Hubbry Logo
SeehundSeehundMain
Open search
Seehund
Community hub
Seehund
logo
8 pages, 0 posts
0 subscribers
Be the first to start a discussion here.
Be the first to start a discussion here.
Seehund
Seehund
Seehund
View on Wikipedia
from Wikipedia
A Seehund midget submarine, on display at the Deutsches Marinemuseum, Wilhelmshaven, Lower Saxony, Germany
Class overview
NameSeehund
BuildersGermaniawerft, Kiel
Operators
Built1944–1945
In commission1944–1953
Planned1,000
Completed285
Active138
Lost35
General characteristics
TypeMidget submarine
Displacement17 long tons (17 t) (submerged)
Length12 m (39 ft 4 in)
Beam1.5 m (4 ft 11 in)
Propulsion
Speed
  • 7 knots (13 km/h; 8.1 mph) (surfaced)
  • 6 knots (11 km/h; 6.9 mph) (submerged)
Range
  • 270 nmi (500 km; 310 mi) at 7 knots (13 km/h; 8.1 mph) (surfaced)
  • 63 nmi (117 km; 72 mi) at 4 knots (7.4 km/h; 4.6 mph) (submerged)
Complement2
Armament2 × G7e(TIIIc) torpedoes

Seehund (German: "seal"), also known as Type XXVII, was a midget submarine built by Nazi Germany during World War II. Designed in 1944 and operated by two-man crews, it was used by the Kriegsmarine (German Navy) during the closing months of the war, sinking nine merchant vessels and damaging an additional three, while losing 35 boats, mostly attributed to bad weather. The French Navy used four captured boats after the war until 1953.

History

[edit]

The origin of the Seehund began with the salvage of the two British X class submarines HMS X6 and X7 which had been lost by the Royal Navy during Operation Source, an attempt to sink the German battleship Tirpitz. Hauptamt Kriegschiffbau subsequently produced a design for a two-man submarine based on inspection of the British boats, designated Type XXVIIA and named Hecht ("Pike").

XXVIIA (Hecht)

[edit]
Main article: Hecht (submarine)

Like the British X class boats, the Type XXVIIA was designed to carry explosive charges to be laid beneath enemy ships, but it was markedly smaller and had substantial differences from the X class. It dispensed with a dual diesel/electric propulsion system, relying instead solely on electrical power in the form of a 12-brake-horsepower (8.9 kW) AEG torpedo motor, on the basis that since it would operate submerged there was no need for a diesel engine. However, this resulted in a very low endurance of 69 nautical miles (128 km; 79 mi) at 4 knots (7.4 km/h; 4.6 mph).

Since the boat would need to be able to pass through anti-submarine nets and similar obstacles, it was designed without hydroplanes or fins, her trim being controlled with adjustable weights within the pressure hull. In practice this proved totally ineffective since the weights could not be moved quickly enough, and hydroplanes and fins were subsequently fitted. Submerged control was still poor, since Hecht was not fitted with ballast tanks.

Interior of a salvaged Seehund submarine, Bundeswehr Military History Museum, Dresden
Salvaged Seehund submarine, Bundeswehr Military History Museum, Dresden

Even though Hecht had been designed to transport an explosive charge, Karl Dönitz insisted that a torpedo be carried so that attacks could be carried out on vessels in coastal waters.

Externally, Hecht resembled the British Welman submarine. The detachable explosive charge was fitted to the nose of the submarine, while the forward section held the battery and a gyrocompass, the first to be fitted to a German midget submarine and considered essential for navigation if the craft was to operate submerged. Behind this was the control compartment with seats for the two-man crew arranged one behind the other on the centerline with the engineer in front and the commander behind him. The commander was provided with a periscope and a clear acrylic dome for navigational purposes.

On 18 January 1944, Dönitz discussed the new design with Adolf Hitler who expressed his approval, and on 9 March contracts were placed with Germaniawerft of Kiel for construction of a prototype, followed by a further contract for 52 submarines on 28 March.

The 53 Hechts were constructed between May and August 1944: in the event, none saw active service but were instead used to train Seehund crews.

Type XXVIIB

[edit]

As the orders were being placed, Hecht variants were under construction. The first was the Type XXVIIB, which had a greater range, could carry two G7e(TIIIc) torpedoes, and had diesel/electric propulsion. The design was completed at the end of June 1944 and resembled Hecht but had a better boat-shaped external casing for improved seakeeping while surfaced, and saddle tanks. Additional room had been made inside the pressure hull by moving the batteries to the keel, while the two torpedoes were mounted externally in recesses in the lower hull. A 22-brake-horsepower (16 kW) diesel engine was fitted for surface use and was estimated to give a surfaced speed of 5.5 knots (10.2 km/h; 6.3 mph), with a 25-brake-horsepower (19 kW) electric motor providing a submerged speed of 6.9 knots (12.8 km/h; 7.9 mph).

The final variant of the Type XXVII was the Type XXVIIB5, better known as the Seehund ("Seal") or Type 27. Seehund had a small sail midships with the air-intake mast, magnetic compass, periscope, and a clear dome which could survive depths of 45 meters (148 ft). The submarine's fixed 3-meter (9.8 ft) periscope incorporated lenses which let the commander check the sky above for aircraft before surfacing.[1]

Production

[edit]
Seehund 075 at the United States Naval Shipbuilding Museum

The first contract for Seehund construction was placed on 30 July 1944, before the design was completed. A total of 1,000 boats were ordered, of which Germaniawerft and Schichau-Werke were to build 25 and 45 boats per month respectively. Other shipyards that were intended to participate in Seehund production were Cantieri Riuniti dell'Adriatico at Monfalcone, Italy, and Klöckner-Humboldt-Deutz at Ulm. However, Dönitz would not consent to the production of the Type XXIII submarine being held up for Seehund construction, while shortages of raw material, labor and transport problems, and conflicting priorities in Germany's economy all combined to reduce Seehund production. In the end Seehund production was undertaken by Germaniawerft at Kiel in the Konrad bunker which was no longer needed for production of Type XXI or Type XXIII submarines. A total of 285 Seehunds were constructed and allocated numbers in the range U-5001 to U-6442.[2]

Operational service

[edit]
Captured Seehund submarines, 1945

The first Seehund operation took place on 31 December 1944, when 18 craft set out from IJmuiden in the Netherlands. However, this was a disaster – the submarines encountered a storm and only two returned. The first sinking by a Seehund did not occur until February 1945, when a freighter was sunk off Great Yarmouth.[3]

Seehunds operated mainly around the German coast and in the English Channel, and could attack on the surface in turbulent weather, but had to be almost stationary for submerged attacks. From January to April 1945 Seehunds performed 142 sorties, and accounted for about 93,000 gross tons of shipping (British sources estimate 120,000 tons).[4] Administratively, the Seehunds were under the command of Lehrkommandos, which were part of the German Navy's special operations branch. Within each Lehrkommando were subordinate K-Flotilla; K-Flottille 311 was specifically designated to oversee deployment of the Hecht miniature submarine while the Seehund submarines were dispersed between K-Flottille 312, 313, and 314.[5]

From the Allied point of view, the Seehund's small size made it almost impossible for Asdic to get a return from her hull, while her very quiet slow-speed running made her almost immune to detection by hydrophone. As Admiral Sir Charles Little, Commander-in-Chief, Portsmouth, put it, "Fortunately for us these damn things arrived too late in the war to do any damage".[citation needed]

The last Seehund sorties took place on 28 April and 2 May 1945, when two special missions were performed to resupply the besieged German garrison at Dunkirk with rations. The boats carried special food containers (nicknamed "butter torpedoes") instead of torpedoes, and on the return voyage used the containers to carry mail from the Dunkirk garrison.[6]

The French navy received four units as war reparations, and commissioned them as S 621, S 622, S 623 and S624. They were used until August 1953.

Survivors

[edit]
U-S622, at the Musée national de la Marine, Brest, France (2004)
Cutaway of Seehund, at the Bundeswehr Museum of German Defense Technology, Koblenz, Germany

One of the boats used by the French navy post-war, U-5622, is preserved and on display at the Musée national de la Marine in Brest, France.

U-5075 is on display at the United States Naval Shipbuilding Museum, part of the Massachusetts Military Research Center, in Quincy, Massachusetts.[7] Occasional amateur radio events are conducted by this museum ship, using the callsign WW2MAN.

In Germany, Seehunds are displayed at several museums, the Technik Museum Speyer, the Deutsches Museum, Munich, the Marinemuseum Wilhelmshaven and the German Maritime Museum (Deutsches Schiffahrtsmuseum), Bremerhaven, and Curioseum Willingen (which has been test operated by the owners in a local lake). A cutaway of a Seehund is in the exhibition of the Bundeswehr Museum of German Defense Technology located in Koblenz.

In April 2002 the wreck of U-5095 was recovered by the Royal Dutch Navy and a civilian salvage team lying buried beneath a beach at Egmond aan Zee in the Netherlands, after having been run aground there by its crew in February 1945, and the remains are now on display at the IJmuiden bunker museum.[8] Its two onboard torpedoes were found to be still active and their warheads were separated from their delivery systems and control-detonated at sea.[9]

References

[edit]

Further reading

[edit]
[edit]
Revisions and contributorsEdit on WikipediaRead on Wikipedia

Seehund

View on Grokipedia
from Grokipedia
The Seehund (German for "seal"), designated as Type XXVII B, was a compact developed and deployed by Nazi Germany's during the final months of . Designed in under the supervision of the German Naval Construction Board, it measured approximately 38.9 feet in length with a beam of 5.6 feet, displaced 17 tons when submerged, and was crewed by just two personnel: a and an . Armed with two 21-inch G7e torpedoes and powered by a combination of diesel and electric motors, the Seehund achieved a top speed of 7.7 knots surfaced and had a range of 162 nautical miles (300 km) at 7 knots on the surface or 63 nautical miles at 3 knots submerged, with a maximum safe diving depth of 50 meters (164 feet). Although over 1,000 units were initially planned, production constraints limited output to 285 submarines, of which 138 were commissioned between late 1944 and early 1945, with numbers peaking at 70 in December 1944. The Seehund represented an evolution from earlier, less successful German midget submarines like the Molch, Biber, and Hecht, incorporating improvements such as better stability and torpedo armament while remaining lightweight enough to evade depth charges effectively. It could operate on the surface in weather conditions up to Beaufort scale 4 but required near-stationary positioning for accurate torpedo launches. Operationally, the Seehund entered service in December 1944 and conducted 142 sorties between January and April 1945, primarily targeting Allied shipping in the and to disrupt supply lines. These missions, which could last up to 10 days, proved moderately successful: the submarines sank 8 enemy vessels totaling 17,301 gross register tons and damaged 3 others for 18,384 tons, marking the Seehund as the most effective type of German during the . However, the type suffered significant setbacks, with 35 boats lost—mostly to mechanical failures, accidents, or from exhaust leaks—highlighting inherent design vulnerabilities despite its tactical promise. By the 's end in May 1945, further developments like the proposed Type XXVII K with a closed-circuit were abandoned, leaving the Seehund as a poignant example of late-war desperation in German naval innovation.

Development

Origins and early prototypes

The conceptual origins of the Seehund midget submarine program stemmed from the German recovery and examination of two British X-class submarines, HMS X6 and HMS X7, scuttled during —a midget submarine raid against the battleship Tirpitz in Kaafjord, , on 22 September 1943. The salvaged these craft, which had penetrated defended waters to deliver explosive charges, inspiring the development of compact, stealthy submarines suited for coastal attacks on Allied shipping. This analysis highlighted the potential of small, low-noise vessels to evade detection by and hydrophones, prompting the Germans to pursue similar designs amid mounting pressure on their naval forces in 1944. In early 1944, the Kriegsmarine's Hauptamt Kriegschiffbau began initial design efforts for a two-man , drawing directly from the X-craft's principles of mine-laying against anchored targets. The resulting Type XXVIIA, codenamed , was ordered on 28 as a proof-of-concept vehicle to test handling, crew coordination, and basic operations in shallow waters. Construction commenced in May 1944 at Germaniawerft in , with 53 units completed by August 1944; these were allocated solely for training and saw no combat deployment. The Hecht prototypes emphasized simplicity and stealth, featuring all-electric via a single 12 bhp AEG motor that provided a submerged range of 69 nautical miles at 4 knots. Lacking hydroplanes for depth control, they relied on adjustments and were armed with a single explosive charge or for attachment to enemy hulls, mirroring the X-craft's offensive tactic rather than torpedo delivery. These vessels validated the feasibility of two-man crews for extended submerged patrols, with all 53 units expended in training exercises by late 1944 to prepare operators for subsequent variants. The Hecht's limitations in endurance and maneuverability informed refinements leading to the Type XXVIIB.

Design evolution to Type XXVIIB

The Hecht prototype, developed as Type XXVIIA in early , served as the foundational design for subsequent midget submarines, featuring electric-only with a 12 horsepower AEG torpedo motor and relying on adjustable weights for submerged navigation rather than dedicated hydroplanes. This initial configuration limited its operational viability, prompting iterative refinements under the direction of designers such as Dr. Fischer and Engineer Grim from the German Naval Construction Board to address stability and control issues observed during testing. A pivotal evolution occurred with the transition to diesel-electric propulsion in the Type XXVIIB, completed by late June 1944, which incorporated a 60 horsepower diesel engine for surfaced transit and a 25 horsepower AEG electric motor for submerged operations, significantly extending range compared to the Hecht's battery-dependent system. Armament shifted from explosive charges or limpet mines to two externally mounted G7e torpedoes, enabling offensive capabilities against larger vessels rather than solely sabotage roles, while the addition of forward and aft hydroplanes improved submerged maneuverability and stability, resolving the Hecht's reliance on rudimentary ballast adjustments. These changes were informed by hydrodynamic research at the Hamburg Ship Model Basin (HSVA) in June 1944 and towing tests in July, which refined the hull form for better underwater performance. The final Type XXVIIB variant, designated Seehund and often referred to as Type XXVIIB5, emerged in mid-1944 as the operational blueprint, achieving a surfaced range of 300 nautical miles at 7 knots and a submerged range of 63 nautical miles at 3 knots, with maximum speeds of 7.7 knots surfaced and 3 knots submerged, powered by eight 7 MAL 210 battery troughs. This iteration featured a reduced height for a lower surface profile, a fixed 3-meter for , and enhanced box s to mitigate flutter issues identified in earlier profile rudder designs, culminating in a safe diving depth of 30 meters (test depth up to 50 meters). Crew accommodations in the Type XXVIIB emphasized the two-man configuration—a and an —positioned in a cramped midsection with simplified, dual-purpose controls to facilitate rapid training for minimally experienced personnel on short-duration missions. included oxygen bottles and carbon dioxide scrubbers for extended submersion, alongside escape apparatus such as breathing sets to improve survivability in emergencies. Sea trials for the Type XXVIIB prototypes, contracted to Howaldtswerke on July 30, 1944, commenced in and addressed lingering stability concerns from the Hecht by validating the new hydroplane and integrations, leading to the design's approval for operational use by late 1944 after an endurance test covering over 300 nautical miles.

Design

General specifications

The Type XXVIIB Seehund , the final production variant of Germany's late-war coastal assault craft, featured compact dimensions optimized for stealthy inshore operations. Evolving from earlier prototypes like the Hecht, it achieved a streamlined emphasizing minimal visibility and rapid deployment. Key physical characteristics included a surfaced displacement of approximately 12 long tons (12.2 metric tons) and a submerged displacement of 17 long tons (17.3 metric tons), reflecting its lightweight construction for transport by larger vessels or trucks. The overall length measured 12 meters (39 feet), with a beam of 1.7 meters (5 feet 7 inches), a pressure hull of 1.28 meters (4 feet 2 inches), and a draft of 1.45 meters (4 feet 9 inches), allowing in shallow coastal waters while maintaining hydrodynamic efficiency.
SpecificationMetricImperial
Displacement (surfaced)12.2 t12 long tons
Displacement (submerged)17.3 t17 long tons
12 m39 ft
Beam1.7 m5 ft 7 in
Pressure hull diameter1.28 m4 ft 2 in
Draft1.45 m4 ft 9 in
The hull consisted of riveted plates forming a single-hull configuration with low freeboard, which reduced the vessel's profile against and visual detection. In the final variant, the pressure hull had a safe diving depth of 30 meters, with a maximum test depth of up to 70 meters recorded in some instances, balancing structural integrity with the need for economical wartime production. Internally, the layout prioritized functionality in confined space, with the seamlessly integrated into the hull to further minimize silhouette. Compartments were allocated for high-capacity batteries along the , fuel tanks amidships, and basic bunks for the two-man , ensuring essential systems remained accessible during short missions. Endurance was limited by battery capacity to 6-8 hours submerged, with overall missions potentially lasting up to several days when surfacing for recharging and air renewal, though constrained by fatigue in the cramped environment, rendering the Seehund ideally suited for hit-and-run attacks rather than prolonged patrols.

Propulsion and performance

The Seehund midget submarine employed a diesel-electric propulsion system consisting of a single six-cylinder diesel engine rated at 60 horsepower for surfaced operations and an AEG electric motor providing 25 horsepower for submerged running, both driving a single propeller shaft. This setup represented an improvement over earlier prototypes like the Hecht, which had shorter operational ranges due to less efficient power plants. Maximum speeds reached approximately 7.7 knots when surfaced and 6 knots when submerged, though cruising speeds were more typically 5.5 knots surfaced and 4 knots submerged to conserve fuel and battery power. The operational range extended to 270 nautical miles at 7 knots on the surface with standard fuel capacity of about 0.5 tons of diesel, while submerged endurance was limited to 63 nautical miles at 3 knots, relying on battery charge. Some variants incorporated external auxiliary fuel tanks to extend surface range up to 500 nautical miles, though this increased vulnerability to detection. Maneuverability was adequate for its size, with a reported turning radius of around 50 meters at low speeds, enabling tight evasions in confined waters. However, submerged operations were constrained by battery limitations, typically allowing 6-8 hours of evasion at moderate speeds before recharging was necessary via surfaced diesel running. The diesel engine's high noise signature posed a detection risk during transit, but the silent electric mode proved effective for short-range ambushes and stealthy approaches to targets. These trade-offs prioritized compactness and low observability over extended endurance, making the Seehund suitable for coastal raiding but limiting its strategic reach.

Armament and equipment

The Seehund midget submarine's primary armament consisted of two externally mounted G7e electric torpedoes, each with a 533 mm (21-inch) diameter, carried in fixed underslung tubes along the hull. These torpedoes were launched without reload capability at sea, requiring the submarine to position itself directly toward the target for firing. The G7e variant featured an electric propulsion system for stealthy submerged operation and carried a 280 kg explosive , with a maximum range of 5,000 meters at 30 knots. In certain configurations, the Seehund could forgo torpedoes for alternative loads, such as additional fuel storage in external panniers, extending its operational range to 300 nautical miles surfaced at 7 knots or 63 nautical miles submerged at 3 knots for resupply or roles. Due to its compact design, the lacked or advanced systems, relying instead on basic tools including a magnetic and an sounder for depth measurement. A fixed 3-meter provided the primary means of surface observation and targeting. Additional equipment included a signal pistol for emergency surfacing alerts and demolition charges intended for scuttling the vessel if capture was imminent, as demonstrated in wartime incidents where crews initiated self-destruction to prevent salvage. A basic allowed limited passive detection of nearby vessels, though its effectiveness was constrained by the Seehund's small size and power limitations. These features underscored the submarine's emphasis on simplicity and stealth over sophisticated electronics.

Production

Manufacturing sites and process

The primary manufacturing sites for the Seehund midget submarines were the Germaniawerft shipyard in , which acted as the main production facility utilizing the Konrad bunker originally intended for larger types, and the Schichau-Werke in Elbing, which contributed significantly to series construction. Additional planned sites, such as Klöckner-Humboldt-Deutz in and CRDA-Monfalcone in , were allocated for expansion but saw limited or no utilization due to wartime disruptions. The assembly process adopted modular construction methods inspired by mass-production techniques from the automotive and aviation industries, involving the pre-fabrication of hull sections that could be transported by rail, road, or waterway before final integration at the shipyards. These sections were welded or riveted together to form the pressure hull, with interior components like batteries and engines installed only in the later stages to streamline workflow and minimize handling damage. This approach allowed for pressure hull fabrication in approximately 14-20 days, followed by 30 days each for interior assembly and final completion. Production drew on skilled naval yard workers reassigned from other U-boat programs, with efforts to leverage underutilized industrial capacity in safer inland areas to mitigate bombing risks. The timeline began with a ramp-up in September 1944 following prototype trials of the related Hecht design, assigning hull numbers sequentially from U-5001 to U-6442 as boats progressed through the yards. Quality control measures were rudimentary under wartime conditions, limited primarily to harbor-based static and basic dynamic tests before to the , though resource shortages prompted design simplifications and occasional production shortcuts that affected overall reliability. Components, including engines and electrical systems, were sourced from established suppliers like MWM for diesels, enabling rapid integration but constrained by broader material scarcities in non-ferrous metals and skilled labor.

Output quantities and wartime challenges

In mid-1944, the German naval command planned for the production of 1,000 Seehund submarines to equip multiple flotillas of midget submarines for coastal defense and offensive operations. However, only 285 units were completed between September 1944 and May 1945, with the majority of remaining orders canceled as the war ended. Production began slowly, with just 3 boats finished in September 1944, before accelerating to a peak of 70 in December 1944, with subsequent outputs of 35 in January, 27 in February, 46 in March, and declining sharply to 8 in April 1945, leaving many hulls incomplete at Germany's surrender. Several factors severely constrained Seehund output during the final months of the war. Material shortages, particularly high-quality steel and submarine batteries, were acute, as resources were preferentially allocated to larger Type XXI and XXIII U-boats deemed more strategically vital. Battery production, essential for the electric-powered Seehund, was crippled by a British bombing raid on the AFA Hagen plant on the night of 1-2 December 1944, which destroyed over eight completed sets for advanced U-boats and numerous torpedo batteries, delaying deliveries for midget submarines including the Seehund. Allied strategic bombing campaigns further disrupted key manufacturing sites, such as the Germaniawerft yard in Kiel, a primary Seehund builder that endured repeated heavy raids targeting its submarine assembly facilities. Labor shortages compounded these issues, as the intensification of under total war mobilization in 1944 depleted skilled workers from shipyards and related industries, forcing reliance on less efficient forced labor pools. Despite the Seehund's simple design enabling relatively low production costs—far below the 4-5 million Reichsmarks required for a full-sized Type VIIC —these wartime impediments limited the program's scale and prevented it from achieving its intended mass deployment.

Operational history

Training and initial deployments

The training of Seehund crews was primarily conducted at the Lehrkommando 300 base in Neustadt/Holstein, utilizing Hecht prototypes as stand-in vessels to familiarize operators with handling. These prototypes, built between May and August 1944, allowed crews to practice essential maneuvers without risking operational Seehunds. In April 1945, training shifted to . The program spanned eight weeks and emphasized coordination between the two-man crews—one commander and one engineer—drawn from volunteers among watch officers, midshipmen, coxswains, and senior ratings with strong mechanical aptitude for onboard maintenance. Instruction covered navigation over multi-day voyages and torpedo-firing drills using support ships like the and Frida Horn, building the teamwork required for the submarine's confined quarters. By early , sufficient personnel had completed training to support initial flotillas, though high attrition rates demanded ongoing recruitment. The first Seehund flotilla, designated K-Flotilla 312, formed in December 1944 at in the , with six boats arriving on December 24 and eighteen more by month's end. On December 31, 1944, eighteen Seehunds departed for a trial run to test transit capabilities toward Allied shipping lanes off the estuary. However, a severe storm scattered the formation, resulting in the loss of sixteen boats to rough seas and sandbanks, with two returning intact. IJmuiden served as the primary operational hub, featuring concealed infrastructure such as a on the Hoogoven , moorings in the protected central lock, and unheated in nearby Driehus and Velsenbeck Park to shield against raids. Logistics focused on efficient resupply, with dedicated facilities for loading the 533 mm G.7e torpedoes externally and fueling the 60-horsepower diesel and electric motors, often under cover of night to minimize detection. This disastrous trial underscored the Seehund's acute vulnerability to adverse weather, prompting command to delay further deployments until February 1945, when calmer conditions allowed for resumed preparations. Early evaluations stressed the need for improved and crew endurance in cold, damp environments, influencing subsequent operational protocols.

Combat missions and successes

The Seehund midget submarines primarily undertook short coastal sorties launched from ports in and occupied , such as , , and , penetrating into the to interdict Allied convoys bound for the invasion fronts. These missions emphasized rapid deployment and return, with patrols generally lasting 3 to 5 days due to limited , focusing on ambush tactics against merchant shipping in shallow, mine-infested waters near the and off . Operational activity intensified from January to April 1945, culminating in a total of 142 sorties despite intensifying Allied air and naval patrols. The first success occurred on 2 January 1945, when a Seehund sank the 324-ton trawler Hayburn Wyke off Ostend. Subsequent key operations included the sinking of the 941-ton cable ship Alert on 24 February by U-5330 off Ramsgate and coordinated attacks on convoys in March, such as the sinking of the 2,878-ton collier Taber Park on 13 March by an unidentified Seehund near the Elbow Buoy. Across these missions, Seehunds sank 8 totaling 17,301 gross register tons and damaged 3 others for 18,384 tons, though German claims credited them with approximately 93,000 GRT sunk while British postwar assessments confirmed about 20,000 GRT. Notable successes targeted tankers and supply ships, including the 7,219-ton tanker Samida (sunk 21 ) and the 1,556-ton freighter Newlands (sunk 22 ), disrupting fuel and flows to the . In late-war desperation, Seehunds adapted for non-combat roles, including two special resupply missions to the besieged German garrison at on 28 April and 2 May 1945; torpedoes were replaced with modified containers dubbed "butter torpedoes" to deliver food, ammunition, and mail, with at least one successful delivery despite rough seas. Tactically, crews relied on night ambushes, employing the three-meter for visual targeting and hydrophones for detecting propeller noise in the noisy coastal environment, while evasion maneuvers exploited the submarine's small size and shallow draft to hug and mudflats beyond depth-charge reach.

Losses and operational evaluation

Out of the 138 Seehund submarines commissioned by the , 35 were lost during operations, resulting in an attrition rate of approximately 25% among active boats. The primary causes of these losses were conditions, which accounted for around 20 incidents, followed by mechanical failures including battery shorts and hull leaks that compromised seaworthiness. Allied countermeasures played a minimal role, with only a few losses attributed to depth-charge attacks or other direct enemy actions. Notable among the weather-related incidents was the initial deployment on 31 December 1944, when 18 Seehunds departed from in the ; a gale-force led to the loss of 16 boats through capsizing or drifting ashore, with just two returning to base. Additional losses occurred due to grounding on coastal shallows or deliberate self-destruction by crews to prevent capture by advancing Allied forces. Operationally, the Seehunds conducted 142 sorties between January and , achieving a modest tactical record by sinking 8 Allied totaling 17,301 gross register tons and damaging 3 others for 18,384 tons, yet their overall strategic impact remained negligible amid the collapsing German . Limitations in range (approximately 300 nautical miles surfaced) and vulnerability to rough seas curtailed their utility, diverting significant Allied resources but failing to alter the course of the naval campaign. Compared to predecessors like the Biber midget submarine, which suffered high mechanical unreliability and few successes, the Seehund demonstrated greater reliability and combat potential, though it was less cost-effective than human torpedoes like the Neger for short-range missions. Seehund operations effectively ended on 28 April 1945 following the last sorties to resupply isolated garrisons, with the broader German surrender on 8 leading to approximately 100 boats being surrendered intact to Allied forces.

Post-war use and survivors

Captured submarines and foreign service

Following the German surrender in , Allied forces captured numerous midget submarines from German naval bases, shipyards, and unfinished production lines across . The recovered several intact examples during the final weeks of the and immediately after. The obtained several captured Seehund submarines for technical evaluation and performance trials in the post-war period, focusing on their stealth, maneuverability, and potential adaptations for coastal defense roles. These assessments contributed to early studies on vulnerabilities, with joint exercises involving French-operated Seehund units conducted in U.S. waters as late as 1953 to simulate harbor attack scenarios. The received four Seehund submarines as reparations through a 1945 mission to that secured 25 U-boats of various types overall; these were refitted, renumbered S621 through S624, and commissioned into service in 1946. Employed primarily for coastal patrol duties and crew training in the Mediterranean, the vessels underwent minor modernizations to extend their operational viability before being decommissioned by 1953, with S622 serving until 1956 owing to technological obsolescence and the arrival of more advanced French designs. Captured Seehund submarines saw limited repurposing beyond initial evaluations, with some utilized as targets for practice or converted for underwater salvage operations to recover wartime wrecks. No other nations integrated the type into active military service, though Allied testing programs drew lessons from their compact design for subsequent prototypes during the early era.

Preserved examples and legacy

Several Seehund midget submarines have survived and are preserved in museums around the world, serving as tangible reminders of late-war German naval innovation. One notable example is S 622, a captured vessel displayed at the in , where its exterior has been restored for public viewing. Similarly, U-5075, a training model brought to the for evaluation, stands as a static exhibit at the United States Naval Museum in , highlighting Allied assessments of captured technology. In Germany, multiple institutions house intact or restored Seehund examples, emphasizing their engineering and historical context. The features a complete specimen recovered from coastal waters, showcasing its compact design and operational mechanisms. The in displays a Seehund salvaged from the near in 1958, allowing visitors to explore its internal layout through a . At the Deutsches Marinemuseum in , another example forms part of the artifacts collection, underscoring the Kriegsmarine's final desperate measures. The German Maritime Museum in holds a restored Seehund, salvaged and refurbished in the 1970s by local shipbuilders, which was temporarily relocated during museum renovations in 2019. Additionally, the Wehrtechnische Studiensammlung ( Museum of German Defense Technology) in exhibits a Seehund as part of its naval technology collection, focusing on its tactical role. Recent archaeological efforts have added to the preserved inventory. In April 2002, the wreck of U-5095 was raised by the Royal Dutch Navy and a civilian team from a beach near , , after it had been buried in sand since ; the remains, including disarmed torpedoes, are now displayed at a local Atlantikwall museum. Other partial wrecks, such as rusted hulks in the , remain unrecovered due to environmental challenges, though they fuel ongoing WWII submarine archaeology projects. The Seehund's legacy endures as a symbol of Germany's late-war improvisation amid resource shortages, representing both engineering ingenuity and the futility of asymmetric tactics against superior Allied forces. Captured examples briefly influenced post-war development, notably contributing to the design of the U.S. Navy's X-1 experimental submarine in the early era, which drew on Seehund operational data for coastal defense concepts. Featured in naval histories and media, the type exemplifies flawed yet innovative engineering, with preserved vessels educating on the human and technological costs of .

References

  1. https://www.uboat.net/types/seehund.htm
  2. http://www.uboataces.com/midget-seehund.shtml
  3. https://www.historic-uk.com/HistoryUK/HistoryofBritain/D-Day-X-Craft/
  4. https://www.usni.org/magazines/naval-history-magazine/2023/august/smallest-boat
  5. https://www.bsac.com/document/german-sub-seehund-project-report/2013-german-sub-seehund.pdf
  6. http://www.one35th.com/seehund/sh_history.htm
  7. https://ww2db.com/ship_spec.php?ship_id=865
  8. https://naval-encyclopedia.com/ww2/germany/german-mini-subs-and-human-torpedoes.php
  9. http://www.uboataces.com/midget-hecht.shtml
  10. http://www.one35th.com/seehund/sh_develop.htm
  11. https://warhistory.org/@msw/article/the-pocket-u-boat-seehund-part-i
  12. http://www.german-navy.de/kriegsmarine/ships/uboats/minisubs/seehund/
  13. http://www.one35th.com/seehund/sh_armament.htm
  14. https://www.militaryfactory.com/ships/detail.php?ship_id=Type-XXVII-Seehund
  15. https://navyhistory.au/occasional-paper-26-salvage-of-the-german-seehunde-midget-submarine/
  16. https://www.usni.org/magazines/proceedings/1961/march/weapon-came-too-late
  17. https://uboat.net/technical/batteries.htm
  18. https://www.tracesofevil.com/search/label/Kiel
  19. https://ghdi.ghi-dc.org/sub_document.cfm?document_id=1559
  20. https://naval-encyclopedia.com/ww2/germany/type-viic-class.php
  21. https://uboat.net/ops/midget.htm
  22. https://www.uboat.net/ops/midget.htm
  23. https://uboat.net/allies/warships/ship/6960.html
  24. https://warhistory.org/@msw/article/the-pocket-u-boat-seehund-part-iii
  25. http://www.one35th.com/seehund/sh_operation.htm
  26. https://www.history.navy.mil/research/library/online-reading-room/title-list-alphabetically/w/war-damage-reports/submarine-report-vol1-war-damage-report-no58.html
  27. https://www.usni.org/magazines/proceedings/1946/february/too-little-too-late
  28. https://www.usni.org/magazines/proceedings/1947/june/german-submarine-war
  29. https://www.usni.org/magazines/proceedings/1966/february/french-submarine-force
  30. http://www.netmarine.net/bat/smarins/seehund/photo03.htm
  31. http://www.juergenthuro.de/html/u-5075.html
  32. https://speyer.technik-museum.de/de/kleinstunterseeboot-seehund
  33. https://www.uboat.net/special/museums/site/16.html
  34. https://www.europeremembers.com/pois/316/german-naval-museum
  35. https://www.dsm.museum/en/museum/exhibition-themes/german-submarines-technology-fascination-and-terror
  36. http://www.juergenthuro.de/html/seehundko.html
  37. https://www.uboat.net/boats/midget_5095.html
  38. https://www.twz.com/the-navy-procured-this-midget-submarine-for-coastal-defense-during-the-cold-war
  39. https://snr.org.uk/the-mariners-mirror-podcast/nazi-midget-submarine-seehund/
Add your contribution
Related Hubs
User Avatar
No comments yet.