Building a patchwork battleship

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
Mostlyharmless
Member
Posts: 211
Joined: Wed Jul 22, 2009 10:45 pm

Building a patchwork battleship

Post by Mostlyharmless »

Freedonia wants to build a class of battleships from January 1937 but there is a difficult political problem. Freedonia takes its neutrality very seriously. Thus the government insists that each of the battleship producing nations, Britain, France, Germany, Italy, Japan and the USA, should contribute some significant features to the design. Thus they have set up their design office to ensure that the design can be optimized without giving away too many of each nation’s secrets. What should the design look like?

I decided to start from the bottom by employing Japan to design most of the hull form except that the British can improve it by making the stern more obviously transom.

Of course, I didn’t intend to let the Japanese anywhere near the rudder(s) but what to use? The British choice of a single rudder is simplest, cheapest and gives lowest resistance but is obviously vulnerable as seen in the case of the carriers Akagi or Intrepid. Two rudders close together doesn’t help as seen with Bismark but were the two on North Carolina far enough apart at 24 ft.? Is the Littorio arrangement compatible with a transom stern?

We might use German ST52 steel for the hull because it is weldable and cheaper than American STS whilst the British DW steel might not be ready.

Obviously, I would like to use American machinery but should we use French machinery because frankly, what other French equipment is worth including? Can we at least improve the subdivision?

And so on up to the optics at the top….
Mostlyharmless
Member
Posts: 211
Joined: Wed Jul 22, 2009 10:45 pm

Re: Building a patchwork battleship

Post by Mostlyharmless »

As no one has stepped forward with a complete plan, I will take the next step of considering defence against torpedo damage. If we, possibly unfairly as it was hardly tested, exclude the Pugliese System, we can chose between the American, British and German systems of where to place liquid. Possibly the easiest way to get an overview of the issues on the internet is to look at the American report on the Japanese work at http://www.fischer-tropsch.org/primary_ ... S-01-9.pdf. There may have been a slight Japanese preference for the Bismarck arrangement for contact explosions but having the liquid outboard might reduce the effect of near missing bombs.

The USN seemed happier with the North Carolina and Montana designs compared to the South Dakota and Iowa designs. Mixing armour against shells with anti-torpedo defence seems to be dangerous, especially as illustrate by Yamato http://www.spacecruiseryamato.com/ijn/a ... /heel.html.

The Japanese tests suggest that welding could greatly improve protection and that the type of steel used was important. Their own D steel (also used by the RN) was inferior to their homogeneous armour. Germany is the only country that developed a steel, Wotan Weich, specifically for anti-torpedo bulkheads but ironically this was riveted rather than welded in the Bismarck Class despite almost all other armour being welded. It is also not clear that it was better than other armour steels.

The other issue is whether we use a wide torpedo defence system or whether we use the British method of having a narrow system with "sacrificial" compartments inboard. Bismarck used a combination of a wide system at the engine rooms, 5.4 metres, and a much narrower system going down to only 3 metres between the outer hull and the 45 mm Wotan Weich bulkhead at the turrets together with an additional 20 mm bulkhead protecting the magazines with refrigerated food stores in between. The King George V Class also lacked the sacrificial compartments at the engine rooms and had narrower voids added to partially replace them.

After studying these questions, Freedonia plans to try to develop welding techniques for the torpedo defence system. The choice of material depends on achieving satisfactory welding but the USN's STS may be chosen unless welded Wotan Weich proves superior in tests. They intend to use the space advantages of using American or French machinery to allow them to use a narrow primary system with a 45 mm bulkhead at about 3.7 metres from the outer hull and an inner 20 mm bulkhead over the length of the citadel. Hopefully, this will allow them to fit useful but not individually critical equipment in approximately 2.5 metre wide rooms, accessible only via scuttles, between these bulkheads.

As we have not yet chosen the arrangement of the armament, we don't know how long the citadel will be. However, the fate of Musashi has convinced us that we need something like Bismarck's or King George V's length of torpedo defence system. King George V had deck armour extending forward on the lower deck beyond the main armour belt to create a longer raft. There will probably also need to be some deck armour aft to protect the screws and rudders. Extensions may possibly help to avoid discontinuities near the magazines.
Mostlyharmless
Member
Posts: 211
Joined: Wed Jul 22, 2009 10:45 pm

Re: Building a patchwork battleship

Post by Mostlyharmless »

Well I have had the first suggestion as a private message but it only proposed that I should use the French wine store. Thus I intend to continue upwards to the belt. The British and Germans both made excellent face hardened armour but this seems the best opportunity to employ Italian materials. The faces of the Littorio turrets were 38 cm thick, so Italy could manufacture armour up to that thickness although Littorio's belt did not use anything thicker than 28 cm.
Freedonia is still pondering the arrangement of belt and main armour deck with the examples of vertical topped by a deck (King George V, Lion and Vanguard), vertical with a scarp (Scharnhorst, Bismarck, H39), external inclined (Littorio, North Carolina, Yamato and Montana) or internal inclined (Nelson, Richelieu, South Dakota and Iowa).

Before deciding, they are asking clarification of the Germans as to how they are able to resist the stresses on the hull with welded armour. They note that almost all the other proposals make a single strength deck out of two layers of steel laminated together, for example 4.75" on 1.25" of class B in the case of Iowa. They speculate that the 5 cm weather deck and the 8 cm main deck of Bismarck interact via their multiple bulkheads to form a single rigid unit. However, they are not sure and require this data before developing the design further.

As we have not yet used too many British features, we are planning to use British 5.25" secondary batteries. Freedonia doubts if any heavy anti-aircraft guns can be really effective over 1939-42 but were impressed by the number of Japanese aircraft that Prince of Wales damaged or shot down with just half the battery working and defective radars.
Mostlyharmless
Member
Posts: 211
Joined: Wed Jul 22, 2009 10:45 pm

Re: Building a patchwork battleship

Post by Mostlyharmless »

Freedonia's designers are still arguing over which decks should be armoured and what armament to use but have recently also focused on the question of redundancy and cost. The British KGV at £7.4 million was less than half the cost of North Carolina (converting at 4.8 $ to the £) or Bismarck (using the official if possibly misleading 2.5 RM to the $). KGV is also roughly half the cost of Yamato but that does scale with displacement.

Riveting was probably still cheaper than the new "high tech" welding and D steel was much cheaper than American STS but also the German and American battleships had much more redundancy. Bismarck's engine rooms remained in contact through Bismarck's final battle until the order was given to scuttle whilst Prince of Wales engine rooms were out of contact after the first Japanese torpedo hit. Bismarck's aft main armament fire control had essentially the same capability as its main fire control. Both American and German battleships have much more pumping capacity and electrical power than a KGV and use AC rather than DC. American ships had more air conditioning and were more comfortable in hot weather as well as better for electronic equipment.

Freedonia's designers feel that the question of cost requires some knowledge of what total budget is available as it would be silly to be able to afford one and a half ships. There is also the cost of manning and running the ships to consider as well as the need for docks large enough to accept them, which will increase the cost of a Yamato significantly.

After seeking guidance from political authorities, the designers have been instructed to build a "35,000 ton" battleship which is not obviously bigger than Bismarck or Littorio (which designs are fortunately known as they have received presentations). Thus the length and beam will be less than Bismarck's since those have been released. Note that Freedonia has not signed any treaties but does not want to appear disruptive. Building more than two ships would also be considered undiplomatic, so the designers have been instructed to spend "sensible" sums to increase the battleship's capabilities.

Another issue is that only Germany can provide radar sets in significant numbers for 1939. Britain may be able to compete for ships completing late in 1940 whilst the USA can supply such equipment from perhaps the end of 1941. Thus the designers need a commissioning date before choosing a supplier. A similar but more esoteric issue concerns the codes used for signals. The USN's ECM II was the best cipher machine of WW2 and we know the first machines had arrived at Pearl Harbor but not been taken aboard any battleships on December 7th 1941.
Thorsten Wahl
Senior Member
Posts: 919
Joined: Mon Apr 27, 2009 4:17 pm

Re: Building a patchwork battleship

Post by Thorsten Wahl »

With regard to horizontal protection,

There are several types of attacks
AP-bombs
General purpose-bombs (large HE-capacity(
AP-shells (incl.semi AP)
HE-shells

The different arrangements perform different against different types of attack.
Ballistic protection splitted or not

The same for attack against vertical protection.



Speed versus protection-->can you keep the enemy distant.
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
Thorsten Wahl
Senior Member
Posts: 919
Joined: Mon Apr 27, 2009 4:17 pm

Re: Building a patchwork battleship

Post by Thorsten Wahl »

Double
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
Mostlyharmless
Member
Posts: 211
Joined: Wed Jul 22, 2009 10:45 pm

Re: Building a patchwork battleship

Post by Mostlyharmless »

Freedonia's designers haven't reported back as quickly as their politicians helped but that was predictable. Making a detailed design of a battleship to be laid down in January 1937 turns out to be quite difficult even without the requirement to use ideas and materials from six different countries. However, progress has been made. Freedonia's unique advantage of having access to the detailed designs of Littorio, Bismarck and especially Yamato has convinced its leaders that the 35,000 ton limit on battleships will not be considered important by 1941-2 when their ships will be in service. As mentioned, they do not want Freedonia to be blamed, however unfairly, for the breakdown of the treaty regime and insist that the length and beam of their ships are shorter than the length and beam of Bismarck. Fortunately, the choice of a hull form based on the Yamato design will allow a greater displacement than Bismarck if desired due to the higher block coefficient.

They have decided to scale the Yamato hull from 267 metres overall to 245 metres which scaled the 38.9 metre beam down to 35.6 metres. That would still give a 61,000 tons full load displacement and reducing the length would worsen the wave resistance even if the shape was preserved. Thus they hope to slim the hull down to 33 metres, which brings us down to Iowa's full load displacement of 56,000 tons. The stern will change more significantly but that requires its own study.

As mentioned earlier, the designers have decided to use machinery very similar to that of Richelieu and Jean Bart. During their visit to France, they were shown an initial sketch for Gascogne and decided that they liked its main armament arrangement. However, they were doubtful of the effectiveness of the French 38 cm guns and shells. They have therefore been considering related alternatives and have decided to buy from Japan the 45 caliber Type 94 40 cm gun with its triple turret and associated machinery. Although two of these turrets will only throw six shells in a broadside, they will have reasonable armour penetration at most ranges, especially if they design shells based on the German L 4.4 models. The announcement that the ships will only carry six 40 cm guns will hopefully sooth any fears that Freedonia's ships will greatly exceed treaty dimensions.

Unfortunately, the naive expectation of some of Freedonia's designers that it would be possible to build significantly lighter versions of those turrets by using Italian face hardened armour were disappointed as the armour is not a huge fraction of the very substantial rotating weight of the Japanese turrets, 2,470 long tons or 2,730.2 tons if we include the 60 rounds per gun stored within the barbette. Japan appears to have gone to the opposite extreme from the Royal Navy's Nelson Class by achieving reliability at the expense of using very heavy machinery. However, a useful 100 to 150 tons per turret might be saved using Terni Cermented without making the turrets too vulnerable. The storage of 60 rounds per gun in the barbette saves significant magazine volume but requires more powerful and heavy machinery. It also means that these ships can either fight enemy battleships or bombard land targets but that the choice must be made before sailing [editor's note: this may be another reason why Yamato was never seen off Guadalcanal].

Before continuing, we should mention that the visit to France also introduced Freedonia to a method for making difficult decisions https://books.google.co.uk/books?id=l2n ... ds&f=false (darts may be used instead of cards as in the BBC adaptation) which will hopefully speed up the design process.
Mostlyharmless
Member
Posts: 211
Joined: Wed Jul 22, 2009 10:45 pm

Re: Building a patchwork battleship

Post by Mostlyharmless »

Freedonia's designers started from the detailed designs for Richelieu and were confident that they could use its machinery in their Yamato derived hull. Richelieu machinery seems to have been placed in only four rooms with 3 boilers in the first and third and two sets of turbines in the second and fourth rooms. Everything fitted in a rectangular box 51.2 metres long, 16.7 metres wide and about 11 metres high. The rooms for the boilers were about 11 metres long and the engine rooms around 15.1 metres long. At first sight it seems easy as the floor area is only 859 square metres compared to 1438 square metres for Yamato. However, the designers of Yamato compressed its machinery into a length of only 43 metres at the expense of making it much wider and weakening the torpedo defences.

Freedonia's solution was to have the turbines for two outer shafts side by side but in separate rooms nearest the stern and to place the two turbines for the inner shafts in separate rooms one in front of the other forward of this. Hopefully, the gearing can be placed in its own rooms but in any case a small room can be placed aft of the inner turbines. The length of the machinery is defined by the 15.1 metres outer turbine rooms plus three 11 metre boiler rooms to port and starboard of the forward engine rooms. Thus the total length of this machinery is 48.1 metres. The maximum width is that of an engine room, 8.4 metres wide, and two boiler rooms, 5.6 metres wide, which is 19.6 metres.

Given Freedonia's plans to have a torpedo defence system of 3.7 metres plus 2.5 metres on each side, the beam of our battleship has to be 12.4 plus 19.6 metres or 32 metres but the designers are willing give themselves an extra metre as a beam of 33.0 metres is the same as that of several other battleships and should not cause any diplomatic problem. This will hopefully allow any rearrangements forced by the increased subdivision to be accommodated and allow for flexing of the inner bulkhead under explosive loads.

However, there may still be problems if we would like to have magazines for some of the secondary armament amidships. These will be occupying the same space as the boiler rooms and thus we might add 7.9 metres to the length of the machinery section. This increases the length of the machinery section to 56 metres, which is unfortunately 4 metres longer than that of Richelieu and a massive 13 metres longer than Yamato. However, it is dwarfed by the 94 metres long machinery space of Bismarck, which also included magazines and equipment such as electrical generators. One effect of adding the magazines for the secondary armament is to drive us towards a two funnel design.

As the inner turbine rooms only occupy 30.2 metres, we have 11 metres by 8.4 metres of space to fit equipment needing steam for power such as electric and hydraulic power generation. The outer sacrificial compartments can be used to generate most of the required electric power using Diesel generators so that there are no steam pipes going through the inner bulkhead.

There is another consequence of using French machinery as it is very close to 11 metres tall. Thus if we have a 1.7 metre double bottom and an 11 metre draught at full load, the deck above the machinery is 1.7 metres above the full load waterline, which starts to constrain the choice of armour schemes. For example, some USN battleships late war had the main armour deck 5 ft. 7 in. above the full load waterline and had a deck between the machinery and the MAD, which makes their scheme hard to apply.
Thorsten Wahl
Senior Member
Posts: 919
Joined: Mon Apr 27, 2009 4:17 pm

Re: Building a patchwork battleship

Post by Thorsten Wahl »

French and Italian powerplants were comparatively light and compact.
cons.
reliability under battledamage is doubtful (redundancy)
the powerplants were less effective in steam consumption
is range a must?

if range is the primary consideration how about german V-Motor

12 x 15000 WPS =180000 WPS about 150000 required for 30 kn
weight ~22 kg/WPS pure motorweight
----->~4000 t
+1000 t auxillaries
individual size of each motor space
lenght 13,5m
height 7,1 m
width ~ 6,0 m

+ 3-4 transmissions depending on No of screws
id prefer a 4 screw arrangement becaus of the turning moment of the inner screw
additionally it places the two rudders in the center of the waterstream of the inner screws.

lenght ~7,5m
widht same as motor
height lower

these motors should b unbeatable fuelefficient compared to steam turbines
< 0,22 - 0,25 kg/WPS at maxpower

------------>and the external motors protect the internal ones against damge from the side

sample Admiral Scheer steamed from South Afrika to France with one filling of fuel (~3000 t)
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
Mostlyharmless
Member
Posts: 211
Joined: Wed Jul 22, 2009 10:45 pm

Re: Building a patchwork battleship

Post by Mostlyharmless »

Using German diesels is an interesting idea with very good subdivision and fuel economy. Freedonia rejected it because the machinery for the H39 Class might not be ready in January 1937 and diesel machinery is generally installed very early during ship building. They also wanted to buy a significant fraction of the ship from France and the French machinery, although operating at quite conservative pressures and temperatures, was powerful for its weight and volume due to its production of large volumes of steam. The arrangement of the machinery from Richelieu was rejected because it was not sufficiently subdivided and an alternative proposed above which would hopefully have greater redundancy. However, I don't have any evidence that Richelieu's machinery was more susceptible to shock damage that that of other battleships. For example, the mine damage in 1945 apparently wrecked the wine store (possibly with terrible effects on morale) but did not cause a loss of power. Richelieu's published range suggests that the machinery was fairly efficient and certainly much better than Italian ranges.

Freedonia is proposing to have a number of small compartments with diesel electricity generators, approximately 2.5 metres wide, outside the main machinery as inspired by the KGV design https://i.redd.it/t5p33thm7ct81.png. The French ships used the same space to contain partially filled oil tanks and some oil storage might also be possible.
Post Reply