WesWorld

I found this little monster in the submarine board of the old Warships1.com. I though she´d be worth a try, and I simmed her. So what do you think about her? can you imagine these little ones serving in WW2? Perhaps converted into a submarine aircraft carrier? Just wondering... She´s from Norman Friedman's "US Submarines Through 1945: An Illustrated Design History".



20000 ton, Submarine Cruiser laid down 1920

Displacement:
19.272 t light; 20.000 t standard; 22.000 t normal; 23.511 t full load

Dimensions: Length overall / water x beam x draught
625,01 ft / 625,00 ft x 72,00 ft x 40,74 ft (normal load)
190,50 m / 190,50 m x 21,95 m x 12,42 m

Armament:
4 - 12,00" / 305 mm guns (2x2 guns), 864,00lbs / 391,90kg shells, 1920 Model
Breech loading guns in turrets (on barbettes)
on centreline ends, evenly spread
Weight of broadside 3.456 lbs / 1.568 kg
Shells per gun, main battery: 150
14 - 21,0" / 533,4 mm submerged torpedo tubes

Armour:
- Belts: Width (max) Length (avg) Height (avg)
Main: 6,00" / 152 mm 305,00 ft / 92,96 m 10,00 ft / 3,05 m
Ends: Unarmoured
Main Belt covers 75 % of normal length

- Gun armour: Face (max) Other gunhouse (avg) Barbette/hoist (max)
Main: 6,00" / 152 mm 1,00" / 25 mm 2,00" / 51 mm

- Conning tower: 6,00" / 152 mm

Machinery:
Oil fired boilers, steam turbines plus diesel motors,
Electric cruising motors plus geared drives, 4 shafts, 51.730 shp / 38.591 Kw = 25,00 kts
Range 20.000nm at 10,00 kts (Bunkerage = 3.599 tons)

Complement:
903 - 1.174

Cost:
£3,051 million / $12,202 million

Distribution of weights at normal displacement:
Armament: 432 tons, 2,0 %
Armour: 1.011 tons, 4,6 %
- Belts: 810 tons, 3,7 %
- Torpedo bulkhead: 0 tons, 0,0 %
- Armament: 99 tons, 0,5 %
- Armour Deck: 0 tons, 0,0 %
- Conning Tower: 102 tons, 0,5 %
Machinery: 1.809 tons, 8,2 %
Hull, fittings & equipment: 11.520 tons, 52,4 %
Fuel, ammunition & stores: 2.728 tons, 12,4 %
Miscellaneous weights: 4.500 tons, 20,5 %

Overall survivability and seakeeping ability:
Survivability (Non-critical penetrating hits needed to sink ship):
14.917 lbs / 6.766 Kg = 17,3 x 12,0 " / 305 mm shells or 2,2 torpedoes
Stability (Unstable if below 1.00): 1,02
Metacentric height 3,2 ft / 1,0 m
Steadiness - As gun platform (Average = 50 %): 0 %
- 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: 0,420
Length to Beam Ratio: 8,68 : 1
'Natural speed' for length: 25,00 kts
Power going to wave formation at top speed: 41 %
Trim (Max stability = 0, Max steadiness = 100): 50
Bow angle (Positive = bow angles forward): 5,00 degrees
Stern overhang: 0,00 ft / 0,00 m
Freeboard (% = measuring location as a percentage of overall length):
- Stem: 0,10 ft / 0,03 m
- Forecastle (30 %): 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: 0,10 ft / 0,03 m
Ship tends to be wet forward

Ship space, strength and comments:
Space - Hull below water (magazines/engines, low = better): 74,6 %
- Above water (accommodation/working, high = better): 0,6 %
Waterplane Area: 26.601 Square feet or 2.471 Square metres
Displacement factor (Displacement / loading): 175 %
Structure weight / hull surface area: 290 lbs/sq ft or 1.417 Kg/sq metre
Hull strength (Relative):
- Cross-sectional: 2,58
- Longitudinal: 1,83
- Overall: 2,00
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

What a monster!

You missed the AA guns (visible on the second pic from top) - I assume they are 20mm guns?

Seems like she might have a looooong dive time. How long do you think it will take to get that much submarine under water? Without the help of a salvo of 16" shells, that is. 10 minutes? 15?

How to close large boiler uptakes when diving? Even diesel uptakes caused many problems on submarines and leaked water time and again...

As a carrier you can´t use such a vessel - at least not for planes without floats. The ships deck is too low above water to launch and land standard airplanes...

Note to Self: Develop nuclear depth charges.

I never thought this design would be practical, just simmed her out of curiosity. When I mentioned the posibility of using her as a carrier I was thinking on something in the lines of the I-400s but on steroids, removing one or even the two turrets and replacing them with hangars and all the necessary stuff, the I-400s could hold up to 4 seaplanes, 3 ready and one unassembled, I think this one could put about 12-15 seaplanes in the air...

I´m not sure about how much time would she need to dive, I´m not a sub expert, but only shutting down the steam turbines would take a while...

I think this bring outs another question, what would be the maximum practical tonnage limit in your opinion for a sub of this time-frame (20s-30s)?. The biggest subs of that period historically were the british X1 (3000t, she proved to have excellent handling qualities and was a steady gun platform), another one would be the USS Nautilus, V-Class (2700t, long endurance ocean-going vessels with 2 6 in guns), the french Surcouf (3300t) and later during WW2 the I-400s (5200t). Would a 4000-5000t unit be useful? Or even bigger?

I know we´re limited by the treaty to 1500t subs, but if I were in the USN I´d press for bigger ships if the treaty is ever revised. Just take a look to the historical subs of the USN in the 30s-40s, the USN wanted big units for long patrols, especially in the Pacific.

I was never worked in a boiler room aboard ship but had the (unfortunate?) opportunity to spend some time in one at various points during my time in the USN.

They were HOT!!!! and needed a lot of ventilation. You didn't have just the boiler uptakes, you have numerous blowers bringing in cooler air from the upper decks. (You could really feel the heat on the other side of the bulkhead)
I can't image what it would be like to operate a steam plant in a submarine hull. You would need a lot more air circulation than would be considered acceptable in a typical submarine design.

Boilers take time to build pressure. You just don't turn a switch and have instant power as with diesel engines.
Did these ships have an auxillary diesel to power the ship while surfaced before the boilers where ready.

Given the size of the submarine, was there any real advantage in steam. Couldn't diesel engines achieve the same performance? It wasn't going to be a racehorse on the surface or submerged.

This ship would make an interesting raider. Could you image what would happen if it surfaced of New York or LA during the early days of WW-2 and lobbed a few shells inland??????

Ultimate submarine? This Italian project from 1919 has 6x381mm guns and 8x120mm. She is 22,000t and is armoured. She uses the Pugliese TDS and can do 18knts.

RA - your pic isn't showing.

http://xoomer.virgilio.it/bk/NWS/Regia_M…ltri/index.html

Top right hand stide.

I think the Italian designs are not 'true' submarines - at best, semi-submersible. They were designed to ballast down to reduce their above water appearance, but never to completely submerge - unless they got hit.
(One interesting approach to a stealthy warship somewhat ahead of its time....)

I saw this in NavWeaps.com and thought it was interesting enough to remember this thread. That is the British Submarine M-3 sporting a 12 inch 40 caliber cannon...Mark IX.

There were also M1 and M2. M2 carried a floatplane hangar. M1 had a 12"/40 gun and was lost in the channel after being rammed by a Swedish freighter.