Daegok-class battlecruiser

The Daegok-class was a pair of battlecruisers built for the Menghean Navy in the 1910s. Both ships were built in Anglia and Lechernt, which which confiscated them during construction to serve in the Royal Navy during the War of the Siennese Succession. They were delivered to Menghe in 1920, and were among the eight capital ships retained by Menghe under the Selkiö Naval Treaty.

Both ships underwent extensive mid-life reconstruction in the late 1920s, receiving improved armor, torpedo bulges, a revised secondary battery layout, and a new powerplant. These changes raised their top speed from 27 to 29 knots.

Development, Construction, and Early Service

The Daegok-class battlecruisers were ordered as a response to the Kongō-class battlecruisers rumored to be under construction in Dayashina. With a high design speed and a 14-inch main battery, the Kongōs were clearly superior to Menghe's newly-ordered Baekjin-class battlecruisers, which were supposed to represent the mainstay of Menghe's commerce-raiding operations in the event of a war with Dayashina. A battlecruiser ordered in response would have to match the Kongō class in speed, while carrying armor thick enough to withstand 14" shells at probable combat ranges. The Navy began work on a design for these requirements, under the project name Plan 24. The need to sustain high speeds with thicker armor resulted in additional draught and repeated revisions to the design, meaning that it could not be constructed in Menghean yards. Menghe solicited foreign builders, eventually negotiating a contract with Anglia and Lechernt, which also completed detailed design work.

Two hulls were ordered in the first batch, with an option for two more. The first, Daegok, was laid down on 4 March 1914; her sister Ranju was laid down in April of the same year. Following the outbreak of the WSS, Anglia and Lechernt forced the sale of both ships to the Royal Navy while they were still under construction, completing them to a slightly modified design and bringing them into service in late 1916. For the next three and a half years, they served in the Anglian Royal Navy, at one point deploying across the Meridian Ocean to support Anglian operations against the Ostish colony of Kussein. At the end of 1919, as the WSS came to a close, Anglia and Lechernt agreed to return the two battlecruisers to Menghe. After a difficult voyage across the Meridian Ocean, and some modifications to carry Menghean weaponry, both ships were formally commissioned into Menghean service on 19 February 1920.

Description (as built)

As built, the Daegok-class battlecruisers had an overall length of 223.8 meters, a beam of 30.45 meters, and a draft of 10 meters at full load. At full load they displaced 34,807 tonnes; under the Selkiö Naval Treaty, their standard displacement was calculated as 29,102 tonnes.

Propulsion

The initial propulsion system for the Daegok-class battlecruisers consisted of directly-coupled turbines driving four propeller shafts. These were fed by steam from no fewer than 48 boilers divided between 12 watertight compartments. Total power was rated at 84,000 shp, for a top speed of 26.9 knots under normal loading conditions. This ended up leaving them slightly slower than the Kongō-class battlecruisers they were meant to pursue.

The boilers normally burned coal, but could be sprayed with oil for accelerated output. Oil made up 20% of the fuel bunker, which enabled a maximum range of just over 8,000 nautical miles at 14 knots.

Exhaust from the boilers was trunked initially into three funnels. Operational experience soon revealed that smoke made the aft spotting station almost entirely unusable, and interfered with the spotting positions on the forward superstructure as well. A thumbnail-like deflector was added to the forward funnel of Daegok in 1923 to reduce smoke on the forward superstructure, but this was found to be inadequate in practice.

Armament

The ships' main battery consisted of eight 14" (356mm) 50-caliber guns distributed across four two-gun turrets. These were Gothian-designed weapons, and were supposed to offer superior muzzle velocity and range compared to the Dayashinese 14"/45. The increased muzzle velocity, however, came at the cost of increased wear and shortened barrel life, resulting in deteriorating performance over time. The initial turret mountings enabled a maximum elevation of 20 degrees, for a range or 22,310 meters, meaning that these ships were actually outranged by the Kongō class. Rate of fire was cited as 2 rounds per minute, with reloading possible at any elevation from -5 to +20 degrees. The aft turrets were designed to have excellent firing arcs of +/-160 (Y) or +/-153 (X) degrees, though these narrow arcs were found to damage the aft superstructure and in particular the stored boats. Ammunition storage was 90 rounds per gun.

The secondary battery consisted of sixteen 6"/45 BL Mark VII guns in casemates distributed around the hull. These had an elevation of 20 degrees for a maximum range of 14,450m when using heavy charges. Rate of fire was 12rpm in firing trials and 4rpm in battle practice, with a total of 1,920 stored rounds. In keeping with contemporary construction practice for their own ships, the Royal Navy added separate directors and fire-control computers for these guns during final construction, something the Menghean Navy would carry forward to future designs of their own.

Based on lessons from late-19th and early-20th century conflicts, where small-caliber and high-explosive gunfire was found to play a large role in stripping battleships of their lighter self-defense guns, all secondary guns were installed in the upper casemate of the hull, protected by six inches of vertical armor and one inch of horizontal armor. The casemate cylinders were also six inches thick. Because of their low placement in the hull, and because of the hull's low freeboard, these casemates were notoriously uncomfortable at high speeds and in heavy seas. Fold-down cover screens were installed around the edges of the casemates to better shield the interior when out of battle, but these had to be lowered in battle to allow the guns to traverse, and even out of battle crews reported that the screens were not totally effective at keeping out sea spray.

Anti-air armament initially consisted of four 12pdr/20cwt (3"/45) QF HA Mark I guns installed in single mounts on the main deck. These were also added during construction after the Royal Navy confiscated the two hulls. After the Menghean Navy received the ships, they replaced these with 75mm Type 16 guns in Type 16 high-angle mounts. A minor refit in 1922 raised these mountings to an enclosed "tub" one deck higher in an effort to reduce the effect of sea spray, replacing them with the Type 22 version of the mount in the process. Various Maxim guns were added around the deck and superstructure for close-range AA defense, with the number and location of these mounts varying from ship to ship and year to year.

Like many contemporary capital ships, the Daegoks were completed with submerged torpedo tubes. The first torpedo room, located forward of the "A" turret, had two forward-facing tubes and six reloads. The second torpedo room, located between the "B" turret and the boiler spaces, had two side-facing tubes and four reloads.

Protection

Vertical armor protection consisted of a 12" main belt and a 6" upper belt, as well as 4" fore and aft belts. As final design and construction took place in Anglia and Lechernt, all armor thicknesses were incremented in inches. The main belt measured 3.81 meters high, or just 60 centimeters below the waterline at light load conditions, and the upper belt fully enclosed the casemate deck. The main belt of the Daegok class compared favorably to the main belt of the Kongōs, offering good protection against 14" shells. The main battery turrets were protected by 12" faces and barbettes, 10" sides, and 6" roofs.

Horizontal armor over the citadel was divided between two decks: a 1" upper deck connecting the upper belt at its top, and a 2" main armor deck with "turtleback" edges connecting to the base of the main belt. Outside the citadel, a 1" armor deck covered the steering gear aft and the torpedo room forward. This was reasonable for the time of construction, but increases in combat range over the course of the WSS made this armor scheme vulnerable to plunging fire, and it was substantially strengthened in reconstruction.

The Daegok-class ships were built without substantial torpedo protection. Bulkheads on either side of the magazine and machinery spaces provided a measure of protection, but these were made from soft structural steel rather than armor steel, and grates at their bases allowed the dumping of coal (and, if punctured, water) into the citadel. The width and length of the straight-walled machinery spaces, compared to the curvature of the hull, also meant that this torpedo protection layer varied from 4.5 meters thick at its widest point to 2.1 at its narrowest. Torpedo nets provided some added protection while at anchor, but could not be used in open seas.