German Type UB I submarine

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SM UB-1 seen after her sale to the Austro-Hungarian Navy for service as SM U-10
Class overview
Builders:	Germaniawerft, Kiel (8)[1] AG Weser, Bremen (12)
Operators:	German Imperial Navy[2]  Austro-Hungarian Navy[3]  Bulgarian Navy[4]
Built:	1914–1915
In commission:	1915–1918
Completed:	20
Lost:	10[3][5]
Scrapped:	10[2][3][4]
General characteristics
Type:	coastal submarine
Displacement:	127 tonnes (140 short tons), surfaced[1] 142 tonnes (157 short tons), submerged
Length:	92 ft 2 in (28.1 m), UB-1–UB-8[2] 91 ft 6 in (27.9 m)[2]
Beam:	10 ft 6 in (3.2 m)[2]
Height:	7.3 m (24 ft)[6]
Draught:	9 ft 10 in (3.0 m)[2]
Propulsion:	1 × propeller shaft 1 × Daimler (UB-1–UB-8) or Körting 4-cylinder diesel engine, 60 bhp (45 kW)[2] 1 × electric motor, 120 shp (89 kW)[2]
Speed:	6.47 knots (11.98 km/h), surfaced[1] 5.51 knots (10.20 km/h), submerged
Endurance:	1,650 nautical miles @ 5 knots, surfaced (3,060 km @ 9.3 km/h)[2] 45 nautical miles @ 4 knots, submerged (83 km @ 7.4 km/h)[2]
Test depth:	50 metres (160 ft)[2]
Complement:	14[2]
Armament:	2 × 45 cm (17.7 in) bow torpedo tubes[2] 2 × torpedoes 1 × 8 mm (0.31 in) machine gun
Notes:	33-second diving time[2]

The Type UB I was a class of small coastal submarines or U-boats built in Germany during the early part of World War I. A total of twenty boats were built, with the majority in the service of the German Imperial Navy (German: Kaiserliche Marine). Boats of the design were also operated by the Austro-Hungarian Navy (German: Kaiserliche und Königliche Kriegsmarine or K.u.K. Kriegsmarine) and the Bulgarian Navy. The class is sometimes also referred to as the UB-1 class after SM UB-1, the class leader. In the Austro-Hungarian Navy, the class was called the U-10 class.

These submarines were built in response to a need for small, maneuverable boats that could operate in the narrow, shallow seas off Flanders. They were intended to be quickly built, shipped by railroad, and assembled at their port of operation. The design effort began in mid-August 1914 and the first fifteen boats were ordered in mid-October from two German shipyards. The German Imperial Navy ordered an additional pair later to replace two boats sold to Austria-Hungary, which ordered a further three in April 1915. The total number of UB I boats constructed was twenty. Production on the first boats for Germany began in early November 1914; all twenty had been completed by October 1915.

Several of the first boats underwent trials in German home waters, but the rest of the boats were assembled and tested at either Antwerp or Pola. The German boats operated primarily in the Flanders, Baltic, and Constantinople Flotillas. There were small size variations between boats from the two manufacturers, with the boats being about 92 feet (28 m) long and displacing between 127 and 142 tonnes (140 and 157 short tons). All had two torpedo tubes armed with two torpedoes, and were equipped with a deck-mounted machine gun.

In 1918, four of the surviving German boats were made into coastal minelayers. Of the seventeen boats in German service, two were sold to Austria-Hungary, one was sold to Bulgaria, and nine were lost during the war. One of the five Austro-Hungarian boats was sunk and another mined and not repaired. The five surviving German boats, the four surviving Austro-Hungarian boats, and the Bulgarian boat were all turned over to the Allies after the end of the war and were broken up.

[edit] Design

In the earliest stages of World War I, the German Army's rapid advance along the North Sea coast found the German Imperial Navy without submarines suitable to operate in the narrow and shallow seas off Flanders.^[7][8] By 18 August, just two weeks after the German invasion of Belgium, the planning of a series of small, coastal submarines had already begun.^[8]

The German Imperial Navy stipulated that the submarines be transportable by rail, which imposed a maximum diameter of 10 feet 4 inches (3.1 m)—the largest size transportable via rail—for the boats. The rushed planning effort^[7]—which had been assigned the name "Project 34"—resulted in the Type UB I design, created specifically for operation from Flanders. The boats, essentially submersible torpedo boats, were to be about 92 feet (28 m) long and to displace about 125 tonnes (138 short tons) with two torpedo tubes.^{[7][Note 1]}

One of the minor differences in the Type UB I boats was the number and size of vents in the upper casing. The vents on the Germaniawerft-built UB-2 (left) are larger than those on UB-16, built by AG Weser.

Boats of the UB I design were built by two manufacturers, Germaniawerft of Kiel and AG Weser of Bremen,^[9] which led to some variations in boats from the two shipyards. The eight Germaniawerft-built boats were slightly longer at 92 feet 2 inches (28.1 m) (oa), while the twelve Weser-built boats came in 8 inches (20 cm) shorter. All were 10 feet 6 inches (3.2 m) abeam and had a draft of 9 feet 10 inches (3.0 m).^[2] The boats all displaced 127 tonnes (140 short tons) while surfaced but had slightly different underwater displacement figures. The slightly longer Germaniawerft boats displaced 142 tonnes (157 short tons) while submerged, weighing 1 tonne (1.1 short tons) more than the Weser boats.^[1] There were other mostly cosmetic differences among the boats, the major one being the number and size of vents in the upper casing; the Germaniawerft boats seem to have had a fewer number of larger vents, while the Weser boats had more, smaller vents.^[10]

The drivetrain of the boats consisted of a single propeller shaft driven by a Daimler (Germaniawerft) or Körting (Weser) diesel engine on the surface, or a Siemens-Schuckert electric motor for underwater travel.^[7] The Weser boats were capable of nearly 7.5 knots (13.9 km/h) on the surface and a little more than 6 knots (11 km/h) submerged. The Germaniawerft boats were about 1 knot (1.9 km/h) slower than their Bremen-made counterparts.^[1] The boats were equipped with two 45-centimetre (17.7 in) bow torpedo tubes and carried two torpedoes.^[2] They were also armed with a single 8-millimetre (0.31 in) machine gun affixed to the deck.^[8]

[edit] Construction

The German Imperial Navy ordered its first fifteen UB I boats on 15 October 1914.^[7][8] Eight boats—numbered UB-1 to UB-8—were ordered from Germaniawerft of Kiel,^[7][9] and seven boats—numbered UB-9 to UB-15—from AG Weser of Bremen.^[9] After two of the class, UB-1 and UB-15, were sold in February 1915 to ally Austria-Hungary (becoming U-10 and U-11 in that country's navy)^[11] the German Imperial Navy ordered UB-16 and UB-17 from Weser.^[7] A further three for Austria-Hungary —U-15, U-16, and U-17—had been ordered from Weser by April, bringing the total number constructed to twenty.^{[11][Note 2]}

UB-1 and UB-2 were laid down on 1 November 1914 at the Germaniawerft yard at Kiel.^[12][13] UB-1 was launched on 22 January 1915,^[12] just 75 working days later.^[9] UB-2's launch followed on 13 February.^[13] Among the Weser boats, UB-9 was laid down first, on 6 November 1914, and launched on 6 February 1915,^[14] a week ahead of UB-2. These first three boats launched underwent trials in German home waters, but all of the other members of the class were shipped via rail and underwent trials at their assembly point.^[15]

Sections of SM UB-13 on board railroad flatcars for transport to Antwerp, c. March 1915.

The process of shipping the submarines by rail involved breaking the submarine down into what was essentially a knock down kit. Each boat was broken into approximately fifteen pieces and loaded on to eight railway flatcars. UB I boats destined for service with the Flanders Flotilla (German: U-boote des Marinekorps U-Flotille Flandern) made a five-day journey to Antwerp for the 2- to 3-week assembly process. After assembly at Antwerp the boats were towed by barge to Bruges for trials.^[15] Boats selected for service in the Mediterranean were sent to the Austro-Hungarian port of Pola, where the assembly process took place.^[16] The total time from departure of the railcars from the shipyard to operational readiness for the boats was about six weeks.^[15]

By July 1915, all seventeen of the German Imperial Navy UB I boats had been completed.^[17] The three additional Weser boats for the Austro-Hungarian Navy were finished by October 1915.^[18]

[edit] Service

During their trials, the UB I boats were found to be too small and too slow,^[19] and had a reputation for being underpowered;^[20] one commander compared his UB I boat to a "sewing machine".^[20] According to authors R. H. Gibson and Maurice Prendergast in their 1931 book The German Submarine War, 1914–1918, the UB boats did not have enough power to chase down steamers while surfaced, and they lacked the stamina to spend any extended amount of time underwater, exhausting their batteries after little over an hour's running.^[20] In-service use revealed another problem: with a single propeller shaft/engine combination, if either component failed, the U-boat became almost totally disabled.^{[19][Note 3]}

But despite the problems, the "tin tadpoles"—as the Germans referred to them—were in active service from March 1915 through the end of the war,^[21] with half of the twenty boats lost during the war.^[3][5] Boats of the class served in three navies: the German Imperial Navy, the Austro-Hungarian Navy, and the Bulgarian Navy.^[2] In German service, they served primarily in the Flanders Flotilla, the Baltic Flotilla, and the Constantinople Flotilla.^[21]

[edit] German Imperial Navy

[edit] Flanders Flotilla

The first UB boat to begin active service was UB-10,^[20] which formed the nucleus of the Flanders Flotilla on 27 March 1915.^[15][22] By the end of April, five more UB I boats had become operational.^[23] UB-10 was eventually joined in the Flanders Flotilla by UB-2, UB-4, UB-5, UB-6, UB-12, UB-13, UB-16, and UB-17;^[24] of these, only UB-2 made the journey to Flanders by sea rather than rail.^[15]

UB-4 departed on the first patrol from Flanders on 9 April,^[25] and was responsible for sinking the first ship sent down by the flotilla.^[26] The UB I boats of the Flanders Flotilla originally patrolled the area between the United Kingdom and the Netherlands,^[25] but began patrolling the English Channel after UB-6 pioneered a route past British antisubmarine nets and mines in the Straits of Dover in late June.^[27]

Over the UB I boats' first year of service, UB-4 and UB-13 were both lost,^[28] and UB-2 and UB-5 were transferred to the Baltic Flotilla.^[29] In March 1917, UB-6 ran aground in Dutch waters and, along with her crew, was interned for the rest of the war.^[30] The four remaining UB Is in Flanders—UB-10, UB-12, UB-16, UB-17—were all converted to minelayers by 1918, having their torpedo tubes removed and replaced with chutes to carry up to eight mines.^[2] All but UB-10 were lost in 1918;^[31] UB-10, in poor repair and out of service, was scuttled in October 1918 when the Germans evacuated from Flanders.^[30]

[edit] Baltic Flotilla

UB-9 was initially assigned to the Baltic Flotilla (German: U-boote der Ostseetreitträfte V. U-Halbflotille), and joined by UB-2 and UB-5 in early 1916. All three became training boats at Kiel in 1916,^[29] joining UB-11 in that duty.^[32] Little information is available about the UB I boats operating in the Baltic.

[edit] Constantinople Flotilla

Four of the German Imperial Navy boats—UB-3, UB-7, UB-8, and UB-14—were selected for service with the Constantinople Flotilla (German: U-boote der Mittelmeer division in Konstantinopel). Initial plans called for them to be shipped by rail to the Stenia Yard in Constantinople, but incompatible rail gauges and tunnels too small for the loaded railcars prevented this.^[10] All were instead sent to Pola for assembly and trials there as part of the Pola Flotiila (German: Deutsche U-Halbflotille Pola), before sailing on to join the Constantinople Flotilla. UB-3 disappeared en route to Constantinople in May 1915,^[16] but the other three all arrived there by mid-June.^[24]

The three UB I boats of the Constantinople Flotilla seem to have patrolled primarily in the Black Sea. UB-8 was transferred to the Bulgarian Navy in May 1916,^[33] and UB-7 disappeared in the Black Sea in October 1916,^[34] leaving UB-14 as the sole remaining German UB I in the flotilla;^[35] she was surrendered at Sevastopol in November 1918.^[36]

[edit] Austro-Hungarian Navy

UB-1 and the still incomplete UB-15 were sold to the Austria-Hungary in February 1915; both were dismantled and shipped to Pola in May.^[37] After one cruise under the German flag, each boat was commissioned into the Austro-Hungarian Navy. The pair—renamed U-10 and U-11, respectively—were joined by U-15, U-16, and U-17 in October.^[3] Known as the U-10 or the Okarina (English: Ocarina) class as a part of the Austro-Hungarian Navy,^[38] the five boats operated primarily in the Adriatic in patrols off Italy and Albania.^[39] U-10 (ex UB-1) hit a mine in July 1918 and was beached, but had not been repaired by the end of the war. U-16 was sunk after she torpedoed an Italian destroyer in October 1916, but the remaining three (and the unrepaired U-10) were ceded to Italy at the end of the war.^[3]

[edit] Bulgarian Navy

After UB-8 was transferred to the Bulgarian Navy in May 1916, she was renamed Podvodnik No. 18 (in Cyrillic: Пoдвoдник No. 18). In Bulgarian service, the submarine was engaged primarily in coastal defense duties off Bulgaria's main Black Sea port of Varna. Podvodnik No. 18 survived the war but was ceded to France after the end of the war.^[4]

[edit] List of Type UB I submarines

There were a total of 20 Type UB I submarines built—17 for the German Imperial Navy and 3 for the Austro-Hungarian Navy.^[2][3] Two of the German submarines—UB-1 and UB-15—were sold to Austria-Hungary and commissioned into the Austro-Hungarian Navy as U-10 and U-11, respectively.^[2] Those two and a further three built by AG Weser comprised the virtually identical U-10 class for the Austro-Hungarian Navy.^[3] Another of the German submarines—UB-8—was sold to Bulgaria in May 1916,^[33] becoming Podvodnik No. 18, that nation's first submarine.^[40]

[edit] German Imperial Navy

• SM UB-1 (became Austro-Hungarian U-10, July 1915)
• SM UB-2
• SM UB-3
• SM UB-4
• SM UB-5
• SM UB-6
• SM UB-7
• SM UB-8 (became Bulgarian Podvodnik No. 18, May 1916)
• SM UB-9
• SM UB-10
• SM UB-11
• SM UB-12
• SM UB-13
• SM UB-14
• SM UB-15 (became Austro-Hungarian U-11, June 1915)
• SM UB-16
• SM UB-17

[edit] Austro-Hungarian Navy

In the Austro-Hungarian Navy the Type UB I boats were known as the U-10 class, which consisted of two former German UB I boats and three built specifically for Austria-Hungary.

• SM U-10 (Austria-Hungary) (the former German UB-1)
• SM U-11 (Austria-Hungary) (the former German UB-15)
• SM U-15 (Austria-Hungary)
• SM U-16 (Austria-Hungary)
• SM U-17 (Austria-Hungary)

In addition, five of the German UB Is assigned to the Pola Flotilla (German: Deutsche U-Halbflotille Pola), based at the Austro-Hungarian Navy's main naval base at Pola, were assigned Austro-Hungarian designations.^{[11][Note 4]}

• SM UB-3 (as U-9)
• SM UB-7 (as U-7)
• SM UB-8 (as U-8)
• SM UB-14 (as U-26)

These five boats remained under commission in the German Imperial Navy, retained German crews and commanders, and received orders from the German flotilla commander at Pola.

[edit] Bulgarian Navy

Germany and Bulgaria negotiated the purchase of two UB I boats for the Bulgarian Navy, UB-7 and UB-8 in 1916. Two crews of Bulgarian sailors were sent to Kiel for training. Before the purchase could be completed UB-7 was sunk, leaving only one boat for Bulgaria.^[4]

• Podvodnik No. 18 (the former German UB-8)

[edit] Notes

[edit] References

[edit] Bibliography