Eendracht-class cruiser (as designed pre-war)

[YourChair]

Does anyone have:
- general plans and armor scheme of the Eendrachts. For the armor, the correct figures seems to be 100mm belt of unknown height and length closed by 60mm traverses at the end barbettes, with 75mm armor extending beyond the citadel on the sides for an unknown distance, topped by a 25mm deck. I read that: "The armor was supplied by the German company Krupp AG , the French Marrel Freres and the English Colvilles Ltd." Assumedly the side armor is of German manufacture, but I'm not sure if this would be the more traditional KC armor (as used in the Ks and Leipzig) or Nurnberg's Wotan Härte. And I'm not sure where the French and British steel was to come in
- information on the ship's armament, mostly in terms of the parameters of the main battery (the 152/53 Bofors gun, eventually named the M42), but also including what torpedoes were to be used
- I remember hearing (forgot where) about a plan to adopt a medium-caliber secondary battery for the Eendrachts, at the cost of dropping the torpedoes if need be. Does anyone know more?
- Definitive information on the KH1/KH2 designs after capture by the Germans -- I've seen both 4x3 150/55 C/28 and 4x2 150/55 C/28 (to be taken from the M-class cruisers), for example
- information on what the relative strengths and weaknesses of the Eendracht design were? I would assume that the fire control and light AA were above average, but 25mm deck armor seems very inadequate, and the ship's general parameters don't seem very impressive compared to an Abruzzi, Fiji, or even a 2x3 2x2 Amphion.
Any other information would also be appreciated!

 

[M. A. Rozon]

A couple of graphics in my files that I though might help. The more detailed one I thought might be of assistance for deck armour placement.

 

[Roodbaard1958!]

National Archive, The Hague, Netherlands, archive 4.MST Inventaris van de bouwtekeningen van schepen van de Nederlandse Marine 1683-1996:

https://www.nationaalarchief.nl/onderzoeken/archief/4.MST/invnr/%401?query=4.MST&search-type=inventory&start=0&searchAfter=1%2C%401

click on 1.2 Stoom- en motorschepen click on 1.21. Kruisers and then from No. 3284 on, 3284=https://www.nationaalarchief.nl/ond...vnr/3284/file/NL-HaNA_4.MST_3284_deelopname01
success

 

[Sanglune]

Does anyone have:
- general plans and armor scheme of the Eendrachts. For the armor, the correct figures seems to be 100mm belt of unknown height and length closed by 60mm traverses at the end barbettes, with 75mm armor extending beyond the citadel on the sides for an unknown distance, topped by a 25mm deck. I read that: "The armor was supplied by the German company Krupp AG , the French Marrel Freres and the English Colvilles Ltd." Assumedly the side armor is of German manufacture, but I'm not sure if this would be the more traditional KC armor (as used in the Ks and Leipzig) or Nurnberg's Wotan Härte. And I'm not sure where the French and British steel was to come in

There are a number of blueprints available online in the Zeeuws Archief and Nationaal Archief. The former doesn't have as much and most of them are duplicates, but here's the links:

Zeeuws Archief:
https://hdl.handle.net/21.12113/0DCDE714EDFF4537908C4AF845C0AF01
Nationaal Archief:
https://www.nationaalarchief.nl/onderzoeken/archief/4.MST/invnr/%401~1.2~1.2.21
(the preliminary designs can be found under "Voorontwerpen" here.)

A set of armour schemes are displayed under 4.MST 3329 (early) and 4. MST 3330 (later, though does not appear to match the final design yet).
I've appended the latter though downscaled to a quarter the original resolution.

- information on the ship's armament, mostly in terms of the parameters of the main battery (the 152/53 Bofors gun, eventually named the M42), but also including what torpedoes were to be used

The armament I am still in the process of researching. However it is known to have been an autloading system with 60° elevation. From a drawing on maritiem digitaal (appended) and post war discussion it can be deduced it was a single-piece loading system. When the war broke out the Swedes took over two unfinished triple turrets, which they've incorperated in their own cruiser designs together with newly built twins, gaining the Swedish forces designation M/42 (which as far as I know can differ from the Bofors designations). Their firing tables from 1949 note a 46 kg shell being fired at 880 mps. In my recent trip to the Dutch archives I did find a similar although slightly longer but slimmer 150mm Bofors shell for firing exercises. This was given the Dutch designation of №12 and considering the date it leads me to believe that this would be the official designation of the Dutch turrets for the class. It does bear noting however that all prior shells since around 1930 have been 46,25 kg and the standard MV was 900 mps. I highly suspect the muzzle velocity to have maintained the standard 900 mps but no affirmative confirmation has been found.

The AA mounts for 40 mm Bofors would be RPC. It is debatable whether they would receive the same level of treatment for independent FC like the №4 from Tromp, but they certainly would include numerous upgrades over the №3 mount.
Going by De Ruyter, it is likely that the 12,7 mm machine guns would be Colt-Brownings from FN in Belgium with the mountings developed by Solothurn.

Regarding the torpedoes I have not done much research yet. The mountings themselves were originally planned to be quadruples but cut down for weight savings. The pivot was also much further forward but in later itterations it had been moved more centrally and firing angles were increased.

- I remember hearing (forgot where) about a plan to adopt a medium-caliber secondary battery for the Eendrachts, at the cost of dropping the torpedoes if need be. Does anyone know more?

It is possible that information came from me through my domicile known as the World of Warships discord. About two months ago I dug up quite some information from the archives. During early development the design moved from ca. 7600 tons to 8000 tons. The 350 tons increase gave an additional 100 tons to work with for improvements, which included adding two quadruple launchers with foremost pivot. Including 8 reserve torpedoes this would take up 60 tons. It was considered to augment the AA battery with 10,5 cm guns. However since the situation did not necessitate this expansion yet it would not be done. Though 50 tons would be reserved which would be achieved by removal of the torpedo battery.
It is also noteworthy that likewise the Jacob van Heemskerck the fundations of the 40 mm mounts would be sufficiently reinforced to account for future 50 - 60 mm mounts that were not yet available.

- Definitive information on the KH1/KH2 designs after capture by the Germans -- I've seen both 4x3 150/55 C/28 and 4x2 150/55 C/28 (to be taken from the M-class cruisers), for example

I'm afraid I don't have much information from the German side so I will rely on other publications for my information here.
I am not aware of any triple C/28 mount existing so I highly doubt these plans were real. A number of sources do say the twin armament of the cancelled H-class battleship and M-class cruisers would be used for the Kreuzer Holland. However, as far as I know these were to be training cruisers for after the war and thus received little priorisation.

- information on what the relative strengths and weaknesses of the Eendracht design were? I would assume that the fire control and light AA were above average, but 25mm deck armor seems very inadequate, and the ship's general parameters don't seem very impressive compared to an Abruzzi, Fiji, or even a 2x3 2x2 Amphion.

The Eendracht overall would be a solid ship. It had a contract speed of 33 knots without forcing which would most likely mean a delivery top speed of a good 34 knots. An exact comparision would be difficult as standards for measurement differ across time and place.
The armour would not be exceptional but a 20 mm caisson, 75 mm belt armour and 30 mm citadel deck armour would be suffucient for most threats that one could proportionally expect.
Her firepower, meanwhile, would be on the strong side thanks to the autoloading of her main battery and there being a good number of barrels.

Her main drawbacks would be the lack of a unit-system for the machinery and the lack of a dedicated secondary battery. Without a secondary battery she would have to fire starshells from one of her main guns. Though this is not the worst, it does bring her down to 8 guns during night fights. The torpedoes, in my opinion, are also more of a vurnerability than a boon.

 

[YourChair]

Thank you Sanglune! Excellent work as always.

A set of armour schemes are displayed under 4.MST 3329 (early) and 4. MST 3330 (later, though does not appear to match the final design yet).
I've appended the latter though downscaled to a quarter the original resolution.

So the final scheme seems to be:
Side armor
- 75mm side from around frame 2 all the way to frame 92, and it seems like 50mm from frame 93 to 107. This is around 87.5% of the ship's length, which makes even Hipper look inadequate. This armor also stretches well below the waterline, and is closed by a 60mm bulkhead fore and a 30mm aft.
- bow armor extending from the belt is 15mm. No clue what "onderkant hurdpanster" is (bottom hurdarmor? what is hurd? does this refer to being below the upper side armor?), but assumedly this is some intermediate steel between true armor steel for the belt and shipbuilding steel.
- stern armor seems to be 60mm for the remaining section
- upper side is 50mm in the machinery area, and 20mm everywhere else. The exception is the bow forward of the A turret, which is 13mm
- forecastle is 15mm until the forward turrets, where it is 13mm. The armor ceases forward of the A turret.
- 30mm torpedo bulkhead up to the citadel deck, serving as a splinter bulkhead
Deck
- aforementioned main (citadel) deck (note that the citadel is practically the entire length of the ship) is 30mm, and is slightly sloped up to be stepped over the machinery
- upper deck 1 level above is 20mm, decreasing to 10mm under the turrets
Turrets: 125mm face, sloped inward at around 30 degrees, 30mm sides, 65mm rear, 50mm roof
Barbettes are 75mm circles all around, decreasing to 60 all around under the upper deck, and to 20mm under the main deck (seems like pretty standard practice, although perhaps weight could have been saved in places unlikely to be hit, as was done in some other navies)

Other:
12.7mm ammo stored in 15mm-armored boxes above the citadel
aft control stations are 15mm everywhere
forward control stations are 30mm in general on all sides, except 15mm CT roof, 20mm CT floor, and 20mm bridge roof

I am not aware of any triple C/28 mount existing

It was planned for the 150mm versions of the Hippers, among other things