U27 class (1913)

Germany: SM U27, 28, 29, 30 (1913)

The U27 class submarine succeeded to the U23 double-hulled type, part of the “mittel-U” prewar super-class, or third U19 sub-class, all equipped with diesels. They originated indeed in Dantzig’s U19. The imperial shipyard (Kaiserliches Werft) at Kiel manufactured their own version of the MAN diesels under licence, and managed to gain an extra 100 hp compared to the U19 for extra speed for the next U23. A competition developed, in which Dantzig came back with a larger model than the U19 series, the U27. In between, MANs worked out better diesels with a surface speed being increased to 16.7 knots as well. Diving speed was improved, more oil was carried, so range was improved as well. The four U27 boats launched between July and November 1913 and completed before WW1 thus proved superior, and this led Germania Werft to answer with their own mass-built U31, launched in 1914. Their wartime career was mostly brillant, with U27 being the first submarine in history to sink another one (HMS E3).

SM U29 leaving Zeebruge for her last patrol under ace commander Otto Weddingen. The RN surface fleet had its collective revenge when no less than HMS Dreadnought spotted her periscopes and made for a ramming attack, which sank her will all hands. A payback for the loss of four cruisers in the hands of Weddingen. This was the only time in history, a submarine was rammed by a battleship.

Design of the U27 class:

Development

The U27 made by Danzig were basically a scaled up versions of their U19 class boats, with the extra space used to accommodate larger diesels and larger fuel tanks, whereas the hull was reworked with more powerful pumps and more generous ballasts in order to drive faster. These boats were a follow-up of the diesel-powered U19 class and rivalled the U23 class from the Imperial yard at Kiel. Kield managed to acquire the MAN diesel licence and created it’s own variant of these, extracting 100 hp more. These prewar “mittel U” in the official documentation were designated as medium range oceanic types, to which Danzig answered with an improved version in the U23 series.

However, it’s important to remember Germany, notably thanks to Tirpitz complete disregard of the U-Boat type, caused the Kaiserliches Marine to be late in the game, with the smallest fleet among belligerents, less than UK, France, Italy or Russia. Tirpitz later changed his mine and with early successes, some quite stunning, the budget for submarines was ramped up massively. Naval Yards were encouraged to increase production.
In the end, it must be stated that the technical similarities between the U19 and U27 (Danzig) U27 and U31 (Kiel) cause most authors to assimilated them all into a single “superclass”. If true, there will be a single article, which is not the case in many publications.

But nevertheless, being incrementally improved over a solid design perfected since 1911, and equipped with diesels, the U-Boats proved very successful, but Danzig will manage to outdo itself with the U-43 launched in 1914 (Project 25), a bit larger, a bit slower surfaced, but much faster in diving time. This rivalry between Germaniawerft in Kiel and Dantzig benefited much into the development of better U-Boats and with wartime scale
The U19 “superclass” when encompassing the U23, 27 and U31 boats (up to U41) when combined, with ready and trained crews when the war started produced the greatest tally of WWI submarines, rivalling the scores of the UB-II types or the UB-III which reached no less than 521 ships (1,123,211 GRT) and 7 warships, albeit they were smaller, cheaper, and far more numerous.

Hull and general design

The U27 class had the same dimensions as the U23 class, 64.7 meters long and 6.32 meters wide, with a draft of 3.45 meters, but displacement rose to 375 instead of 669 tons surfaced, 867 versus 864 tons submerged. The crew was the same and still amounted to 35 men, including four officers. Their 8.8 cm deck gun was supplemented by another one in 1916. However, some captains in 1914 still practicing the commerce raiding war prize rules (stopping the ships and then “scuttling” them by gunfire instead of a torpedo) complained about the 88 being a “weak calibre”, forcing them to stay surfaced way too long for the job.

Power plant of the U27

The U27 engines used for surface cruising were two MAN 6-cylinder 2-stroke diesels with a total output of 2000 hp instead of 1,800 hp (1,324 kW) which was achieved by Germania shipyard in Kiel for the U23. They were coupled with two SSW twin Modyn electric motors rated for a total of 883 kW (1,200 hp), so unlike the U19, Danzig produced U-Boats capable of a speed of 16.7 knots surfaced, albeit they were slower than the U23 underwater at 9.8 instead of 10.3 knots submerged. Operating radius was better, however, since they carried more oil, 104t versus 98t. The result was an increase to 7,900 nautical miles at 8 knots instead of 7,620 nm for the U23s at the same speed.

When submerged at a cruising speed of 5 knots, they reached the same 85 nautical miles (85 km), which is not surprising given they used identical electric motors. Maximum diving depth was 50 meters, like the U19 and U23, with a crushing depth double that, but the diving time was reduced to 80 seconds (or 1 minute 20 seconds) instead of 2 minutes and 13 seconds for the U23s. This certainly was the master ace of the class and set up a new record to follow for Kiel. The next U31 from Germaniawerft managed only to dive in a minute and 40 seconds, but they matched by Danzig, which U43 class boats were only capable of a minute and 45 seconds.

Armament

The U27 class did not change the recipe established even before U19: Four torpedo tubes, two each at the bow and stern like all their predecessors, and at 50 cm calibre (21 inches). Sources diverged over their carrying capacity, between six and ten torpedoes however, with the first being standard, including four already in tubes and two reloads forward only. There was a single 8.8 cm gun like their predecessors, forward, but this was soon raised to two. U30 was the exception, as she swapped her forward 8,8 cm for a 10,5 cm KL/45 (4.1 inches) in 1916. All also carried in 1916 a single 8 mm air-cooled machine gun, likely the Schwartzlöse for AA defence.

Torpedo Tubes

Germany started by equipping its torpedo boats and early U-Boats of the 1890s with the 35cm (14 in) C35/91 and C35/91GA, then 45cm (17.7 in) C45/91 Br, C45/91S, C/03 and C/03 D were reserved for surface ships, and the C/06 and C/06 D for U-Boats from U3 onwards. They stayed standard before the introduction of the 50 cm. The initial model was reserved for surface ships. This was the (19.7″) G/6 and G/6D which used either the Decahydronaphthalene (Decalin) or Kerosene Wet-Heater. The U23 was the first to introduce the new and famous G7 (entering service in 1913), repeated by the U27 class and follow-up U31 class. Still, there were important stocks of G/6, and it’s possible they were used for training or tests. The Kerosene powered G/6D was considered too “temperamental” for submarine use indeed. The G/6 was developed from 1908 and entered service in 1911. The Royal Navy was slower on this chapter, only introducing the 21″ (53.3 cm) Marks II, II* and II** for submarine use from 1914 onwards.
The four 500 mm (19.7 inches) torpedo tubes could be reloaded from above via the larger hatches going through the outer upper hull.

G/6 specs

Weight unknown, 236 in (6.000 m) lenght overall
Warhead 353 lbs. (160 kg) TNT/Hexanitrodiphenylamin (Hexanite) mixture
Range/Speed 2,410 yards (2,200 m) at 35 knots or 5,470 yards (5,000 m) at 27 knots
Power: Decahydronaphthalene (Decalin) Wet-Heater
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G7 Torpedo

The G7 was designed in 1910 and entered service in 1913. Originally designed for surface ships, but in 1917 it started to be used on U-boats.
Specs:
Weight: 3,009 lbs. (1,365 kg)
Overall Length: 276 in (7,020 m)
Explosive Charge: 430 lbs. (195 kg) Hexanite warhead
Range/Speed settings: 4,370 yards (4,000 m)/37 knots and 10,170 yards (9,300 m)/27 knots
Power: Decahydronaphthalene (Decalin) Wet-Heater

8.8 cm Schnelladekanone Länge 30 naval deck gun

For the U19 onwards, the classic 3,7 cm or 5cm deck guns were ditched out and as U19 was considered large and stable enough to have a larger gun installed and a single 88mm 27 calibre TK L/30 C/08 deck gun was installed forward. For this the deck was reinforced but no sponsons extensions appeared seemingly on photos.
In 1916, after captains reported this gun still weak, notably to scuttle a boarded ship or engage an armed trawler. They spent way too much time sinking their prey, which called for enemy reinforcements. Thus, all four boats had a second 8,8 cm deck gun installed aft, making two. U19 was the first U-Boat class with two guns, fore and aft. This was repeated for the U23 and U27 classes in wartime. U30 exchanged both guns for a single 10.5 cm/43 TK L/45 C/16 deck gun in 1918. The 8.8 cm became the standard go-to gun for all U-Boats built afterwards, until the U87 class (launched 1916), generally two for oceanic boats, one for minelayers and for later coastal subs. They accounted for many of their preys.

The 8.8 cm SK L/30 gun used the Krupp horizontal sliding block, or “wedge” and the submarine deck version was on either a retractable or fixed pivot mount. The Krupp mount retracted vertically through a hatch, and the Erhardt version folded down onto the ship’s deck. They avoided underwater drag and turbulences. It seems U19 class had the Ubts.L of the second type.
The 8.8 cm SK L/30 was a widely used naval gun on World War I pre-dreadnoughts, cruisers, coastal defence ships, avisos, submarines and torpedo boats in both casemates and turrets as well.
This calibre became so ubiquitous in the German Navy it was still a favourite for WW2 U-Boats as well starting with the Type VII. Read more

Specs 8.8 cm SK L/30 on Ubts.L mount

Weight: 644 kilograms (1,420 lb)
Overall length: 2.64 meters (8 ft 8 in).
Breech: Krupp horizontal sliding block
Shell: fixed 7 kg (15 lb) cal 88 mm (3.5 in)
Elevation: -10° to +30°
Rate of fire: 15 RPM
Muzzle velocity: 590 m/s (1,900 ft/s)
Maximum firing range: 7,3 km (8,000 yd) at 20° or 10,5 km (11,480 yards) at 30°

10.5 cm SK L/45 naval gun (1918, U30 only)

In late 1918, U30 only had her two 8,8cm deck guns replaced by a single 105mm deck gun with 300 rounds. The crew rose to 38 men less four officers, and now with a proper gunnery officer.
Built by Meddinghaus, this heavy deck gun was designed specially for deck use, low, with many sensible elements protected from corrosion.

Specs 10.5 cm SK L/45

1,450 kg (3,200 lb), 4.725 m (15 ft 6.0 in), 6.8 mm (0.27 in) wide.
Shell 10.5 cm (4.1 in) 25.5 kg (56 lb) fixed Brass Casing 17.4 kg (38 lb)
Breech: Horizontal sliding-block, MPL C/06: -10° to +30° mount
Rate of fire: 15 RPM
Muzzle velocity 710 m/s (2,300 ft/s)
Effective range 12,700 m (41,700 ft) at 30°

Author’s profile

⚙ U27 specifications
Displacement	675 t surfaced, 867 t submerged
Dimensions	64.7 x 6.32 x 3.5m (same as U23)
Propulsion	2 shafts MAN diesel engines 2000 hp, 2 × twin Modyn electric motors 1200 hp
Speed	16.7 knots surfaced, 9.8 knots submerged
Range	7,900 nmi at 8 kn surfaced, 85 nmi at 5 knots submerged
Armament	4× 50cm TTs (2 bow, 2 stern, 6-10 torpedoes), 8.8 cm SK L/40 gun
Max depth	50 m (160 ft)
Crew	4 officers + 31 men

Career of the U27 class

U27

U27 was ordered on 19 February 1912 at Kaiserliche Werft Danzig, as Yard N°17. She was launched on 14 July 1913 and commissioned on 8 May 1914 under Kapitänleutnant Bernd Wegener in command.
On 18 October 1914, she spotted HMS E3. The first submarine vs submarine action ever. E3 was coming from Harwich on 16 October, patrolling off Borkum, North Sea when on the 18th, she spotted some German destroyers ahead, but they were too fast for an attack. Cdr. Cholmley retreated into the bay, failing to spot U-27, surfaced, and patrolling between the Ems and Borkum. At 11:25 a spotter on the CT reported a “buoy” where no map showed any. Wegener suspecting a submarine, he dived, closed, until he could see by periscope “83” on its CT. He tracked her for two hours until able to approach in the best position, when its own spotters looked opposite to the sun and towards the Ems, where U-Boats and ships usually came from. When at 300 m (330 yd) her fired his two bow G6 torpedoes, causing 12 ec. later a detonation that ruptured the pressure hull. E3 went down with all 28 crewmen.

On 31 October, she spotted and sank the seaplane carrier HMS Hermes in the Straits of Dover, one of her best catch of the war. Then on 11 March 1915, she sank the armed merchant cruiser HMS Bayano off Carswell Point, Stranraer. On 18-19 May 1915 she sank Drumcree 11 miles NE of Trevose Head, Cornwall and Dumfries, 13 miles north of Trevose Head. On 18 August she was on a roll, sinking Ben Vrackie, Gladiator (both Britain), Magda and Sverresborg (Norway) and the Spanish Peña Castillo, after applying the war prize rules.
On 19 August she was roaming the Western Approaches when the White Star liner SS Arabic was sent her to the bottom (not by her, assumed to be a MAC). This was a human tragedy, perhaps one of the greatest before Lusitania. The news spread rapidly in the RN. The following day, many escorts were up to take revenge.

Later U27 spotted a freighter, which displayed the neutral American flag. This was in reality the Q-ship HMS Baralong. Forced to inspect her, Wegener surfaced and closed, after firing two rounds at the bow for her to stop. When close enough, asked for an inspection by megaphone and ready to send a launch, Baralong hauled down their flag, raised the White Ensign whereas panels hiding her guns went down. She fired immediately, leaving no chance to U27. The one-sided engagement saw U27 hit several times, sinking. Captain Herbert ordered to cease fire, but gunners were in bloodlust mode after hearing about the sinking of SS Arabic. She went down with all hands. Not because she had no survivors. Indeed, in addition to the crew not stopping fire upon order, Godfrey Herbert, acting under unofficial advice relayed by two officers of the Admiralty’s Secret Service branch (“Take no prisoners from U-boats”) ordered all 12 swimming survivors to be shot by small arms, which was duly obliged. The incident sparked outrage in Germany and fuelled the debate over unrestricted warfare. In fact, Germany instituted the Militäruntersuchungstelle für Verletzungen des Kriegsrechts, a bureau to investigate violations of laws of war and noted captain Herbert among these war crime captains.

U28

U28 was ordered on 19 February 1912 as Yard number 18, launched on 30 August 1913 and commissioned on 26 June 1914 under Freiherr Georg-Günther von Forstner in command.
Von Fortner was not judged too “timid” as indeed he soon met success by March 1915: On the 17th, he sank Leuuwarden (UK), on the 18th her captured both Zaanstrom and Batavier V (both Dutch), Medea (Dutch, sunk) on the 25th, all under war prize rules, then on the 27th, sank the British Aguila, South Point, Vosges, and a day later Falaba, City of Cambridge (damaged only), and on the 29th, Flaminian, Theseus (Damaged) and Crown of Castile.
On 30 July 1915, she sank the British steamer Iberian, reporting her remained underwater for about 25 seconds until an explosion sent debris flying up, describing among those a “gigantic aquatic animal” like a crocodile, something paranormal authors often cites. Was it simply a mis-identified zoo alligator ?
The following day, she sank Nugget and Turquoise, and on 1st August alone, Benvorlich, Clintonia, Koophandel (Belgian), Ranza and the following days, the AMC HMS Portia, the cargo ship Costello and Midland Queen. Note that is more torpedoes than she normally carried, showing she sank some by gunfire.

She was overhauled next, and was back at sea in March 1916. On 15 June 1916 Otto Rohrbeck took command, but met little success. He was dismissed and replaced on 5 August by Freiherr von Loe-Degenhart. He too, was more successful. Furthermore, she bagged the Norne, Rio Tiete, Trewyn, Saint Hubert, Vigo (Spanish) and on 1 April 1916, Bengairn. From 15 January 1917, Georg Schmidt took command, meeting more success than von Forstner: In May 1917, 29th he sank the Norwegian Fridtjof Nansen, Karna and Kodan. On 3-5 June, Merioneth, Algol (Russia), Alaska, Duen, Sydkap (Norway), Manchester Engineer, Sverre II, Marie Elsie, Perla and in August Hidalgo, Whitecourt, Marselieza (Russia) and on 1 September Dront (Russia) and a day later Olive Branch (UK).

This was U28’s last kill. That patrol started on 19 August from Emden in the Arctic but on 2 September, at 11:55 am, when encoutering the steamer Olive Branch underway to Arkhangelsk, 85 nautical miles off North Cape she scored a torpedo hit, closed in to finish her off by gunfire after spend all her torpedoes. Unfortunately, she closed further to make the best of her two 8.8 cm guns when one shell hit her apparently massive ammunition stocks. The detonation was gigantic. The ship went up in an immense column of flames, while the blast wave rocked U-28 and ruptured the pressure hull. Debris fell in her, damaging the CT. Damage was so bad, she sank with all 39 crewmen. Some were still swimming, but were abandoned by Olive Branch’s survivors in their lifeboats. Other sources described a completely different version, in which the ammunition detonating sent heavy deck cargo flying and falling on U28, breaking her pressure hull. Either way, this was a rare occurrence, and Olive Branch (the ironically well named) was avenged, involuntarily applying the talion law.

U29

U29 was ordered on 19 February 1912, as Yard number 19, launched on 11 October 1913 and commissioned on 1st August 1914. Her first patrol, under Kptlt. Wilhelm Plange, brought no results, until famous submariner Otto Weddigen took command. He soon bagged 4 ships, total of 12,934 tons and damaged two for 4,317 tons: On 11 March 1915 Adenwen (3,798t, Damaged), and Auguste Conseil (France, Sunk), then the following day, Andalusian and Headlands. On the 12h, he bagged Indian City. Two days later only managed to damage the small steamer Atalanta. Weddingen had been famous for his sinking of three British Armoured Cruisers (Cressy, Hogue and Aboukir) in a single action on U9, on 22 September 1914. He also bagged the cruiser HMS Hawke off Aberdeen on 15 October plus three cargo ships, being awarded the rare Pour le Mérite (Blue Max). So for the RN, he was on top of the “hit list”. He was injured, however, and after some time, took command of U29. His last cruise started on 10 March 1915 from Zeebruge. After the successes described above, on 18 March, he met the Grand fleet in the Pentland Firth, between the mainland and Orkney Islands. Lookouts on HMS Neptune saw her first (she dived after a missed shot). HMS Dreadnought saw the latter periscope and headed for the almost immobile target. The battleship sped up the maximum the boilers could do, and managed, thanks to her draught to score a direct hit on her hull, which broke. U29 and her famous captain sank. She became the only submarine known to have been purposefully sunk by a battleship in history, and RN’s honour was restored.

U30

U30 was the only one to survive the war. She was ordered on 19 February 1912 as Yard number 20, launched on 15 November 1913 and commissioned on 26 August 1914, so her first patrol was a wartime one, after some training. Her tally was the second largest after U28, mostly in 1915 and 1917. She entered service under Erich von Rosenberg-Gruszczynski (Royal House Order of Hohenzollern) from 25 September, attached to the IV Flotilla. He first patrol in late April until 3 May, brought down Cambank, Downshire, Mobile, Cherbury, Fulgent, Svorono, Edale, Europe, Gulflight and Minterne. SS Gulflight was a peculiar case, as she was American.

On 28 April U-30 intercepted the 1,905 GRT collier Mobile, sank by gunfire according to prize laws, with the craw safely out. On 29 April the same with the 3,220 GRT Cherbury and on 30 April she ordered the steamer Fulgent to halt, fired forward of her bow, and when Fulgent refused to budge, she fired a shot into the bridge, killing the captain and quartermaster. She stopped, the crew escaped. A party was sent to scuttle her with explosive charges. In the afternoon, the 3,102 GRT Svorno was stopped and sunk and on 1 May the grain carrier Edale and French ship Europe, as well as a Dutch ship stopped and inspected, then the steam drifter Clara Alice when she was reported and hunted down by the patrol ships HMS Iago and Filey. In between she spotted the US-flagged Gulflight, under escort, a breach of neutrality under international law. So U30 sent one torpedo at Gulflight before noticing that her flag. She broke off the attack and Gulflight survived, towed to Crow Bay and later repaired. But with the loss of Lusitania she was added to a list of complaints to Germany as a breach of “cruiser rules”.

U30 had a refit and from May 1916, Kptlt. Franz Grünert (Royal House Order of Hohenzollern) took command. on 26 October she sank Lysland (Norway) and on 1 November Brierley Hill. After another patrol which was uneventful, she made her largest tally of the war: On 11 April 1917 alone she sank the Danish Saxo, Nancy, Norwegian Star, Sylfiden and a day later, Kolaastind, then on the 13h, Bokn, Frixos (Finland), Gama, Glenlora, the british Zara and the next day Fjeldli, then on the 15th the Norwegian Paris and on the 16th, Middlesex (7,265 GRT, her biggest kill of the war).
Her next patrol brought poor resuls: On 23 May she bagged the Danish Freden. Fast-forward for her last patrol, on 16 July she sank the Russian Cyrus and on the 28th, the French Atlas.
After a refit, she was considered obsolete and sent from 19 Nov 1917 to the training Flotilla. On 22 Nov. 1918 she was Surrendered to Britain, and broken up at Blyth in 1919-20.