WesWorld

And this one... well I thought it was an interesting idea. It´s based in the german submarine cruisers of WWI, the concept is a big submersible that carrying enough armament could fight in surface with DDs and armed merchant cruisers.

In our timeline the british also tried this concept with the 1925 X1, a 3050t sub, armed with 4 5,2in guns. I´ve tried the concept in a smaller hull and the main armament is in fully enclosed turrets, what do you think? would they be worth the try?

Two subs would be laid down in 1926, X1 and X2 and 2 of the Ls or Js already in service would be decommisioned



X1, British Submarine cruiser laid down 1926

Operational diving depth: 210 ft
Emergency diving depth: 336 ft
Crush depth: 525 ft

Displacement:
1.419 t light; 1.500 t standard; 1.975 t normal; 2.347 t full load

Dimensions: Length overall / water x beam x draught
270,00 ft / 270,00 ft x 32,00 ft x 20,00 ft (normal load)
82,30 m / 82,30 m x 9,75 m x 6,10 m

Armament:
4 - 4,72" / 120 mm guns (2x2 guns), 52,58lbs / 23,85kg shells, 1926 Model
Breech loading guns in turrets (on barbettes)
on centreline, evenly spread
4 - 0,79" / 20,0 mm guns (2x2 guns), 0,24lbs / 0,11kg shells, 1926 Model
Anti-aircraft guns in deck mounts
on side, all amidships
Weight of broadside 211 lbs / 96 kg
Shells per gun, main battery: 350
8 - 21,0" / 533,4 mm submerged torpedo tubes (6 forward, 2 aft, 14 torpedoes)

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2,00" / 51 mm 1,00" / 25 mm 1,00" / 25 mm

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 2.795 shp / 2.085 Kw = 16,00 kts
Range 8.890nm at 15,00 kts (Bunkerage = 855 tons)

Complement:
147 - 192

Cost:
£0,291 million / $1,166 million

Distribution of weights at normal displacement:
Armament: 26 tons, 1,3 %
Armour: 17 tons, 0,9 %
- Belts: 0 tons, 0,0 %
- Torpedo bulkhead: 0 tons, 0,0 %
- Armament: 17 tons, 0,9 %
- Armour Deck: 0 tons, 0,0 %
- Conning Tower: 0 tons, 0,0 %
Machinery: 89 tons, 4,5 %
Hull, fittings & equipment: 886 tons, 44,9 %
Fuel, ammunition & stores: 556 tons, 28,1 %
Miscellaneous weights: 400 tons, 20,3 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1.252 lbs / 568 Kg = 23,8 x 4,7 " / 120 mm shells or 0,5 torpedoes
Stability (Unstable if below 1.00): 1,04
Metacentric height 1,0 ft / 0,3 m
Steadiness - As gun platform (Average = 50 %): 1 %
- Recoil effect (Restricted arc if above 1.00): 0,00
Seaboat quality (Average = 1.00): 0,00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0,400
Length to Beam Ratio: 8,44 : 1
'Natural speed' for length: 16,43 kts
Power going to wave formation at top speed: 37 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 10,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 0,00 ft / 0,00 m
- Forecastle (20 %): 0,10 ft / 0,03 m
- Mid (50 %): 0,10 ft / 0,03 m
- Quarterdeck (15 %): 0,10 ft / 0,03 m
- Stern: 0,10 ft / 0,03 m
- Average freeboard: 0,09 ft / 0,03 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 80,9 %
- Above water (accommodation/working, high = better): 0,7 %
Waterplane Area: 5.029 Square feet or 467 Square metres
Displacement factor (Displacement / loading): 245 %
Structure weight / hull surface area: 112 lbs/sq ft or 547 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 2,27
- Longitudinal: 2,04
- Overall: 2,10
Hull space for machinery, storage, compartmentation is excellent
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

The Submarine X1 carried 4x5.2" guns and was to be able to fight destroyers at 5.000yds.

There were a few German projects for U-boats with 4x150mm guns.

Gravina, does Britain still have the M-Class submarines? M1 and M3 were built with 1x12" gun but M2 had a hangar for aircraft.

Nope, scrapped because of the treaty, they were too big.

It's an idea I think could easily have been 'played with' more in RL during the interwar period - and should lead to some interesting counters (armoured DDs?)...

I like em, all though I'd make em bigger.

I like her. She looks a little 'Italian' (I thinking of the 1930's big RM subs).

I prefer to put my large sub allocation into enlarged 'R class' subs but then Greece doesn't have any 'range' requirements to speak of.

Cheers,

With a steadiness of 1%, it might be tough to hit anything except at close range, and what if you take a hit through your pressure hull? Can you dive the boat after that?

Without those basins fore and aft of her turret she really looks very german. Good drawing.

I agree with the others that heavily armed submersibles are very realistic. Just see SORCOUF (sp?) or other subs build in real life.

However, I doubt you can use barbets. I´m pretty sure they´interfer with the internal pressure hull and have doubts if the joint (riveted or wielded) where barbets and internal hull meet won´t crack during a dive.... Not an expert I am, though, but could be a problem.

Regards,

HoOmAn

Quoted

With a steadiness of 1%, it might be tough to hit anything

That's an artifact of how subs are simmed in Spring*, with decks awash ready to dive. In fully-surfaced condition the steadiness would be higher.

Quoted

what if you take a hit through your pressure hull?

The obvious next step is an armoured submarine.

Well, actually the german Type VIIC42 were armored as armor grade steel was used for their hulls.

So I suppose the idea will go on. I´m glad to see you like them. I had my concerns with the barbettes too Hooman... I was not sure about them... I guess I could try the following one, with the guns in deck mounts (enclosed), and the speed increased by 1.55 knots.

X1, British Submarine cruiser laid down 1926

Displacement:
1.419 t light; 1.500 t standard; 1.975 t normal; 2.347 t full load

Dimensions: Length overall / water x beam x draught
270,00 ft / 270,00 ft x 32,00 ft x 20,00 ft (normal load)
82,30 m / 82,30 m x 9,75 m x 6,10 m

Armament:
4 - 4,72" / 120 mm guns (2x2 guns), 52,58lbs / 23,85kg shells, 1926 Model
Breech loading guns in deck mounts
on centreline, evenly spread
4 - 0,79" / 20,0 mm guns (2x2 guns), 0,24lbs / 0,11kg shells, 1926 Model
Anti-aircraft guns in deck mounts
on side, all amidships
Weight of broadside 211 lbs / 96 kg
Shells per gun, main battery: 350
8 - 21,0" / 533,4 mm submerged torpedo tubes

Armour:
- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 2,00" / 51 mm 1,00" / 25 mm -

Machinery:
Diesel Internal combustion motors,
Geared drive, 2 shafts, 3.931 shp / 2.933 Kw = 17,55 kts
Range 8.890nm at 15,00 kts (Bunkerage = 855 tons)

Complement:
147 - 192

Cost:
£0,309 million / $1,236 million

Distribution of weights at normal displacement:
Armament: 26 tons, 1,3 %
Armour: 17 tons, 0,8 %
- Belts: 0 tons, 0,0 %
- Torpedo bulkhead: 0 tons, 0,0 %
- Armament: 17 tons, 0,8 %
- Armour Deck: 0 tons, 0,0 %
- Conning Tower: 0 tons, 0,0 %
Machinery: 126 tons, 6,4 %
Hull, fittings & equipment: 850 tons, 43,0 %
Fuel, ammunition & stores: 556 tons, 28,1 %
Miscellaneous weights: 400 tons, 20,3 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
1.147 lbs / 520 Kg = 21,8 x 4,7 " / 120 mm shells or 0,4 torpedoes
Stability (Unstable if below 1.00): 1,09
Metacentric height 1,1 ft / 0,3 m
Steadiness - As gun platform (Average = 50 %): 1 %
- Recoil effect (Restricted arc if above 1.00): 0,00
Seaboat quality (Average = 1.00): 0,00

Hull form characteristics:
Hull has a flush deck
Block coefficient: 0,400
Length to Beam Ratio: 8,44 : 1
'Natural speed' for length: 16,43 kts
Power going to wave formation at top speed: 42 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 10,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 0,00 ft / 0,00 m
- Forecastle (20 %): 0,10 ft / 0,03 m
- Mid (50 %): 0,10 ft / 0,03 m
- Quarterdeck (15 %): 0,10 ft / 0,03 m
- Stern: 0,10 ft / 0,03 m
- Average freeboard: 0,09 ft / 0,03 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 90,6 %
- Above water (accommodation/working, high = better): 0,7 %
Waterplane Area: 5.029 Square feet or 467 Square metres
Displacement factor (Displacement / loading): 224 %
Structure weight / hull surface area: 107 lbs/sq ft or 525 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 2,36
- Longitudinal: 2,03
- Overall: 2,10
Hull space for machinery, storage, compartmentation is adequate
Room for accommodation and workspaces is extremely poor
Ship has quick, lively roll, not a steady gun platform
Caution: Lacks seaworthiness - very limited seakeeping ability

As for bigger subs... I´ve a doubt, on one hand the treaty states:

Quoted

VI. SUBMARINE

Any vessel designed to be capable of operating in a fully

submerged condition for any length of time, divided into two

categories, as follows:

Sub-category (a): Submarines displacing not more than 2,000 tons

(2,032 metric tons) standard displacement, and

not carrying a gun above the calibre of 5.1

inches (130 millimetres)

Sub-category (b): Submarines displacing not more than 450 tons

(457 metric tons) standard displacement, and

not carrying a gun above the calibre of 4.1

inches (105 millimetres)

And on the other hand we´ve:

Quoted

F. SUBMARINES



I.



No submarine the standard displacement of which exceeds 1,500 tons

(1,524 metric tons) or with a gun whose calibre exceeds 5.1 inches

(130 mm) shall be acquired by or constructed by or for any of the

Contracting Powers.

So... what´s the limit in the bigger subs? 1500 or 2000 tons... I´m a bit confused about this, that´s why I´ve limited my sub to 1500t.

Uh? What the....

Looks like this one escaped us while editing the treaty - and nobody noticed until now! *g*

However, reading it in context it is not entirely weird:

No signatory is allowed to acquire subs larger than 1500ts.

However, subs of category A can be as heavy as 2000ts - provided they were already in existance and owned by a signatory when the treaty was signed. Those could be kept.

The more I think about it the more I think I can remember some discussion with Peng about it. How large were the largest subs of the pre-1920 era (british Ms for example)? Probably that´s why old subs are allowed 2000ts.

Nevertheless new ones are only allowed to be as heavy as 1500ts standard....

Hope this helps,

HoOmAn

The largest ones where the 1880 ton K class, followed by the 1600 ton M class... well, the K class It´s not a great loss, with their problematic steam powerplant, but It would have been interesting to keep around the Ms and see what could be done with them once their 12 in gun was removed.

It´s late now anyway.

Btw, what speed do you think your sub will achieve below surface?

German Uboats made 7,5-9 kn but with that modified turret and those turrets I expect yours to have a much lower speed, probably around 5-5,5kn....

I´m no expert, but I don´t think the underwater speed would drop so much, even with the large superestructure. Just check the numbers of the original 1925 X1, she was a 3000 ton ship yet she achieved 9 knots underwater.

http://members.iinet.net.au/~eadej/x1class.html , there youve info about the original X1

If I had to say a number I guess my X1 maximum speed would be around 7-8 knots.

Honestly, I doubt this to be the case. German WW2-Type VII boats lost ~1kn due to additional AA guns.

Also remember the Germans helped to modify italian boats to allow faster dive times and increase those boats speed and manoverability below surface. A significant reduction of turret size was a critical factor.

In general your design is very similar to the german Type XI U-cruiser project of WW2 which was designed to achieve 7kn once submerged. More on that design can easily be found on the Net.

Note also that the german U139-type U-cruisers of WW1 - which were similar in size and layout to your design - made 7,6kn below surface. Power output of their machinery was 1760hp. The X1 achieved ~9kn on 2400hp.

In the end there is no rule of thumb how to sim speed below surface with SS, IIRC. So if you want a design to make 9kn - so be it. :o)

Hope this helps,

HoOmAn

Always a good source on uboats: http://www.uboat.net/

I never said my X1 would make 9 knots, the original X1 did them, as I said before I don´t think mine would do much more than 7-8 knots (wich is more or less what you point).