Kraken-Class Submarine
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Kraken-Class Submarine | |
|---|---|
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Service Information | |
| Nation | Republic of Gondara |
| Branch | Republic of Gondara Navy |
| Class | Kraken-class |
| Type | Long-range attack submarine |
| Role | Deep-ocean attack, strategic raiding, fleet reconnaissance, maritime interdiction |
| Status | Active |
| Operator | Republic of Gondara Navy
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Construction | |
| Builder | Classified naval construction facilities |
| Commissioned | 1940 |
| Planned | Serial production |
| Completed | 2 |
| Active | 1 |
| Lost | 0
|
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General Characteristics | |
| Surfaced displacement | ~2,050 long tons |
| Submerged displacement | ~2,400 long tons |
| Length | 206 ft |
| Beam | 28.2 ft |
| Draft | ~20 ft 6 in |
| Complement | 55 |
| Patrol endurance | ~90 days
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|
Hull and Diving | |
| Hull construction | High-tensile Gondaran steel |
| Hull form | Submerged-optimized teardrop |
| Operating depth | 100 m+; exact limit classified |
| Test depth | Classified |
| Crush depth | 200 m+; exact limit classified
|
|
Propulsion and Performance | |
| Propulsion | Tri-propulsion diesel-electric / battery-electric / closed-cycle HTP system |
| Diesel plant | 2 × 2,000 bhp diesel-generator sets |
| Electric plant | 2 × 1,250 shp main motors; 2 × ~100 shp creeping motors |
| Special propulsion | 2 × ~8,000 shp HTP closed-cycle turbines |
| Shafts | 2 |
| Surface speed | 10 kn |
| Snorkel speed | 10 kn standard transit |
| Battery speed | 12 kn maximum; 5 kn silent running |
| HTP speed | 24 kn submerged — HTP sprint; acoustically loud |
| Combat range | ~13,300 nmi |
| Maximum range | ~17,000 nmi in maximum-fuel/light-load configuration |
| Battery endurance | ~60 hr at 3 kn; ~24–30 hr at 5 kn; ~1.5–2 hr at 10 kn |
| HTP endurance | ~150 min total HTP; doctrinally 12 × 10-min combat allowances + 3 × 10-min emergency reserve
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Sensors and Fire Control | |
| Passive sonar | Wide-aperture passive hydrophone array |
| Active sonar | Short-range active ranging sonar |
| Fire control | Electromechanical torpedo fire-control computer with gyro-angle solution |
| Periscopes | Attack and observation/navigation periscopes |
| Air-search optic | Wide-angle panoramic pre-surfacing sky-search optic |
| Communications | Low-frequency receiving equipment; retractable radio mast for surfaced/snorkel transmission
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Armament | |
| Torpedo tubes | 8 × 550 mm (6 bow, 2 stern) |
| Weapons carried | 24 torpedoes or mines |
| Mines | Carried in place of torpedoes as required |
| Deck gun | None |
| Anti-aircraft | None |
Kraken-Class Submarine is a long-range attack submarine developed by the Leviathan Project for the Republic of Gondara Navy.
Entering operational service in 1940, the Kraken represented a fundamental departure from conventional submarine design. Rather than treating submergence as a temporary operating condition imposed upon an otherwise surface-oriented vessel, the Kraken was designed from its inception to travel, hunt, attack, maneuver, and evade while submerged.
The class combines an underwater-optimized hull, exceptional diving capability, long-range snorkel transit, quiet battery-electric propulsion, dedicated silent-running motors, and a classified high-test peroxide closed-cycle turbine system capable of driving the submarine to approximately 24 knots underwater.
The HTP system does not make the Kraken silent. At full power it produces substantial machinery, shaft, propeller, and hydrodynamic noise and is assumed to compromise the submarine's acoustic concealment. Its purpose is instead to give the commander the ability to rapidly alter engagement geometry before enemy anti-submarine forces can establish or maintain an accurate attack solution.
Kraken doctrine therefore centers not on continuously outrunning enemy escorts, but on remaining ahead of the position where the enemy expects the submarine to be.
Development
Leviathan Project
The Kraken was developed under the highly classified Leviathan Project, Gondara's permanent national program for advanced undersea warfare.
Leviathan was not established around a single submarine class. It was created to investigate emerging technologies in:
- Submerged propulsion
- Pressure-hull construction
- Hydrodynamics
- Deep-diving systems
- Acoustic detection and concealment
- Submarine weapons
- Crew endurance
- Underwater navigation
- Submerged tactical doctrine
Unlike normal Gondaran procurement programs, Leviathan was permitted to construct expensive experimental systems whose success could not be guaranteed in advance.
This freedom did not remove engineering discipline. Experimental failures were required to produce usable technical knowledge and were incorporated directly into later development.
The principal Leviathan research center operated in the Strait of Talakar, where the deep tectonic rift provided an isolated natural environment for deep-diving, submerged-speed, propulsion, and endurance testing.
Experimental Leviathan
One of the program's earliest major research vessels was the experimental submarine Leviathan.
Leviathan incorporated Gondara's first experimental titanium submarine pressure hull and attempted to use hydrogen-cell technology as a submerged power source.
The hydrogen-cell propulsion system ultimately proved unsuitable for operational submarine use.
The vessel nevertheless demonstrated the extraordinary potential of advanced pressure-hull construction. Leviathan could descend to approximately 300 meters for short periods, but sustained operation at such depths exposed a critical engineering problem: the pressure hull itself was not necessarily the first component to fail.
Valves, seals, penetrations, fittings, piping, and supporting machinery increasingly suffered failures as depth and exposure time increased.
The vessel proved considerably more reliable around 150 meters.
During one test, a diving-system failure stranded Leviathan on the seabed for approximately one week. The submarine was eventually recovered, although with extensive damage.
The incident reinforced a fundamental Leviathan design principle:
- A submarine is only as deep-diving as its weakest pressure-dependent system.
Lessons from Leviathan were later incorporated into the Alpha pressure program and ultimately the production Kraken.
Kraken Alpha
Kraken Alpha was constructed as a dedicated pressure, endurance, diving, and crew-effects test vessel.
Alpha was not shaped like the eventual production Kraken and did not carry its complete tri-propulsion system.
Its research program concentrated on:
- Deep-pressure operation
- Rapid crash diving
- Repeated pressure cycling
- Seal and valve reliability
- Hull penetrations
- Hydraulic and electrical systems
- Prolonged submerged operation
- Crew endurance
- Habitability under extended confinement
Alpha's purpose was to ensure that the entire submarine could continue functioning at depth rather than merely proving that a pressure cylinder could survive.
Kraken Bravo
Kraken Bravo was developed separately as a propulsion and hydrodynamic test vessel.
Bravo was smaller and lighter than the eventual production Kraken and carried minimal accommodations and approximately one week of stores. It was never intended for combat operations.
The vessel existed to answer a much narrower question:
- How fast can a practical submarine move underwater, and what breaks when it does?
Bravo tested:
- High-test peroxide closed-cycle propulsion
- Hydrodynamic hull forms
- High-speed submerged control
- Propulsion transitions
- Shaft loading
- Propeller behavior
- High-speed stability
Approximate trial performance included:
| Propulsion Mode | Approximate Performance |
|---|---|
| Diesel / surface | 15–16 kn |
| Battery-electric | 12–13 kn |
| HTP repeatable trial speed | ~28 kn |
| HTP maximum instrumented trial | ~29–29.5 kn |
Bravo demonstrated that extremely high submerged speed was technically possible, but also exposed the mechanical, acoustic, reliability, and endurance penalties associated with achieving it.
The production Kraken was deliberately derated to approximately 24 knots.
Compartmentalized Development
Alpha and Bravo were deliberately developed as separate programs.
Personnel assigned to Alpha did not possess complete knowledge of Bravo's propulsion work, while Bravo personnel did not possess complete knowledge of Alpha's pressure and endurance research.
Neither experimental vessel represented the final production configuration.
This compartmentalization reduced the number of individuals capable of reconstructing the complete Kraken design and limited the damage that could result from espionage, capture, or accidental disclosure.
Kraken 001
Kraken 001 was the first production Kraken-class submarine.
Unlike Alpha and Bravo, 001 was not a technology demonstrator. It incorporated the validated results of both programs into a complete combat submarine with:
- Long-range fuel capacity
- Crew accommodations
- Torpedo armament
- Sensors
- Communications
- Battery systems
- Diesel generation
- HTP propulsion
- Deep-diving systems
- Operational stores
Kraken 001 conducted its maiden voyage in January 1940.
The submarine then underwent several months of machinery testing, deep-diving certification, propulsion trials, crew work-up, weapons testing, and tactical exercises.
Kraken 001 entered operational wartime service in June 1940.
At the same time, Kraken 002 was transiting to begin its own sea trials, marking the beginning of the serial production run.
Design Philosophy
An Underwater Warship
The Kraken is designed as an underwater warship rather than a surface vessel capable of submerging.
Surface performance was therefore deliberately sacrificed in favor of:
- Low submerged drag
- High underwater speed
- Deep-diving capability
- Long submerged endurance
- Quiet low-speed operation
- Reduced exposed superstructure
- Efficient underwater control
Routine surface transit is discouraged.
Under normal patrol conditions, the Kraken is expected to spend approximately 99 percent of its operational time submerged.
Hull Form
The production Kraken uses a submerged-optimized teardrop hull form.
The streamlined hull reduces underwater drag and permits significantly greater submerged efficiency than conventional submarines designed around favorable surface characteristics.
The submarine measures:
| Characteristic | Specification |
|---|---|
| Surfaced displacement | ~2,050 long tons |
| Submerged displacement | ~2,400 long tons |
| Length | 206 ft |
| Beam | 28.2 ft |
| Draft | ~20 ft 6 in |
| Complement | 55 |
The pressure hull is constructed from high-tensile Gondaran steel.
Titanium construction, despite earlier Leviathan experimentation, remained too expensive and labor-intensive for fleet-scale submarine construction during the early production period.
Diving Capability
The exact diving limits of the Kraken are classified.
Public and general fleet documentation describes the class as capable of sustained operations beyond 100 meters.
Its structural crush depth is known to exceed 200 meters, although the exact figure is restricted.
| Depth Classification | Published Figure |
|---|---|
| Operating depth | 100 m+; exact limit classified |
| Test depth | Classified |
| Crush depth | 200 m+; exact limit classified |
The class is designed around the lessons learned from experimental Leviathan and Kraken Alpha.
Deep-diving capability therefore includes not only the pressure hull but also reinforced:
- Valves
- Seals
- Pressure penetrations
- Electrical connections
- Piping systems
- Hydraulic systems
- Machinery mounts
- Torpedo-tube assemblies
Crash Diving
The Kraken can reach periscope depth from the surface in approximately 40 seconds under emergency conditions.
The absence of a deck gun, reduced surface superstructure, and underwater-oriented hull form all contribute to rapid submergence.
Tri-Propulsion System
Kraken's defining engineering feature is its three-mode propulsion architecture.
Each propulsion system serves a different tactical purpose.
Diesel Generation and Snorkel Transit
The submarine carries:
- 2 × 2,000 bhp diesel-generator sets
The diesel plant primarily provides electrical generation and long-range submerged movement beneath a snorkel.
Standard strategic transit speed is approximately 10 knots.
The Kraken is not intended to conduct routine high-speed surface operations.
Maximum surfaced speed is approximately 10 knots.
Battery-Electric Propulsion
Primary submerged propulsion is provided by:
- 2 × 1,250 shp main electric motors
- 2 shafts
Maximum battery-electric speed is approximately 12 knots.
Battery endurance varies sharply with speed:
| Speed | Approximate Endurance | Approximate Distance |
|---|---|---|
| 3 kn | ~60 hours | ~180 nmi |
| 5 kn | ~24–30 hours | ~120–150 nmi |
| 10 kn | ~1.5–2 hours | ~15–20 nmi |
The battery system has approximately 4,000 kWh nominal capacity.
Silent Running
Dedicated low-power creeping motors provide Kraken's formal silent-running capability.
The submarine carries:
- 2 × ~100 shp creeping motors
Silent-running speed is approximately 5 knots.
At this speed, main propulsion machinery is isolated where practical and the propellers are operated at low rotational speed to reduce:
- Machinery vibration
- Shaft noise
- Propeller noise
- Cavitation
- Hydrodynamic disturbance
Three knots may be used for extremely economical creeping or loitering, but five knots represents the class's designed tactical silent-running speed.
HTP Sprint System
The Kraken carries two high-test peroxide closed-cycle turbines:
- 2 × ~8,000 shp HTP turbines
- ~16,000 shp combined
- 2 shafts
Maximum submerged speed under HTP propulsion is approximately 24 knots.
The twin-shaft arrangement divides the enormous torque generated by the HTP plant between two propulsion lines.
This reduces individual shaft, gearbox, coupling, and propeller loading compared with transmitting the complete HTP output through a single shaft.
HTP power is brought online progressively. Turbines must spool and shaft load must rise through a controlled engagement sequence rather than instantaneously applying maximum torque.
The submarine therefore does not transition instantly from silent running to 24 knots.
Acoustic Penalty
HTP propulsion is acoustically loud.
The system produces substantial:
- Turbine noise
- Reduction-gear noise
- Shaft vibration
- Propeller noise
- Hydrodynamic flow noise
- Cavitation risk at high speed
Use of the HTP system is assumed to compromise Kraken's acoustic concealment within tactical listening range.
The submarine's own passive acoustic awareness is also degraded while running at high speed.
HTP therefore represents a deliberate exchange:
- Stealth is sacrificed for temporary mobility.
The system is not intended to provide high-speed silent running.
HTP Endurance
Kraken carries approximately 150 minutes of total HTP sprint endurance.
For patrol planning this is divided into:
- 12 × 10-minute combat allowances
- 3 × 10-minute emergency allowances
These are planning units only.
They do not represent physical charges, separate tanks, or mandatory ten-minute burns.
A commanding officer may use:
- 90 seconds
- 4 minutes
- 7 minutes
- 20 minutes
- 40 minutes
- or any other tactically required duration
The unused portion remains available.
At 24 knots, a ten-minute HTP run covers approximately:
4 nautical miles / 7.4 km
The normal planning assumption provides enough HTP capacity to support a disengagement allowance for each theoretical two-torpedo attack while retaining approximately thirty minutes for emergency use.
Range and Endurance
The Kraken has approximately 90 days of patrol endurance.
Normal combat-patrol range is approximately:
13,300 nautical miles
at the class's standard 10-knot strategic snorkel-transit profile.
Normal fuel capacity is approximately:
230 long tons
An extreme maximum-fuel configuration can increase fuel load to approximately:
285 long tons
and produce a theoretical range approaching:
17,000 nautical miles
This configuration significantly reduces useful combat load and operating margin and is intended for exceptional ferry or strategic-transfer missions rather than normal combat patrols.
Armament
Torpedo Battery
The Kraken is armed with eight 550 mm torpedo tubes:
- 6 × bow tubes
- 2 × stern tubes
Total weapons carried:
24 torpedoes or mines, including weapons already loaded in the tubes
The six forward tubes form the primary attack battery.
The stern tubes serve both offensive and defensive purposes.
Stern Torpedo Doctrine
The stern battery is particularly important to Kraken's disengagement doctrine.
A pursuing escort may be capable of matching Kraken's HTP sprint speed. A vessel already behind the submarine, however, cannot easily close the existing distance if both vessels are traveling at approximately the same speed.
A torpedo fired from Kraken's stern tubes further complicates pursuit.
An escort forced to:
- Turn
- Change speed
- Alter heading
- Evade a torpedo
- Break its attack run
loses both time and pursuit geometry.
Kraken can continue opening or maintaining separation while the escort deals with the incoming weapon.
The stern battery therefore allows the submarine to weaponize pursuit itself.
Harpoon IV Torpedo
The Harpoon IV Torpedo provides Kraken with a standoff attack capability of approximately 13.5 miles.
This permits the submarine to attack major naval targets without necessarily penetrating directly into an inner anchorage.
The combination of long-range torpedoes and high-speed submerged escape is central to Kraken strike doctrine.
Mine Warfare
Naval mines may replace part of the normal torpedo load when required.
Typical missions include:
- Harbor approaches
- Shipping lanes
- Fleet-anchorages approaches
- Chokepoints
- Strategic maritime interdiction
Deck and Anti-Aircraft Weapons
Kraken carries no deck gun.
Kraken carries no dedicated anti-aircraft armament.
This is deliberate.
The submarine is not intended to surface and fight.
If the crew is forced into a surface engagement, the tactical situation is already considered severely compromised.
Sensors and Fire Control
Passive Acoustic Detection
The Kraken uses a wide-aperture passive hydrophone array as its principal underwater detection system.
Passive listening is preferred because it permits the submarine to locate, classify, and track vessels without transmitting a signal that may reveal its own position.
The system is particularly important during:
- Silent approach
- Convoy stalking
- Harbor penetration
- Target classification
- Post-attack evasion
Active Ranging
A short-range active acoustic ranging system is available when precise range information is operationally necessary.
Active transmission is used sparingly because it may reveal the submarine's approximate position.
Torpedo Fire Control
An electromechanical torpedo fire-control computer calculates attack solutions using:
- Target bearing
- Estimated target speed
- Target course
- Own-ship movement
- Torpedo characteristics
- Gyro angle
This permits attacks without requiring the submarine to physically align every torpedo tube directly with the predicted target track.
Periscopes
The Kraken carries:
- Attack periscope
- Observation/navigation periscope
Periscope exposure is minimized whenever possible.
Pre-Surfacing Air Search
Because maritime patrol aircraft represent one of the Kraken's greatest vulnerabilities, the submarine carries a dedicated wide-angle panoramic optical system for checking the surrounding sky before surfacing or exposing the snorkel more extensively.
The device uses a broad fisheye-style optical view intended for rapid aerial warning rather than detailed identification.
Its original project designation remains restricted.
Acoustic Detection and Tracking
Kraken is not acoustically invisible.
Its effectiveness depends heavily upon the distinction between:
detection
and
localization
and
successful weapons employment.
Enemy hydrophones may detect a Kraken operating under HTP power from several miles away under favorable conditions.
A typical tactical listening environment may permit detection of a loud HTP-running Kraken at approximately 5–8 nautical miles, although actual performance varies considerably with:
- Water temperature
- Depth
- Acoustic layers
- Sea state
- Receiving equipment
- Background noise
- Listening-vessel speed
- Machinery noise
- Relative bearing
Passive detection normally provides a bearing more readily than an exact range.
This distinction is central to Kraken tactics.
Operational Doctrine
Outrunning the Solution
Kraken doctrine does not assume that the submarine can permanently outrun every anti-submarine vessel.
Instead, the HTP system is used to outrun the enemy's localization and attack solution.
A conventional submarine detected at one location may be expected to occupy a relatively limited search area several minutes later.
A Kraken traveling at 24 knots can rapidly move beyond that predicted area.
At maximum HTP speed, Kraken travels approximately:
| Time | Distance |
|---|---|
| 1 minute | ~0.4 nmi / 0.74 km |
| 2 minutes | ~0.8 nmi / 1.48 km |
| 5 minutes | ~2 nmi / 3.7 km |
| 10 minutes | ~4 nmi / 7.4 km |
| 20 minutes | ~8 nmi / 14.8 km |
| 30 minutes | ~12 nmi / 22.2 km |
Depth charges detonating hundreds of meters behind the submarine are irrelevant regardless of how accurately they attack the position where Kraken was expected to be.
The objective is therefore not always to leave acoustic detection range.
The objective is to remain ahead of the enemy's ability to predict, localize, maneuver, and attack.
Fire, Turn, Run
A standard planned attack profile is:
- Approach quietly
- Establish firing solution
- Launch torpedoes
- Turn toward escape geometry
- Engage HTP propulsion if required
- Rapidly displace from the attack area
- Break or distort the enemy's localization solution
- Shut down HTP
- Return to silent-running speed
HTP use is not mandatory after every attack.
A clean engagement may allow Kraken to simply withdraw quietly.
The commanding officer determines whether speed or silence presents the greater tactical advantage.
Convoy Maneuver
HTP may be used offensively before an attack.
A Kraken commander may temporarily sprint around a convoy or battle group in order to move ahead of its projected course.
The submarine can then shut down the HTP system, return to silent running, and allow the target formation to approach the new firing position.
This allows the peroxide reserve to function as a maneuver resource rather than merely an escape system.
Secure-Port and Anchorage Strike
Kraken performed particularly well in secure-port penetration and anchorage-strike exercises.
The submarine does not necessarily need to penetrate deeply into an enemy harbor.
The long range of the Harpoon IV permits Kraken to remain as much as approximately 13.5 miles from the intended target while still conducting an attack.
A preferred strike profile may therefore involve:
- Silent penetration of outer defensive waters
- Avoidance of patrol craft and acoustic screens
- Establishment of a standoff firing position
- Launch of a heavy torpedo salvo against anchored capital ships or carriers
- Immediate turn toward open water
- Sustained HTP escape before harbor defenses can form an effective containment envelope
The central advantage is reaction time.
Enemy harbor defenses must:
- Detect the attack
- Determine that a submarine is responsible
- Localize the submarine
- Alert patrol vessels
- Sortie escorts
- Establish search sectors
- Launch aircraft
- Close defensive barriers where possible
- Predict the submarine's escape route
Kraken may already be several miles farther seaward before that process is complete.
The submarine therefore does not necessarily need to outrun the entire defensive screen.
It needs to remain ahead of the closing mouth of the response envelope.
Maximum-Effort Escape
In an exceptional high-value strike, the captain may expend a very large portion of the HTP reserve in a single escape.
If Kraken has penetrated a defended anchorage, fired a major portion of its torpedo load against a carrier or battleship concentration, and faces converging harbor defenses, conserving peroxide for later attacks becomes secondary to survival.
A sustained thirty-minute HTP run covers approximately:
12 nautical miles / 22 km
A sixty-minute run covers approximately:
24 nautical miles / 44 km
Such use is expensive and acoustically obvious, but may allow the submarine to escape before defenders can close the available exit routes.
HTP and Acoustic Masking
The sudden acoustic output produced when the HTP plant engages can temporarily complicate enemy acoustic interpretation.
Following a torpedo launch, enemy hydrophones may simultaneously receive:
- Torpedo propulsion noise
- Kraken's propeller noise
- HTP turbine noise
- Reduction-gear noise
- Increased shaft noise
- Hydrodynamic flow noise
When the submarine and outgoing weapons initially occupy similar bearings, the HTP signature may temporarily mask or complicate identification of the torpedoes.
This effect is not reliable.
As the torpedoes move toward the target and Kraken moves away, the acoustic sources separate and become easier to distinguish.
HTP operation therefore provides no guaranteed torpedo concealment.
It may, however, delay enemy understanding of the complete acoustic picture during the first moments of an attack.
Early-War Intelligence Advantage
The Kraken's early combat advantage is increased by enemy expectations regarding contemporary submarine performance.
A defending force may correctly detect an underwater contact while still incorrectly predicting where that contact will move.
If an enemy plotting team assumes a submerged speed near 8–10 knots while Kraken is actually traveling at 24 knots, the positional error expands rapidly.
The submarine may therefore remain acoustically detectable while still causing attacks and search patterns to converge on obsolete locations.
This advantage is expected to decline as foreign intelligence services accumulate combat reports and begin recognizing:
- Kraken's unusually high submerged speed
- Characteristic HTP acoustic signature
- Two stern torpedo tubes
- Long-range torpedo employment
- Sudden transition from loud sprint to quiet battery operation
- Exceptional underwater endurance
Kraken's physical capabilities do not decrease as the enemy learns.
Its initial advantage of surprise does.
Production
Early Kraken construction is extremely expensive and labor intensive.
The first production submarines require extensive work by master craftsmen in areas including:
- Pressure-hull fabrication
- Precision machining
- HTP systems
- Turbine construction
- Shaft alignment
- High-pressure fittings
- Valves and seals
- Electrical penetrations
Approximately 20 secure submarine construction bays are committed to the production program.
A Kraken occupies a construction bay for approximately 10 months during the early production period.
Once all bays are operating as a staggered pipeline, the system is intended to support an average launch rate approaching:
2 hulls per month
Launch does not represent immediate combat availability.
After launch, each submarine must undergo:
- Fitting out
- Harbor trials
- Sea trials
- Pressure certification
- Propulsion testing
- Weapons testing
- Crew training
- Tactical work-up
Production gradually transitions from individually hand-built submarines toward standardized production using:
- Jigs
- Standardized hull sections
- Repeatable pipe runs
- Common fittings
- Interchangeable components
- Dedicated tooling
- Standardized machinery installation
Critical components continue to receive master-level fitting and inspection.
Early production cost is approximately:
$4.8 million per submarine in 1940
Production Status — June 1940
| Vessel | Status | Notes |
|---|---|---|
| Kraken 001 | Operational | Maiden voyage January 1940; completed trials and work-up; entered wartime operational service June 1940 |
| Kraken 002 | Sea trials | Completed initial construction and transiting to begin sea trials in June 1940 |
| 003 onward | Under construction | Serial production pipeline underway across secure construction facilities |
June 1940 marks the beginning of the production run rather than the completion of a large operational fleet.
Development Vessels
| Vessel | Primary Purpose | Combat Vessel | Notes |
|---|---|---|---|
| Leviathan | Experimental pressure-hull and hydrogen-cell research | No | Experimental titanium submarine; stranded on seabed for approximately one week during testing |
| Kraken Alpha | Pressure, depth, endurance, and crash-dive research | No | Separate experimental configuration; no complete tri-propulsion system |
| Kraken Bravo | HTP propulsion and high-speed hydrodynamics | No | Lightweight test boat; approximately one week of stores; reached nearly 30 kn during maximum trials |
| Kraken 001 | First integrated production submarine | Yes | Maiden voyage January 1940; operational June 1940 |
| Kraken 002 | Second production submarine | Yes | Entering sea trials June 1940 |
Specifications
| Characteristic | Specification |
|---|---|
| Type | Long-range attack submarine |
| Surfaced displacement | ~2,050 long tons |
| Submerged displacement | ~2,400 long tons |
| Length | 206 ft |
| Beam | 28.2 ft |
| Draft | ~20 ft 6 in |
| Complement | 55 |
| Patrol endurance | ~90 days |
| Operating depth | 100 m+; exact limit classified |
| Test depth | Classified |
| Crush depth | 200 m+; exact limit classified |
| Diesel plant | 2 × 2,000 bhp diesel-generator sets |
| Main electric motors | 2 × 1,250 shp |
| Silent-running motors | 2 × ~100 shp |
| HTP plant | 2 × ~8,000 shp closed-cycle turbines |
| Shafts | 2 |
| Surface speed | 10 kn |
| Snorkel transit | 10 kn |
| Silent-running speed | 5 kn |
| Battery maximum | 12 kn |
| HTP maximum | 24 kn submerged |
| Combat range | ~13,300 nmi |
| Extreme range | ~17,000 nmi in maximum-fuel/light-load configuration |
| HTP endurance | ~150 minutes total |
| HTP planning allocation | 12 × 10-minute combat allowances + 3 × 10-minute emergency allowances |
| Torpedo tubes | 8 × 550 mm — 6 bow / 2 stern |
| Weapons carried | 24 torpedoes or mines |
| Deck gun | None |
| Anti-aircraft armament | None |