Why did the Germany navy stick to dual-turrets for the Bismarck-class?

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thestor
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Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by thestor » 27 Dec 2016 17:58

In both world wars, the German navy mostly used dual-turrets on battleships, Scharnhorst and Gneisenau are the only exception I can find. With Bismarck and Tirpitz, it was back to dual-turrets. To be precise, four two-gun turrets, making for eight guns. Now, had the Kriegsmarine used triple turrets, they could have had nine guns in one turret less, like with the mentioned Scharnhorst and Geisenau. I recently started reading "Battleships of World War II" by Willian H. Garzke jr., Robert O. Dulin jr. and Thomas G. Webb, and regarding the French Richelieu-class, it was claimed that the weight reduction from eliminating a turret were considerable, said saved weight could naturally be used for armor or machinery.

Given that by WWII, the British and the French built quadruple turrets, and that triple-turrets had been build by almost everyone, even Austria-Hungary, I wonder why the German navy stuck with dual-, instead of triple-turrets. Can anyone enlighten me?

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by kgvm » 05 Jan 2017 21:22

I assume this was done to reduce the damage in case a turret is hit.
If you have four double turrets, you lose only 25 % of your firepower, if you have two four-gun turrets, it's the half!

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Felix C » 08 Jan 2017 13:20

I recall the writers above also mention additional barrels per turret meant wider magazines meaning more beam and different hull shape,(the ships were ocean raiders so steaming radius was important and so hull shape/design would be important) more complicated cradles and then there is the dispersion issue.

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Tomg44 » 10 Jan 2017 12:22

A possible explanation is that the Germans were trying to deceive other navies. They could bluff and bluster their way through with 2 gun turrets. 4 guns would have suggested a vessel in excess of the treaty limits, and greatly increased the alarm in the British and French navies (The treaty is the Washington Naval Treaty of 1922 which limited battleships to 35,000 tons).
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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Terry Duncan » 12 Jan 2017 18:02

The Germans had a working design for a twin 15" gun, so it only needed updating, whilst a 15" triple would be a new beast and take longer to get built, so the twin makes sense, although an attempt could have been made to scale up the 11" triple it may have not proven successful as this isnt always a foolproof method - though I am not too sure why. Other than that, twins allow for greater redundency as others have pointed out, in that fewer guns are lost if a turret is hit. Twins also allow for a slimmer hull form, and thus a higher speed, which is one reason the WWI Japanse ships stuck with twins for all their battleships. Triple turrets allow greater concentration of protection, and fewer weaknesses in the deck and it is pierced by three and not four barbettes, but do have a slower rate of fire as one gun (usually the center gun) is always crowded due to breach operation when loading, so they make more sense for a design based on heavy concentrated armour and armament, basically a defensive design for a ship. The Germans had less use for that sort of ship as anything they built would need to be able to evade the British fleet, so a speed of 29kts or more would be needed in general (allowing only the older and weaker BC's able to intercept them). A far larger ship would have been needed to avoid those too, so the best blend for what the Germans intended was the set up on Bismarck. They also thought the most likely engagement she would fight would be at close or medium ranges under North Sea conditions, for which she is a very good design indeed. For longer ranges, the design wastes a lot of weight, and whilst difficult to sink, is relatively easy to disable.

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by thestor » 20 Feb 2017 06:47

Thanks for all the answers, one question: one argument for the twin-turrets was, that the ship could be made slimer and therefor faster, yes? However, wikipedia gives the width of the Bismarck-class as 36 meters, broader than any other contemporary ship I found on a quick search. According to wikipedia, they were faster than the lighter North-Carolina-class (0,4 kn) and King-George V-class almost as fast as the Iowa-class and Littorio-class (0,8 kn).

Is wikipedia wrong? If not, how come the Bismarck-class was broader than (somewhat) contemporary battleship-classes with triple or even quadruple (King-George-V-class) turrets? And how come she was faster than or very nearly as fast as slimer battleships?

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Nautilus » 21 Feb 2017 11:30

The Richelieu class was actually flawed, as the French naval architects fully understood the concentration of guns left half of the main battery vulnerable to a single lucky shot. They needed the weight reduction from eliminating a turret, but only because they were bound by Treaty limitations. They built the main turrets with a central armored bulkhead, to save at least half the guns if the turret was hit. The Kriegsmarine high command expected to cheat on Treaty limits anyway, as they had done in the past. So they could afford to fit 4 turrets in place of 3.

Beam was not a consideration, as Bismarck was 9% broader than its closest American counterpart, North Carolina, and at least 14% broader than a King George V. Nearly equal in beam to the much larger Yamato.

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by thestor » 28 Feb 2017 17:28

So, beam width plays little role in a ship's speed?

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Nautilus » 02 Mar 2017 14:52

Length/beam ratio is very important for a ship's speed on a given displacement, but the calculations needed to get the best hull shape are far more complex.

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Janef » 02 Mar 2017 17:39

Just a short remark to the topic, which is related to battleships F and G (BS and TP). This was an ongoing program and the french battleships were the main influence of the design solutions. 34 cm guns in triple or quadruple turrets were considered for quite a while, but Krupp, the only German factory producing super heavy guns brought everything to an old school desision when pointing out the need for extensive design work on the guns, and the need to more or less abolish the QF gun design (Schnelladekanone) which the German navy had held high, while the french, british and US navies went for BL type guns with bagged powder charge. A change in gun ammunition system would delay the gun production, a delay the the German navy could not accept. They stuck to the established and proven QF design from pre WW I. For further reading I recommend Paul Schmalenbach Die Geschichte der deutschen Schiffsartillerie, as well as quite a number of documents dealing with the issue at the Bundesarchiv in Freiburg. (RM 7)
The number of turrets were also determined with the German firing tactics in mind. A ship with four turrets were to divide its firepower in two parts, firing alternative salvos. In stead of on 4 turret salvos every 25-30 seconds, they fired 2 turret salvos at 15 second intervals, at the same target or at two different targets. This way of conducting gunnery battles also had great influence on the desision of multiple tutrrets.
JEF

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Nautilus » 03 Mar 2017 12:16

Due to the same German firing tactics, gun laying and loading machinery had been designed for a very quick rate of fire, practically the record for any 15-16 inch gun in history: 1 shot each 20 seconds in ideal conditions. On average, they were rated for 1 shot each 26 seconds.

Only the Richelieu class guns came close, at 25 seconds, but also only under ideal conditions. British BL 15 inch Mark I of the Queen Elizabeths could be loaded at more than one elevation and fired 1 shot each 30 seconds, as the American 16-inch / 50-caliber Mark 7 did. All other heavy gun designs assumed a slower rate of fire, which they sought to compensate by heavier shells or higher muzzle velocity to make the shell more destructive.

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Terry Duncan » 19 Mar 2017 05:01

thestor wrote:So, beam width plays little role in a ship's speed?
It plays a role, but there is also length and draught to take into account. If you look at Bismarck you will see she is a relatively shallow draught hull for the weight, needed so she could pass through the Kiel Canal and use all German naval harbours, this was achieved by increasing the beam greatly compared to similar foreign ships. It is the section of the hull in contact with the water that is important, so there is a trade off between shallow and deep draught that can get similar speeds and efficiencies. A wider hull also allows for better torpedo defence, but also tends to make the ship stiffer in a turn, losing speed in a turn far more than a deeper draught hull usually.

With regards to the quadruple turreted ships, this allowed for a shorter armoured citadel, cutting down on the weight the armoured deck imposed on a design. The designs with turrets clustered together, like the I3/G3/H3/N3/Nelson/Richelieu/Dunkerque designs, allow for very short areas of the hull to be protected by the very thickest armour (often with a very heavy forward transverse bulkhead too) with the magazine areas being enclosed in this area, whilst the machinery was protected by a reduced scale or armour (a hit on the machinery tends not to make the ship do 'the big firework' impression as does one on a magazine), as well as allowing for a slimmer hull form overall as once again, the maximum beam is centered on the area of the turrets rather than much of the middle of the ship as in conventional designs. Such designs make excellent sense where there are limits imposed on a design, be it weight limits (Richelieu) or the need to fit in existing docks (the I3/G3 designs came about due to the inability to dock the conventional K3 design anywhere at all!), but obviously in general they are slightly inferior to conventional designs not constrained by such artificial limits.

thestor
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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by thestor » 14 Apr 2017 09:32

(I really have to come here more often) What about ships unrestricted in planning or construction, be it from treaties or harbor facilities? Even if there is no treaty limit to observe, the weight-saving of the quadruple-turrets could be used for something practical, no?

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by Terry Duncan » 18 Apr 2017 02:40

thestor wrote:(I really have to come here more often) What about ships unrestricted in planning or construction, be it from treaties or harbor facilities? Even if there is no treaty limit to observe, the weight-saving of the quadruple-turrets could be used for something practical, no?
The main benefit is in the concentration of guns that allows thicker armour to be placed over a smaller area, and for fewer holes cut through the main deck to house them. Because the quad turrets are so wide themselves, they need to be a fair way back in the hull in order to accomodate them if a high speed is also desired. There is one interesting anomoly to this that sadly was not built to the initial plan, and that is HMS Belfast, which was originally planned to mount 16 x 6" guns in 4 quad turrets. The turret mounting was proving troublesome in tests iirc, and with a way likely approaching it was decided to mount the already existing and successful triple mounting. The only visible sign of this on the ship we see now is the unusual placement of Y turret standing one deck higher than the stern deck. Apparently the deck was cut down here compared to the standard Town design to that point in order to save on weight. Sadly I have never seen any official representation of Belfast with the 16 guns fitted, or indeed even a mock up on one of the many naval forums that feature many unbuilt designs or even fantasy ships.

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Re: Why did the Germany navy stick to dual-turrets for the Bismarck-class?

Post by critical mass » 13 Jun 2017 17:29

The firing procedure adopted by the KM actually preferred four dual turrets as the ideal setup for controll of batteries in a gunnery engagement.

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