by its one of its own mines on 4 August 1917 off the Irish coast. Raised by the Royal Navy a month later and later scrapped. To be updated in the future.

UC45 was laid down as yard number 78 at Vulcan, Hamburg, in 1915, launched on 20.10.1916 and commissioned on 11.1916. Sank in a diving accident in the North Sea on 17 September 1917. Raised and surrendered in 1918. Scrapped in 1920 at Preston. To be updated in the future.

UC46 was laid down as yard number 256 at Weser, Bremen, in 1915, launched on 15.7.1916 and commissioned on 9.1916. Sunk 8.2.1917: Rammed by HMS Liberty southeast of Goodwin Sands. To be updated in the future.

UC47 was laid down as yard number 257 at Weser, Bremen, in 1915, launched on 30.8.1916 and commissioned on 10.1916. Rammed and depth-charged by British patrol boat P-57 off Flamborough Head on 18 November 1917. To be updated in the future.

UC48 was laid down as yard number 258 at Weser, Bremen, in 1915, launched on 27.9.1916 and commissioned on 11.1916. Interned at Ferrol, Spain from 20 March 1918. To be updated in the future.

UC49 was laid down as yard number 265 at Germaniawerft, Kiel, in 1916, launched on 7.11.1916 and commissioned on 12.1916. Sunk by a mine off Flanders on 14 August 1918. To be updated in the future.

UC50 was laid down as yard number 266 at Germaniawerft, Kiel, in 1916, launched on 23.11.1916 and commissioned on 12.1916. Missing after 7 January 1918. To be updated in the future.

UC51 was laid down as yard number 267 at Germaniawerft, Kiel, in 1916, launched on 5.12.1916 and commissioned on 1.1917. Sunk by a mine in the English Channel on 17 November 1917. To be updated in the future.

UC52 was laid down as yard number 268 at Germaniawerft, Kiel, in 1916, launched on 23.1.1917 and commissioned on 3.1917. Surrendered on 16 January 1919. Scrapped in 1920 at Morecambe. To be updated in the future.

UC53 was laid down as yard number 269 at Germaniawerft, Kiel, in 1916, launched on 27.2.1917 and commissioned on 4.1917. Scuttled on 28 October 1918 at Pola when Austria-Hungary surrendered. To be updated in the future.

UC54 was laid down as yard number 270 at Germaniawerft, Kiel, in 1916, launched on 20.3.1917 and commissioned on 5.1917. Scuttled on 28 October 1918 at Trieste when Austria-Hungary surrendered. To be updated in the future.

UC55 was laid down as yard number 37 at KW Danzig, in 1916, launched on 2.8.1916 and commissioned on 11.1916. Sank in diving accident off the Shetland Islands on 29 September 1917. To be updated in the future.

UC56 was laid down as yard number 38 at KW Danzig in 1916, launched on 26.8.1916 and commissioned on 12.1916. Interned at Santander, Spain from 24 May 1918. To be updated in the future.

UC57 was laid down as yard number 39 at KW Danzig in 1916, launched on 7.9.1916 and commissioned on 1.1917. Missing after 18 November 1917. Probably sunk by a mine in the Gulf of Finland. To be updated in the future.

UC58 was laid down as yard number 40 at KW Danzig in 1916, launched on 21.10.1916 and commissioned on 3.1917. Surrendered on 24 November 1918. Scrapped in 1921 in Cherbourg. To be updated in the future.

UC59 was laid down as yard number 41 at KW Danzig in 1916, launched on 28.9.1916 and commissioned on 5.1917. Surrendered on 21 November 1918. Scrapped 1919-20 in Bo’ness.

UC60 was laid down as yard number 42 at KW Danzig in 1916, launched on 8.11.1916 and commissioned on 6.1917. Surrendered on 23 February 1919. Scrapped in 1921 at Rainham. To be updated in the future.

UC61 was laid down as yard number 259 at Weser, Bremen in 1916, launched on 11.11.1916 and commissioned on 12.1916. Stranded at Wissant on 26 July 1917 and scuttled. To be updated in the future.

UC62 was laid down as yard number 260 at Weser, Bremen in 1916, launched on 9.12.1916 and commissioned on 1.1917. Sunk by a mine off Zeebrugge on 14 October 1917. To be updated in the future.

UC63 was laid down as yard number 261 at Weser, Bremen in 1916, launched on 6.1.1917 and commissioned on 1.1917. Torpedoed and sunk by HMS E52 off Goodwin Sands on 1 November 1917. To be updated in the future.

UC64 was laid down as yard number 262 at Weser, Bremen in 1916, launched on 27.1.1917 and commissioned on 2.1917. Sunk by a mine in the Dover Strait on 20 June 1918. To be updated in the future.

UC65 was laid down as yard number 281 at Blohm & Voss, Hamburg in 1916, launched on 8.7.1916 and commissioned on 11.1916. Torpedoed and sunk in the English Channel by HMS C15 on 3 November 1917. To be updated in the future.

UC66 was laid down as yard number 282 at Blohm & Voss, Hamburg in 1916, launched on 15.7.1916 and commissioned on 11.1916. Sunk in an attack by HM seaplane No. 8656 off the Icles of Scilly on 27 May 1917. Wreck found in 2009. To be updated in the future.

UC67 was laid down as yard number 283 at Blohm & Voss, Hamburg in 1916, launched on 6.8.1916 and commissioned on 12.1916. Surrendered on 16 January 1919. Scrapped in 1919-20 at Briton Ferry. To be updated in the future.

UC68 was laid down as yard number 284 at Blohm & Voss, Hamburg in 1916, launched on 12.8.1916 and commissioned on 12.1916. Lost to unknown cause off The Lizard on 13 March 1917. To be updated in the future.

UC69 was laid down as yard number 285 at Blohm & Voss, Hamburg in 1916, launched on 7.8.1916 and commissioned on 12.1916. Accidentally rammed and sunk near Barfleur by U-96 on 6 December 1917. Wreck found by accident in November 2017. To be updated in the future.

UC70 was laid down as yard number 286 at Blohm & Voss, Hamburg in 1916, launched on 7.8.1916 and commissioned on 11.1916. Depth-charged off the eastern English coast by HMS Ouse on 28 August 1918. The wreck has since been declared a war grave. To be updated in the future.

UC71 was laid down as yard number 287 at Blohm & Voss, Hamburg in 1916, launched on 12.8.1916 and commissioned on 11.1916. Lost on transfer to United Kingdom 20 Feb. 1919. To be updated in the future.

UC-72 was laid down as yard number 288 in 1916, launched on 12 August 1916 and commissioned on 5 December 1916. She was sunk by a mine in the Straits of Dover sometime after 24 August 1917. To be updated in the future.

UC73 was laid down as yard number 289 at Blohm & Voss, Hamburg in 1916, launched on 26.8.1916 and commissioned on 12.1916. Sunk by a mine in the Straits of Dover sometime after 24 August 1917. To be updated in the future.

UC74 was laid down as yard number 79 at Vulcan, Hamburg in 1916, launched on 19.10.1916 and commissioned on 11.1916. Surrendered on 6 January 1919. Scrapped 1919-1920 at Briton Ferry. To be updated in the future.

UC75 was laid down as yard number 80 at Vulcan, Hamburg in 1916, launched on 6.11.1916 and commissioned on 12.1916. Interned at Barcelona on 21 November 1918 when she ran out of fuel. Surrendered to France on 26 March 1919. Scrapped in July 1921 at Toulon. To be updated in the future.

UC76 was laid down as yard number 81 at Vulcan, Hamburg in 1916, launched on 25.11.1916 and commissioned 17 December 1916. Rammed and sunk in the North Sea by HMS Fairy on 31 May 1918. To be updated in the future.

UC77 was laid down as yard number 82 at Vulcan, Hamburg in 1916, launched on 2.12.1916 and commissioned in December 1916. Surrendered on 1 December 1918. Scrapped 1919-1920 at Briton Ferry. To be updated in the future.

UC78 was laid down as yard number 83 at Vulcan, Hamburg in 1916, launched on 8.12.1916 and commissioned on 29 December 1916. Sunk by a mine off Flanders on 11 July 1918. To be updated in the future.

UC79 was laid down as yard number 85 at Vulcan, Hamburg in 1916, launched on 19 Dec. 1916 and commissioned on 22 January 1917. Rammed and sunk off Cherbourg by British steamer Queen Alexandra on 9 May 1918. To be updated in the future.

Gallery

Read More/Src

Books

Breyer, Siegfried (1992). Soviet Warship Development: Volume 1: 1917–1937. London: Conway Maritime Press.
Gröner, Erich; Jung, Dieter; Maass, Martin (1991). German Warships 1815–1945, U-boats and Mine Warfare Vessels. Vol. 2. Conway Maritime Press.
Herzog, Bodo (1993). Deutsche U-Boote : 1906 – 1966 [German U-boats : 1906 – 1966] (in German). Erlangen: Müller.
Messimer, Dwight R. (2002). Verschollen : World War I U-boat losses. Annapolis: Naval Institute Press.
Möller, Eberhard; Brack, Werner (2004). The Encyclopedia of U-Boats. London: Chatham.
Rössler, Eberhard (1981). The U-boat: The evolution and technical history of German submarines. London: Cassell & Co.
Termote, Tomas (2014). Oorlog onder Water, Unterseeboots Flottille Flandern 1915–1918. Davidsfonds.
Terraine, J. (1999). Business in Great Waters: The U-boat Wars, 1916–1945. London: Leo Cooper.

Links

wrecksite.eu
Reloading the forward tubes – facebook
jerijerod14.substack.com
westernfrontassociation.com
sakhalianet.x10.mx
ww1-u-boat-types
navypedia.org/
uboat.net/
dreadnoughtproject.org
en.wikipedia.org UC-II
pl.wikipedia.org/
commons.wikimedia.org
UC-61 grounded gallery
commons.wikimedia.org

Videos

Model Kits

on scalemates.com/
pn modellmarine.de/