This design challenge surfaced on the Discord partially due to Colo's awesome work on the V-boats and partially because I had a "filler" design done as a companion to another ship done for an unrelated challenge. The backround for this sort of "micro AU" will be done on said challenge, so all I will say here is that these subs are acquired as part of an extensive trade deal.

The two CAPITAN SPOERER-class submarines, CAPITAN SPOERER and CAPITAN DEL SOLAR were ordered in 1931 to Kawasaki Dockyard Company, Ltd. as part of a bigger trade deal involving the Empire of Japan and the Republic of Chile, amidst diplomatic protest from both the United Kingdom and the United States. They were based on the Junsen type submarines then entering service with the Imperial Japanese Navy and were intended for long-range patrol and commerce raiders, but they used armament and ordnance purchased in the United Kingdom to maintain commoniality with the rest of the chilean fleet. Enjoying a very long range and on-station time, these submarines could maintain station just outside the mouth of the de la Plata river or keep extensive patrols all along the pacific coast of South America. They would enter service a bit after the three O'BRIEN-class boats and while at first their roles would seem to overlap, the appearance of the CAPITAN SPOERERs would mean that the old and worn out H-class submarines H-2 TEGUALDA and H-3 RUCUMILLA could be taken out of service. After a period of instruction in Japan, the two SPOERERs would sail to Chile, calling port in Manila, Auckland and Papete. They would prove themselves of excellent quality and demonstrate impressive performance, albeit they were notoriously slower to dive and harder to handle underwater than their O'BRIEN stablemates.

Some statistics for nerds:
Displacement
1920 t surfaced
2600 t submerged
Dimensions:
L: 96 m (315 ft)
B: 8.3 m (27 1/4 ft)
D: 4.9 m (16 ft)
Propulsion:
2 MAN Type 2 4 stroke diesels, 5800 shp total, 18 kn
2 electric motors, 2200 shp total, 9 kn
Range:
14,000 nmi @ 10 kn surfaced
80 nmi @ 4 kn submerged
Test depth: 85 m
Complement: 62 officers and enlisted, 10 prize crew during wartime.
Armament:
2xI 4.7"/45 QF Mark IX
1x 12-pdr 20 cwt QF HA Mark IE
8x 21" TTs, 6 fore, 2 aft, 18x Mark VIII Torpedoes



Hope you like it, and as usual, your comments and criticism is most welcome!

Not wholly original but hey ho.



Derived from the large German U-Kreuzers received as reparations following the end of the Great War, the S29 class were an evolutionary upgrade to the basic idea. There were two boats completed in 1926 for service in the far east out of Singapore.
They displaced some 1,950 surfaced and 2,500t submerged, were good for 18 knots on the surface and 9 submerged, had a range of some 20,000nm. Like their German forebears , they were habitable, spacious and very seaworthy. They had the same torpedo battery as the German boats of four tubes forward and two aft but in addition received centreline rotating tubes along the top of the casing for lighter torpedoes to be used in training and against smaller targets not warranting a 'proper' torpedo. Their initial gun fit consisted of a pair of 130mm and guns in an enclosed deck-house forward of the conning tower and a pompom on a raised platform aft of it.
They would remain unaltered for some time before in a heavy upgrade prior to the outbreak of the second world war which saw them receiving a fold-away short-barrelled 40mm Bofors gun to replace the pompom, improved direction-finding equipment, as well as newer engines and batteries.
Both served throughout the second world war to be retired in 1945 and scrapped in 1947, their later duties being primarily orientated toward the transport and deployment of raiding parties against Japanese installations which saw the removal of their main gun and centreline tubes, which in turn were replaced with a heavier complement of AA guns and collapsible boats.

Statistics
Displacement:
-1,950t surfaced
-2,500t submerged
Dimensions:
-L 101.3m
-B 9.42m
-D 5.48m
Propulsion (as-built):
-2x Sulzer diesel engines, ~3,000hp ea.
-2x Sulzer auxiliary generators, ~250hp ea.
-2x electric motors, ~1,250hp ea.
Performance:
-18 knots surfaced
-9 knots submerged
-37,000km @ 10 knots on the surface
-190km @ 4 knots submerged
-Test depth: 95m
Manning:
-6 Officers
-64 Enlisted
Armament (as-built):
-6x 550mm TTs 4 fore, 2 aft (16 torpedoes)
-4x 400mm TTs 4 amidships (4 torpedoes)
-2x 130mm/45
-1x 40mm/39 pompom

Something else from me...



The S-81 class turned out to be the most numerous class of submarines ever constructed by the Galenic Navy with 48 boats being built in three distinct batches (plus minor sub-batches). They were large ocean-going threats designed to be large enough and capable enough to operate alone in the face of an expansionist driven Dayashinan navy without reinforcements from other naval units.
They drew upon previous experience with large boats, namely the 29, 56 and 63 classes all of which were built for deep ocean work. As designed S-81 featured a single gun but this was amended in the design phase to a pair, one fore and one aft of the sail. They would all see service during the Pan-Septentrion War some more extensively than others, eight would be come wartime losses. After the war the remaining vessels were rationalised with the batch one and two vessels being mothballed then scrapped whilst the best of the batch threes were modernised losing their guns and gaining a new sail structure, later they would also be streamlined and quietened giving good service until replaced by newer vessels in the early sixties.

Statistics
Displacement:
-1,550t surfaced
-2,465t submerged
Dimensions:
-L 96.5m
-B 9.2m
-D 5m
Propulsion (as-built):
-4x Paxman diesel engines, ~1,490hp ea.
-2x Paxman auxiliary generators, ~350hp ea.
-4x electric motors geared to two shafts, ~625hp ea.
-2x 120-cell battery banks
Performance:
-21 knots surfaced
-9 knots submerged
-23,610km @ 10 knots on the surface
-180km @ 2 knots submerged
-Test depth: 95m
Manning:
-6 Officers
-54 Enlisted
Armament (all-vessels):
-6x 550mm TTs 4 fore, 2 aft (18 torpedoes)
-6x 550mm TTs 2 fore, 4 waist (6 torpedoes)
-2x or 1x 130mm/50 latterly 130mm/30
-1-2x Bofors 25mm/64 or 40mm/56 depending on batch and date
-2-4x Hispano 23mm or 30mm depending on date

Good evening:

Here is my candidate:


As the main "cruiser" submarine of a Med Sea power, its range is not outstanding, but is the only class able to operate in the open Atlantic Ocean, derived from the dutch O21 class submarine, it was more heavily armed with internal torpedoes, but were dispensed of the external tubes.

1005 metric tons in surface, 1230 submerged.
Length: 78 mts.
Beam: 6.8 mts.
Draught: 4 mts.

The conning tower was much less conspicuous than the contemporaries from french or italian yards.

Machinery was from Sulzer in the form of 4x 1200 HP diesel engines, and 2 Siemens 500 HP electric motors, in 2 shafts.

Max. surface speed was of 17.5 kts. Submerged speed was around 9 kts.

Armament: 8 533 mm tubes, 6 forward, 2 aft (12 reloads).
1 QF 102 mm (25 pounder) LA wet mount gun.
1 twin 20 mm Oerlikon AA.

Crew: 7 officers, 24 petty officers, 30 sailors.

Credits: My starting design was one of the excellent drawing of Darth Panda, and the color scheme was copied from Ian´s North Point Temeraire sub. Cheers.

I123 IJN Interwar Cruiser Submarine for the decisive battle, using the deception of building an overweight sub with large guns the IJN decided they had an opertunity from LNT Article 7 to get more of the 24" LL to the decisive battle....

Designed to run fast on surface then ballast down semi awash for a night attack on the USN main battle line controlled from the range finder above the control tower.

24 (6x4) 24" TT for the type 93 in quad none reloadable turntables on deck for a single salvo at the USN battle line
4 (4x1) 21" TT type 95 reloadable in bow as secondary weapons to save the main salvo
9 (3x3) 25mm AA and 2x MGs as we will need to run on surface to get into position

Commissioned in 35 she and her two sisters then spent the until late 42 preparing for the battle that never came after that they where released to act as transports with the tubes replaced with storage containers for the now isolated island garrisons....


Parts from Darth Panda and PomboCZ IJN subs

My first attempt at a submarine. I am still new to this, so I am not sure what stats to give it.



These large cruisers submarines were ordered by the Montserratian Free People's Navy in the mid 1930's due to increasing tensions with the Marxist Federation.

They were armed with 10 torpedo tubes (6 bow, 4 stern), 2 6" deck guns for surface combat, and 2 20mm Oerlikons for anti-aircraft defense.

Reports suggest that these submarines had an endurance of 100 days, though these reports are conflicting.


Unfortunately this is all that I can give as far as stats go. I am clueless as to how to calculate stats.

here is the result of studies for a large submarine cruiser (even raider cruiser) made by Galeazzi, one of the main italian designers in the interwar period.



Statistics
Displacement:
-3,800t surfaced
-5,275t submerged
Dimensions:
-L 122.5m
-B 10.5m
-D 5.9m
Performance:
-24 knots surfaced
-9.5 knots submerged
-12,000nm @ 10 knots on the surface
-19,000nm @10 knots on surface (overloaded)
-80 nm @ 4 knots submerged
-Max depth: 150m
-Test depth: 200m
Manning:
-12 Officers plus 22 Subofficers
-80 Enlisted
Armament:
-8x 533 mm TTs (20 torpedoes)
-4x 152/50
-2x 76/50mm AA

Hangar for 1 airplane

The V-78 class of two submarines served the basis for Antaran fleet boats, with the only noticeable differences between subsequent classes being the removal of the 155mm gun in place of the more favourable and lighter 100mm and 127mm gun. The V-78 class carried 20 torpedoes including reloads.

Displacement:
1 289 t light; 1 326 t standard; 1 610 t normal; 1 838 t full load

Dimensions:
-Length 125m
-Beam 9.5m
-Draft 5m
Performance:
-25 knots surfaced
-9.1 knots submerged
-15,000nm @ 10 knots on the surface
-Max depth: on average 160m
-Test depth: 180m
Manning:
-10 Officers
-74 Enlisted
Armament:
-155mm/60 Mk14 with 90 rounds
-Twin 20mm/60 NM

Displacement:
~4,100 tonnes surfaced
~4,600 tonnes submerged.

4 x 6400 hp steam turbines for ~25 knots surfaced, 2 x 2400 hp electric motors for ~9.5 knots submerged. 2 x 500 hp diesel generators for battery charging.
10 x 550mm torpedo tubes, 20 reloads.
4 x 140mm SP guns w/2500 rounds.
2 x 84mm AA guns w/300 rounds.
Test depth 90m.
Range of 25,000 km @ 10 knots surfaced, 130 km @ 4.5 knots submerged.
Upper hull armoured against destroyer-calibre gunfire w/90mm plating.

One specially designed watertight semi-submersible cutter carried in a pocket forward, able to be launched with boarding party already aboard while at periscope depth. One floatplane carried disassembled.

Crew of 109 officers and enlisted.

A follow on from the 1913 Vickers-Kaurna project for a steam powered submarine, (the Artemisiya), these much improved versions kept the high surface speed of the class, but fitted their boilers inside separate pressure hulls, permitting free-flooding of the boiler rooms, as well as keeping the crew safer from dangerous heat-buildups in the tropics. Two flotillas were built in the early 1920's, only to fall victim to the First London Naval Treaty's ban on large submarines.

...heuhen

A little overkill, but I wanted it to be different

C-Class

design based on Norwegian A-class submarine just made larger..., an added some extra equipment. Larger than most, where cost is not so important, using untested ideas early in a try aa fail procedure!

Interior design:

-the biggest section of the pressure hull have 2 full deck and a battery deck, but in rest of the ship except engine room and torpedo room/magazine it's 1 deck and battery deck.

-Torpedo room are one big room that are going over 2 decks, the magazine allone can hold 18 torpedos with space for 8 more if needed where 3 torpedo have to be stored on the torpedo tube deck.
between the torpedo tubes/magazine and the turret there is crew berthing for both enlisted and officers. mess hall are toward aft in the ship
magazine are stored in a protected room in the keel, it's a very tight room and only the smallest of the crew members can work there.

-command deck is placed in the center of the ship, aft of main turret. It consist of a: non-pressurized bridge deck in the sail, a weather deck on top of the sail, and a command deck in the pressurized hull. there is also an lower command deck, it is only used as an emergency deck, where you can control the submarine mechanically.

-Aft submarine consist of engineering: here you can find diesel engines and generators and electric motors, the engine room is an open room that is going over 2 deck. with one of the 3 battery banks.
-Aft and above the engine room, is the 400 mm torpedo room, it's a small room.

-The sail have a bridge deck, and an Hangar, the Hangar are big enough for an larger airplane, but would normally carry two, tiny short range airplane. In peacetime the submarine carry a VIP-boat instead of an airplane.





Class overview
Type: Cruiser Submarine
Planed: 1915-1920
Build: 1921-1923
Commission: 1925-1942
Completed: 6

General characteristics
Displacement:
Surface: around 3800 tons
Submerged: 4700 tons
Length: 115.7 m (379 ft 6 in)
Beam: 9.3 m (30 ft 5 in)
Draft: 6.4/0 m (21 ft)

Propulsion:
Diesel-electric
4 diesel engines tot. 9000 hp
2 electric engines tot. 4000 hp
2 screws

Speed:
Surface: 22 knots (trail speed: 24 knots)
Submerged: 10 knots

Range:
13,500 nm at 12 knots (surfaced)
150 nm at 6 knots (submerged)

Dive depth:
Max depth: 180 m
Test depth: 230 m

Complement:
12 officers
80 Enlisted

Armament:
1x twin modified 155 mm Bofors turret
1x single 4 in Mk V (modified)
12x railing mounted/handheld from 4 to 8 mm machine guns of various types, in addition to 2x sniper rifle
8x bow 21 in (533 mm) torpedo tubes
- in tubes: 8x 21 in (533 mm) torpedos
- magazine: 18x 21 in (533 mm) torpedos (Standard) space for additional 8
4x Aft 16 in (400 mm) torpedo tubes
- in tube: 4x 16 in (400 mm) torpedos
- magazine: 6x 16 in (400 mm) torpedos
With modification, can carry and deploy mines and store mines in hangar, up to 16 mines (8 on aft deck, single row)


2 in deck lifeboat

Build with hangar for 1 large airplane or 2 tiny airplane, used in peacetime to store an large VIP-boat

An alternative version, that I just did fast, by modifying the last drawing:



Data on it shouldn't differ to much from that era of submarines. I can just add in that she have 6x 533 mm forward tubes and 4x 400mm aft tubes and 2x 4 in guns and 1x 3 in gun

Laid down: 1938

Displacement: 3,300 tons surfaced, 4,500 tons submerged

Propulsion: 2x direct drive 6 cylinder diesel engines totaling 3,000-3,500 shp, 2x electric motors totaling 2,400 shp

Speed: 16 kts surfaced, 8 kts submerged

Range: 9,000 nmi at 10 kts surfaced, 100 nmi at 4 kts submerged, 18,000 nmi with fuel in main ballast tanks

Test depth: 150 m

Armament: 1 aircraft (carrying bombs, aerial mines, or one torpedo), 6x 21" torpedo tubes (4 bow, 2 stern, 16 torpedoes in reserves), 1x 152mm wet mount deck gun, 2x 13.2mm MG, 25x naval mines internal tubes, 40 external

Here's a little addition to my entry.

Based on the M-Class the Magnificent and its 3 sisters were built to operate from Singapore out into the Pacific and Indian Oceans where the Royal Navy did not have a large presence.

With a twin 7.5" turret aft and a hangar for one aircraft forward, the hull had to be quite beamy and longer to take the large amount of topweight that had been added to what had been originally a K-Class hull design. The extra length allowed for a bigger diesel installation and battery complement so that it might make 18 knots surfaced and 8 knots submerged. Those speeds gave the boats enough of a leeway to catch most merchantmen and only the faster 'liner' types would have the speed to escape.

Here is my take, from Koko, obviously

During the late 20's as part of their submarine buildup project, Koko no Kaigun came up requesting a design for a large ocean-going cruiser submarine to supplement the small and medium boats being built and designed during the decade. Requirements called for long range, heavy armament and spotting capabilities optimized for SubRon leader duties and prolonged solitary deployments. The resulting design was the largest submarine ever put into paper for Koko no Kaigun up to that point, and would remain so for over a decade.
As planned the boat would have been 109,9m long, 9,7m abeam and with a surfaced draft of 5,9m. All for a displacement of 2.847t surfaced and 4.214 submerged. Poweplant was intended to be two diesel-electric motors capable of generatin 8.600shp surfaced and 3.000 submerged, allowing for a top speed of 18knots above the surface and 8knots below. Fuel bunkers allowed for an endurance of 17.500 nautical miles (32.410km) at 10knots, while on batteries they could travel submerged for 70nautical miles (130km) at 3knots. Some of the ballast tanks could have also been double-used as extra fuel bunkers, extending the range to 21.000 nautical miles (38,892km) if ever needed. Design depth was 140m, with test depth set at 80m. Armament wise, the submarines would have been fitted with two 120mm/45 Type11 guns in single mounts, one for and one aft of the sail, plus a single 13mm/76 Type93 machine gun. A total of eight 533mm torpedo tubes were also planned, six at the bow and two at the stern, with a full complement of 24 warheads carried. Finally, aircraft facilities with a catapult and a small hangar to carry and operate a single Yokosuka E6Y1 floatplane were to occupy most of the quarterdeck. 86 men (8 officers plus 78 enlisted) would have manned the submarine, plus two mechanics, one pilot and one obesrver to man the reconnaissance plane and aircraft facilities, for a grand total of 90.
The design was finally approved in late 1929, with the order placed for at least two boats (with Koko no Kaigun planning to order more if the sea trails would have resulted successful), to be laid down by the end of 1930.
The project was eventually killed by the ratification of the London Naval Treaty, which put the entire Koko no Kaigun submarine buildup program to a complete stop for more than three years (construction of large-sized units wouldn't even resume until five).