Mackensen class Battlecruiser (1917)

The Mackensen were the penultimate German battlecruiser design, following the Derfflinger class and in particular, the third ship in class, SMS Hindenburg. They were far more than paper projects, as SMS Mackensen had been launched on 21 April 1917 and was 15 months from completion when the war ended. News of their construction from early 1915, and knowledge they would be armed with 35 cm main guns, be faster and better protected than the 1913 Derfflinger, led the British admiralty to order the Admiral class in response, also cancelled in late 1918 with only the famous HMS Hood completed. There were seven ships of this class originally planned, but later only four were approved as they were, with the last three redesigned as the 38 cm armed Ersatz Yorck class. Given both their speed and levels of protection, they prefigurated interwar fast battleships and many of their design aspects found their way into modern Kriegsmarine capital ships designs.

Development

The Mackensen class originated from the 4th and final Naval Law of 1912, largest expansion of the Kaiserliches Marine (German navy) until 1914 and even affecting ships completed during the war, when the Imperial Naval Office (Reichsmarineamt) decided to go for a formula of a battleship and a battlecruiser yearly until 1917. Design work for the class to replaced the Derrfflinger in construction started back in 1912 already, and construction was scheduled to start as per the 1914 budget year. The main hot topic for discussion was their main battery. Many approved the move from 28 cm to 30.5 cm guns for the Derfflinger class (12 in) and it was even argued that the last two in class, SMS Lützow and Hindenburg could have been rearmed wit even better 35 cm (13.8 in) guns, the latest adopted on battleships.

The 35 cm guns were heavier and eventually engineers recoignized that the size of the new barbettes would have imposed major redesigns and eventually enlarge the ships altogether. But at the time, the Imperial dry docks were only deep for warships having a draft of 9 m (30 ft). It was also recoignized that if the same hull was kept the increased displacement would reducted top speed. More displacement inevitably entailed a longer and wider hull to keep the draft compatible with the existing docks. The extra size would allo the installation of extra boilers, potentially larger turbines, and preserve speed, the very nature of a battlecruiser. As for making the hull wider and longer, more limitations appeared, the restrictions, especially for the beam, of the locks of the Wilhelmshaven canal. Großadmiral Alfred von Tirpitz thus ordered not to go beyond 30,000 metric tons (29,526 long tons). Engineers now had to fit in this limitation eight 35 cm guns and larger if possible.

The initial design was approved on 30 September 1912. However Vizeadmiral Günther von Krosigk and Konteradmiral Reinhard Scheer at the head of the General Navy Department, and Vizeadmiral Gerhard Gerdes (Weapons Department) submitted revisions, notably trying to implement triple or even quadruple gun turrets as a way to spare barbettes and reduce weight. Another option was to go from four twin 35cm to three twin 38 cm (15 in), one forward, two aft to reduce the center of gravity. The Emperor, Wilhelm II, accepted the final design on 2 May 1913. Admiral Friedrich von Ingenohl, at the head of the High Seas Fleet however, preferred to keep the 30.5 cm gun of the Derfflinger-class. In the end, the design stuck to the initially planned eight 35 cm (13.8 inch) guns in four twin turrets, same arrangement as the Derfflingers.

Other questions were subsidiary. The same protection as the Derfflingers was earmarked, notably with a 30 cm (12 in) Krupp Cemented armour belt. The machinery department however left questions in balance over the type of combustible to be used: Oil-fired boilers only, of a mix with coal. Indeed at the time, Germany was still not at war, and its burgeoning colonial Empire was a potential source for oil. In the end, another compromise was chosen by the design staff which adopted 2/3 coal-fired boilers, 1/3 oil-fired boilers. The Coal-fired boilers had the indirect advantage of having soal, stored in normally voild sides compartiments of the ship counting as additional protection. This finalized design was approved on 23 May 1914, still three months before the war.

Design of the class

Hull and general design

From warship internaitonal 1974
The general outlook of the Mackensen class would be similar to the Derfflingers and in particular, the last ship in class, Hindenburg, which diverged from her sisters on many points. The hull chosen was to be also flush deck, without forecastle, to spare weight, but on a longer base, 223 m (731 ft 8 in) long for 30.4 m (99 ft 9 in) in beam and a draft contained to 9.3 m (30 ft 6 in) forward and 8.4 m (27 ft 7 in) aft. To compare, the Derfflinger class measured 210.40 meters (690 ft 3 in) overall for a beam of 29 meters (95 ft 2 in) and draft of 9.20 meters (30 ft 2 in) mean.
The Mackensen were designed for 31,000 t (30,510 long tons) on standard load, and up to 35,300 t (34,742 long tons) fully laden to compare to 26,600 tonnes (26,200 long tons) normal and a 31,200 tonnes (30,700 long tons) full load on the Derfflingers. For another comparison, the British Repulse class were 27,200 long tons normal load and 32,220 long tons deep load as completed, so the Mackensens were much beefier.
The Mackensens had their hull architecture using classic longitudinal steel frames, with reiveted hull plates, same as the previous class and intended to save weight instead of the previous method of longitudinal and transverse frames. For ASW protection they had 18 watertight compartments plus a double bottom for 92% of the hull lenght, greater than the Derfflinger-class (65%).

The Macksensen hull was not as sloped as for the Derfflinger, and taller. There were two portholes lines at the forward and aft end, outside the belt, one anchor either side, a straight stem, and a straight sloped chin acting as icebreaking bow for winter, icy operations. There were two counter keels. The German design stuck at that stage to lower casemate guns for secondary armament, and they were placed alongside the structure created by the forward recess break of the prow. This recess allowed four guns to fire directly ahead, two aft, with a narrow deck space all the way to the stern. For the same reasons as the previous design, the four turrets were not spaced like traditional superfiring pairs. The raising of one level of the deck aft was necessary to avoid the aft casemates to be awash when steaming at high speed, even in calm seas. In addition to be straight and end with a icebreaking chin, there was a bulbous bow to reduce drag, an innovation of this design learned from pool model tests. The US went for the same solution for their own Constellation class battlecruiser.

“A” and “B” were located close together forward, but “X” and “Y” were separated by a wide space used for an air intake structure for the machinery. Other ventilation “louvres” instead of the classic dorade boxes, were located at the base of the upper structure. The latter was short, about 1/3 of the full lenght, acting as an island on which were located successively the base for the conning tower and its forward balcony bridge, the robust tripod mast inspired by Hindenburg, sporting two signal lamps, two searchlights, a first spotting top and at the very end a two-level fire control tower crowned by a main rangefinder.
If the ships -in a parallel universe- had been completed as intended, and kept in the interwar, it’s very likely the tripod would have been “populated” by extra platforms like Japanese and British designs over time.

Past the bridge and mast was the forefunnel, quite large, for 2/3 of the exhausts, with flat sides. Behind was the “inter-island” space on which were stacked six main boats, whalers, yawls and two vedettes (motor cutters). In archive these were two picket boats (motor boats), one barge, two launches, two cutters, and three yawls. The smaller would be likely under side davits. Then came the aft funnel, smaller, straight and with flat sides as well, axhausting the remainder 1/3 of the powerplant. Anchored on its aft side were series of utility platforms sandwiched with the aft pole mast. Behind it was located the aft conning tower, smaller, simpler and crowned by the secondary armament’s fire control and rangefinder. There were extra searchlights on seither side of the fore funnel, and four on the aft funnel. The boats were managed by two cranes located abaft the aft funnel. The crew was to comprise 46 officers and 1,140 enlisted sailors, but as squadron flagship an extra 14 officers and 62 sailors needed accomodations.

Powerplant

The Macksensen class essentially reproduced the Derfflinger’s machinery, with more power: Having steam turbines causes no debate, so they had four strut-suspended shafts with classic 3-bladed 4.2 m (13 ft 9 in) disameter bronze fixed pitch propellers, driven each by a set of marine-type turbines. But they diverged: Mackensen, Graf Spee, and Ersatz Freya would have Marine steam turbines plus 32 Marine boilers when the last ship in class, Ersatz A was to have new Marine geared steam turbines but the same 32 Marine boilers. Ersatz A (later Fürst Bismarck) indeed was to have a Föttinger fluid transmission, and all the others the same two sets of direct-coupled turbines, with geared transmissions.
The “boiler park” comprised 24 coal-fired marine-type single ended boilers plus eight oil-fired marine-type boilers. All this provided some 90,000 metric horsepower (89,000 shp) at 295 revolutions per minute. Top speed was 28 knots (52 km/h; 32 mph), and steering agility was provided by two rudders mounted side by side, replacing the tandem rudders of the Derfflinger-class. This too, was an innovation obtained by pool model studies.
The last ship’s Föttinger gears were found to significantly improved performance at cruising speed making for a range increase of about 20%, when normal storage was 800 t (790 long tons) of coal and 250 t (250 long tons) of oil. They were placed in purpose-built storage spaces, hull areas placed between the torpedo bulkhead and outer wall able to receive additional fuel for a maximum capacity of 4,000 t (3,900 long tons) of coal, 2,000 t (2,000 long tons) of oil in wartime for a range of c8,000 nautical miles (15,000 km; 9,200 mi) as calculated, for a cruising speed of 14 knots (26 km/h; 16 mph). When the engines were cold, there was enough Electrical power for armament and emergency systems, provided by eight diesel generators which together were rated for a total of 2,320 kilowatts at 220 volts.
To cmpare, Hindenburg had 4 Marine steam turbines but only 18 Marine doubled boilers for 72,000 hp and 27 knots, 6,100 nm range at 14 knots. So going from 72K to 90K hp only brought an extra knot in speed.

Protection

The base rule was to use Krupp Cemented Armour for all vitals. Exact Specific figures for the arrangement are unknown. However acclaimed author Erich Gröner on the scheme stated the outfit was similar to that of the Derfflinger class and thicknesses were pretty close as well:
Armor belt 300 mm (11.8 in) for the central citadel (ammunition magazines and machinery spaces)
Outer belt 120 mm (4.7 in) forward and 100 mm (3.9 in) aft, tapered down to 30 mm (1.2 in) at the bow, nothing at the stern
Torpedo Bulkhead 45 mm (1.8 in) all length meters behind the main belt.
Main armored deck 30 mm outer space and 80 mm (3.1 in) on top of the citadel
Forward conning tower: 300 mm thick walls, roof 130 mm (5.1 in).
Rear conning tower: 200 mm (7.9 in), roof 50 mm (2 in).
Main battery gun turrets: 270 mm (10.6 in) fwd and side, roof 110 mm (4.3 in).
15 cm guns casemates: 150 mm (6 inches); Gun shields 70 mm (2.8 in) shields.
8,8cm gun shields: Likely 20mm (1 inch)
Fire control Tower: Probably 20 mm vs. shrapnel

Armament

Main: 4×2 35cm SK/L45

The Mackensen class had in all eight new 35 cm SK L/45 guns in four twin gun turrets, in superfiring pairs fore and aft and C/1914 mounting elevate to 20 degrees, depressing to −5 degrees. A supply for each gun of 90 AP (armor-piercing) shells, or 720 total was provided.

Specs:

Shell: 600 kg (1,323 lb) AP. Fore propellant charge in a silk bag, main charge in brass case.
Rate of fire: c2.5 shots per minute.
Muzzle velocity: 820 meters per second (2,700 ft/s).
Max Range: 23,300 m (25,500 yd).

Secondary: 15 cm (5.9 in) SK L/45

Fourteen 15 cm (5.9 in) SK L/45 quick-firing guns in armored casemates, central superstructure. 160 rounds each.

Specs:

Shells: 45.3 kg (99.8 lb) with 13.7 kg (31.2 lb) RPC/12 propellant charge in brass cartridge.
Muzzle velocity: 835 meters per second (2,740 ft/s).
Rate of fire: 7 rounds per minute.
Max range: 13,500 m (44,300 ft), later extended to 16,800 m (55,100 ft).
Barrel life: 1,400 shots.

8.8 cm L/45 FLAK

First designed by Krupp in 1905.
There were eight 8.8 cm (3.45 in) L/45 Flak guns in single pedestal mounts around the rear superfiring main battery turret and forward conning tower, all in shielded C/13 mountings

Specs:

Barrel: 45 calibres (approx. 4 metres / 13.1 feet)
Depression: −10 degrees, elevation +70 degrees.
Total Weight: 2,500 kg (5,512 lbs)
Rate of Fire: 15 rpm
Muzzle Velocity: 650 to 890 m/s depending on charge
Shell: 9 kg (19.8 lb)
Effective ceiling: 9,150 m (30,020 ft)/70°

Five 60cm TTs

As standard there were five submerged torpedo tubes, all 60 cm (24 in) tubes, one in the bow, two paired either side, but none in the stern.
Type: H8. Lenght 9 m (30 ft) for a 210 kg (463 lb) Hexanite warhead. Range of 8,000 m (8,700 yd) at 35 knots (65 km/h; 40 mph) for fast setting and 28 knots (52 km/h; 32 mph) for 15,000 m (16,000 yd) for the max range setup.

⚙ Mackensen specifications
Displacement	31,000 t (30,510 long tons) standard, 35,300 t (34,700 long tons) full load
Dimensions	223 x 30.4 x 9.3m (731 ft 8 in x 99 ft 9 in x 30 ft 6 in)
Propulsion	4 shafts geared steam turbines, 32 boilers, 90,000 hp (89,000 shp)
Speed	28 knots (52 km/h; 32 mph)
Range	8,000 nmi (15,000 km; 9,200 mi) at 14 knots
Armament	8× 35 cm SK L/45 guns, 14 × 15 cm SK L/45, 8 × 8.8 cm SK L/45 Flak, 5 × 60 cm TTs
Protection	Belt 100–300 mm, Turrets 270 mm, deck 30 to 80 mm, CT 300 mm
Crew	46 officers + 1,140 enlisted men

Construction and Fate of the Mackensen class

The lead vessel SMS Mackensen was laid down under the 1914-15 programme, Ersatz Freya under the War estimates, the others were ordered in April 1915. It was originally hoped to complete them from the summer of 1917 to the autumn of 1918. Names later assigned were Prinz Eitel Friedrich for Ersatz Freya Ersatz, Ersatz Friedrich Carl for “A” and eventually Fürst Bismarck, and armoured cruiser lost earlier. Plus there was the need for at least a capital ship named “Bismark” in the Imperial Navy. The four ships eventually built to the Mackensen design proceeded by a first order on 14 August 1914, shortly after the war started, with Mackensen being the last and only to be funded through the 1914 budget. The next would be under the war budget.

SMS Mackensen was initially known as Ersatz Victoria Louise as the class was to replace either obsolete or sunken cruiser, in that case, this was the old protected cruiser Victoria Louise. The final name honored Generalfeldmarschall August von Mackensen, famous for his Pelzmütze ornated by a Prussian totenkopf from the elite life Hussards. The “last hussard” was also a hero of the eastern front, with the Group he commanded. She was laid down on 30 January 1915 at Blohm & Voss in Hamburg, construction number 240. She was launched on 21 April 1917. Were present at the ceremony Generaloberst Josias von Heeringen for a speech. She was christened by Mackensen’s wife. Construction stopped after 15 months before completion, despite British room 40 intel reporting she was completed, so she was listed for internment for Scapa Flow instead of Baden, until her true state was realized. SMS Mackensen was stricken under the Treaty of Versailles on 17 November 1919, sold for scrap and broken up in 1922, at Kiel-Nordmole.

SMS Graf Spee honored the memory of Vice Admiral Maximilian von Spee, commander of the East Asia Squadron, killed at the Battle of the Falkland Islands in 1914. The ship was laid down on 30 November 1915 in Schichau yards, Danzig (Gdańsk, Poland) initially as “Ersatz Blücher” to replace the recently sunk armored cruiser Blücher at the Battle of Dogger Bank in January 1915. She was launched on 15 September 1917, so much later than her sister. At the launching ceremony was present for a speech Großadmiral Prince Heinrich and the countess and widow Margarete christened the ship. Construction stopped 12 months from completion. So she was the most advanced and cloe to full completion of all ships in class. She too was struck on 17 November 1919 and sold for BU on 28 October 1921, broken up in Kiel-Nordmole.

Hamburg port. Unfinished hulks: Mackensen-class battlecruiser “Prinz Eitel Friedrich” (larger of the two) and Bayern-class battleship “Württemberg” (smaller of the two).
Prinz Eitel Friedrich was initially Ersatz Freya, replacement for SMS Freya and named for the prince Eitel Friedrich. She was laid down in 1915 at Blohm & Voss under construction number 241, never officially launched and suspended, 21 months away from completion. She was launched as she was, to clear the slipway on 13 March 1920, broken up at Hamburg in 1921. The “ceremony” was attended mostly by the yard’s staff and dockyard workers, which renamed the ship “Noske” after Reichswehr Minister Gustav Noske.

Ordered as “A” or Ersatz Friedrich Carl, and later to be officially named Fürst Bismarck for the famous chancellor she was eventually officially a replacement ment for the armoured cruiser SMS Friedrich Carl. She was laid down in 1915 at Wilhelmshaven Imperial Shipyard, under construction number 25 and c26 months from completion when suspended. Never launched (she was at risk to sink when in water), she was instead, broken up on slip in 1922 to clear it.

Follow-Up: The Ersatz Yorck

The Ersatz Yorck class was a planned group of three heavy battlecruisers ordered for the Imperial German Navy in 1916. Representing the pinnacle of World War I German battlecruiser design, they were designed as a direct response to British 15-inch gunned battlecruisers like HMS Repulse as well as the results of the battle of Jutland, later which delayed construction due to design revisions. However, due to shifting wartime resources and a strategic pivot toward U-boat production, none of the ships were ever completed. The vessels were to be named provisionally Ersatz Yorck, Ersatz Gneisenau, and Ersatz Scharnhorst and intended to replace older armored cruisers lost early in the war.

From Mackensen to Ersatz Yorck, the latter were initially ordered as the final three hulls of the preceding Mackensen-class battlecruiser. However, when German intelligence discovered that Great Britain was building ships with 15-inch (38.1 cm) armaments, the design was drastically reworked into the GK6 blueprint. To accommodate significantly heavier firepower while using materials and machinery already ordered, German engineers lengthened the hull and consolidated the boiler exhaust into a single, massive central funnel—marking the first time a German capital ship featured this distinct silhouette.
These Battlecruiser would have displaced 33,500 tonnes (Normal) and 38,000 tonnes (Full Load) for an overall length 227.8 metres (747 ft 5 in)
Speed 27.3 knots (50.6 km/h).
Main Armament: 8 × 38 cm (15 in) SK L/45 guns in four twin turrets
Secondary Armament: 12 × 15 cm (5.9 in) SK L/45 guns
Anti-Aircraft: 8 × 8.8 cm Flak L/45 guns
Armor Belt: 100 to 300 mm (3.9 to 11.8 inches)
The Lead Ship (Ersatz Yorck) was laid down in July 1916 at the AG Vulcan shipyard in Hamburg. Work progressed only on the midship section of the hull before construction was halted. It was abandoned in early 1918 and eventually broken up on the slipway. Ersatz Gneisenau and Ersatz Scharnhorst were never officially laid down. Materials gathered for them were cannibalised; notably, diesel generators originally earmarked for Ersatz Gneisenau were rerouted and installed into Germany’s large Type U-151 fleet submarines. Their structural layout and single-funnel engineering concepts pioneered in the Ersatz Yorck blueprint directly served as the foundational starting point for the Scharnhorst-class battleships.

Read More/Src

Books

Campbell, N. J. M. & Sieche, Erwin (1986). “Germany”. Gardiner, Robert & Gray, Randal. Conway’s All the World’s Fighting Ships 1906–1921.
Dodson, Aidan (2016). The Kaiser’s Battlefleet: German Capital Ships 1871–1918. Barnsley: Seaforth Publishing.
Dodson, Aidan (2017). “After the Kaiser: The Imperial German Navy’s Light Cruisers after 1918”. Warship 2017.
Friedman, Norman (2011). Naval Weapons of World War One: Guns, Torpedoes, Mines and ASW Weapons of All Nations. Illustrated Directory.
Grießmer, Axel (1999). Die Linienschiffe der Kaiserlichen Marine: 1906–1918; Konstruktionen zwischen Rüstungskonkurrenz und Flottengesetz. Bonn: Bernard & Graefe Verlag.
Gröner, Erich (1990). German Warships: 1815–1945. Vol. I: Major Surface Vessels. NIP
Herwig, Holger (1998) [1980]. “Luxury” Fleet: The Imperial German Navy 1888–1918. Amherst: Humanity Books.
Hildebrand, Hans H.; Röhr, Albert & Steinmetz, Hans-Otto (1993). Die Deutschen Kriegsschiffe: Biographien. Vol. 3. Ratingen: Mundus Verlag.
Staff, Gary (2014). German Battlecruisers of World War One: Their Design, Construction and Operations. Barnsley: Seaforth Publishing.
Weir, Gary (1992). Building the Kaiser’s Navy. Annapolis: Naval Institute Press.
Campbell, N. J. M. (1978). Battle Cruisers. Warship Special. Vol. 1. Greenwich: Conway Maritime Press.
Dodson, Aidan; Cant, Serena (2020). Spoils of War: The Fate of Enemy Fleets after the Two World Wars. Barnsley: Seaforth Publishing.
Koop, Gerhard; Schmolke, Klaus-Peter (1998). Die Grossen Kreuzer Von der Tann bis Hindenburg. Bonn: Bernard & Graefe.

Links

german-navy.de/
sms-navy.com
navypedia.org
stefsap.wordpress.com
en.wikipedia.org
de.wikipedia.org

Model Kits

scalemates.com ModellbauRay, NNT Modell+Buch 1:700
on ebay.com

3D

https://www.fab.com/listings/5628f4c5-41a8-4558-859d-e10315f30274?lang=deske
https://embed-3dwarehouse-classic.sketchup.com/model/56c19c2b-b4c4-4b9b-94d2-c9592d7e5ef7/SMS-Mackensen