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U-1105: The Black Panther, The World’s Most Accessible U-Boat

Explorer and maritime historian Erik Petkovic details the development, history and eventual demise of Germany’s U-1105, which represented the cutting edge of the arm’s race between subsea hunters and the hunted during WWII. Resting in the brackish waters of the Potomac River near Piney Point, Maryland, USA, the U-1105 is the most accessible sunken U-boat along the US East Coast.

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by Erik Petkovic

All photos by Erik Petkovic unless otherwise noted.

U-1105 was a highly modified Type VIIC nicknamed the Black Panther.

In the infancy of 1942, the American shoreline was ablaze and its waters ran red with blood and black with oil. Operation Paukenschlag (Drumbeat) had just commenced. The mastermind of Paukenschlag, Admiral Karl Donitz, authorized five Type VII U-boats to unleash hell in American waters. 

Reinhard Hardegen, commander of U-123, and his fifty-one man crew were in one of the U-boats assigned to Paukenschlag. Although unknown at the time, the world would know who he was in short order as he took aim at a tanker from 4 km/4,400 yards. U-123 hit the tanker with multiple torpedoes and sank Norness off New York. When Americans awoke to the headlines the next day, America would never be the same, and neither would the American psyche. This was the second time in five weeks (Pearl Harbor was attacked on December 7, 1941) and the second time since the War of 1812 that America was attacked on its home soil. 

Paukenschlag was a massive success from the Kriegsmarine perspective. From the Allied perspective, it was massively destructive. Paukenschlag was just the initial onslaught. The drum continued to beat long after Donitz’ five U-boats returned home. In the first seven months of 1942, 109 ships were lost in American waters along with 2,081 mariners. 

To combat the significant loss of life and vessel, the Allies—through ingenuity and engineering—developed three keys to turning the Battle of the Atlantic. The first was High Frequency Direction Finder aka “Huff-Duff”. Although this technology was not new (as the ability to locate low frequency bearings had been used for years) the British were able to tune the technology to be able to take bearings on high frequencies when U-boats surfaced to transmit weather reports or to coordinate wolf pack attacks. 

The second advancement—breaking the secret code of the German Enigma machine—was arguably the most significant. The painstaking work by Alan Turing and those at Bletchley Park not only turned the tide of the Battle of the Atlantic, but of World War Two.

The further development of ASDIC, named after the Anti-Submarine Detection Investigation Committee, proved an effective weapon against the Grey Wolves. Known as SONAR to the Americans, ASDIC evolution was war-changing. The hunters became the hunted. 

These advancements were so effective that while 109 ships were lost in American waters in the first half of 1942, zero vessels were lost in the second half of the year. As a result, U-boats were being obliterated at an alarming pace. The horrific U-boat losses caused a change in tactics: Donitz recalled the U-boats from the western Atlantic, the Kriegsmarine shifted back to lone wolf operations from wolf pack attacks, and the Allied advancements necessitated new U-boat design and engineering. Enter U-1105.

A view off the port bow of U-1105 in dry dock. Alberich tiles can be seen attached to the hull.

Construction

When U-1105 was launched on April 20, 1944, (Hitler’s 55th birthday) World War Two was a year from being over. The “Happy Times” had long since disappeared. The wolves were being slaughtered in high numbers. By the end of the war, the casualty rate for Kriegsmarine submariners was nearly 75%—upwards of 28,000 sailors and nearly 800 U-boats would be lost. 

The Germans built seven varieties of Type VII U-boats. Of the 709 Type VII U-boats completed, 577 were Type VIIC, including U-1105. However, U-1105 was not a typical Type VIIC. U-1105 was a highly modified Type VIIC with the latest in German engineering.

Alberich

The Kriegsmarine attempted to counter the effect SONAR was having on their disappearing U-boat fleet. The Germans developed a synthetic rubber material which absorbed and dispersed sound waves—in effect, they engineered an acoustic camouflage dubbed Alberich.

An early form of stealth technology, Alberich tiles were engineered with different patterns of holes perforating the rubber which allowed the rubber to absorb the sound pinging them by SONAR from Allied ships. Similar to the tiles on the space shuttle decades in the future in which tiles were specifically engineered for a certain part of the space shuttle, specific hole patterns were engineered for specific parts of the U-boat.

Studies showed Alberich could reduce the likelihood of detection by up to sixty percent. Despite the technological and engineering innovation further enhanced by successful trials, only thirteen U-boats were outfitted with Alberich. U-1105 was one of only four U-boats outfitted with Alberich that went on a war patrol. 

A tile of Alberich from U-1105’s conning tower. Each tile contained a unique set of holes to absorb sound waves – an early form of stealth technology.
A sheet of Alberich can be seen peeling away from U-1105’s hull.

GHG Balkon

Early U-boats were outfitted with a passive sonar array called Gruppenhorchgeraete (GHG). The GHG was placed just aft of the torpedo tubes on either side of the bow containing a dozen hydrophones which helped the U-boat listen to underwater sounds and decipher Allied propellers.

Limitations with GHG lead to the development of the GHG Balkon—an advanced listening system with 48 hydrophones. The GHG Balkon increased the effective range of the U-boat’s listening capability by an astounding 70 percent. The system was so effective sounds could be heard over the horizon. U-1105 was one of nearly two dozen U-boats to be equipped with GHG Balkon. 

The GHG Balkon – an active sonar array containing 48 hydrophones – was a significant upgrade which allowed U-Boats to hear sounds over the horizon. The GHG was so effective it was immediately copied by the Allies and placed on submarines.

Schnorkel

U-boats had two ways of operating – either by electric, battery powered motors or by diesel engines. U-boats could not use the diesel engines while submerged; otherwise, the engines would suck all the air in the U-boat into the engines and the crew would suffocate.. Installation of a schnorkel allowed the U-boat to operate submerged while using the diesels.

The introduction of the schnorkel was more successful than any navy would have imagined. At the beginning of the war, U-boats could stay submerged for three days. By the end of the war, schnorkel technology had been perfected to allow a U-boat to stay submerged in excess of sixty days. This remained a record until the US Navy broke it in the 1970s, but only by use of nuclear power and after decades of Cold War engineering. 

A US Navy sailor testing a U-Boat schnorkel in the Chesapeake Bay in 1956. 

Black Panther

U-1105’s conning tower emblem depicted a black panther sprawling over the world. U-1105 commanding officer, Oberleutenant zur see Hans-Joachim Schwarz explained how U-1105 received its nickname: “The name and the heraldic figure were the result of a competition in the crew. A black panther is a beast of prey in the open country. In wartime, a U-boat is also a beast of prey that attacks ships on the surface. Because the boat was covered with a black rubber coat, we thought that the name was very suitable for U-1105.”

A starboard quarter view of U-1105’s conning tower and upper and lower wintergartens with automatic weapons prior to sea trials with the Royal Navy.

WAR

On April 12, 1945, U-1105 ventured out in the name of the Fatherland to the western approaches of Ireland—U-1105’s hunting grounds. Careful transit of the North Sea saw U-1105 arrive west of the Outer Hebrides on April23. Schwarz surfaced briefly to send a transmission to Befehlshaber der U-boote (BdU)—U-boat headquarters. The message was short and concise: “My position is AM 0213. Weak defense and patrol.” The U-boat was so close to shore the men could see advertisements, lights, and vehicles. No one knew U-1105 was there. 

U-1105 commanding officer Oberleutnant zur See Hans-Joachim Schwarz.

On April 27, 1945, HMS Conn, HMS Redmill, and HMS Rupert, members of the Royal Navy’s 21st Escort Group, were in Irish waters carrying sonobuoys to detect U-boats. U-1105 heard the noises of the three ships. At this time, HMS Conn picked up a sonar contact which was believed to be a U-boat, but was in fact an incoming torpedo from U-1105. Fifty-seconds after firing the T5, a massive explosion rocked HMS Redmill. U-1105 remained undetected.

U-1105 attempted to descend to 100 m/330 ft to escape what was believed would be an imminent and ferocious depth charge attack. The emergency descent quickly became uncontrolled with two tons of water in her ballast tanks. U-1105 hit bottom at 570 feet. U-1105 turned off its engines and sat on the bottom. Schwarz counted 299 depth charges dropped on U-1105. After 31 hours on the bottom while avoiding detection, U-1105 surfaced.

The crew of U-1105 poses on the conning tower and upper and lower wintergartens. The command staff stands on the main deck. Commander Schwarz in third from the right in the white hat. 

Surrender

Six days later U-1105 received the order to cease all combat. World War Two was over. U-1105 surrendered at Lisahally. En route, U-1105 destroyed all classified material, communications, and paper, including her log book. All torpedoes in the tubes were discharged overboard. Additionally, all ammunition and seals for the submarine’s weapons were dumped overboard. Ironically, U-1105 surrendered to the 21st Escort Group – the same group U-1105 attacked and killed 32 of its men when it torpedoed HMS Redmill

A previously classified drawing showing the placement of the 250 pound MK6 depth charge suspended beneath U-1105’s hull.

Testing & Evaluation

All U-boats surrendered at Lisahally, with the exception of U-1105, were destroyed per Operation Deadlight. Intelligence personnel knew from previous prisoner interrogations that Alberich existed and that the Allied forces were keen to start testing and evaluations. U-1105 was the one prize the US, British, and Soviet forces were interested in testing. The Americans were eager to get their hands on U-1105, but would have to wait until the Royal Navy completed their own trials and testing.

In January 1946, after a harrowing trek across the angry North Atlantic, U-1105 finally arrived in the United States and was authorized for salvage and explosives testing. At the conclusion of the proposed tests, U-1105 “shall be finally disposed of by sinking in waters of such depth as to assure a swept depth of at least fifty feet.”

U-1105 at detonation in the Potomac River.

Thirteen months of testing saw U-1105 sink five times. On September 19, 1948, at 1229 hours, a 113 kg/250 pound MK2 depth charge suspended 9 m/30 ft below U-1105’s conning tower was detonated. U-1105 sank in less than one minute for the sixth and final time. 

US Navy personnel arming the MK6 depth charge.

Diving U-1105

U-1105 rests at a depth of 28m/91 ft in the brackish waters of the Potomac River off Piney Point, Maryland—the most accessible sunken U-boat along the US East Coast. U-1105’s bow points south toward the Chesapeake Bay. The wreck sits in an area with heavy commercial shipping traffic. Not only is the wreck easily accessible, but from April to November the wreck is easy to locate—a buoy marks the site.

Original drawing of U-1105 embedded in the bottom of the Potomac River by James Christley in 1991. Starboard bow orientation. Courtesy NPS. 

The buoy is marked with several advisories including: POOR VISIBILITY, STRONG CURRENTS and US NAVY PROPERTY OBJECT REMOVAL PROHIBITED.

A small diver ball is tied directly to the top of the conning tower at a depth of 20 m/65 feet. The line is usually secured around the base of either the attack periscope or sky periscope. Free descents or hot drops are not advisable on this wreck. With the limited visibility and a seemingly ever present current, one would not be guaranteed to see the wreck if a free descent was performed. It is recommended to dive the wreck based on tide tables, with the best conditions being at or near slack high tide. 

The fall and winter months allow for better visibility, less pleasure boat traffic, and fewer jellyfish. Visibility can double or triple in the winter months (2-3.5m/6-12 ft) compared to the summer months (1-1+m/3-4 ft).

The gun mounts are all that remain of U-1105’s 2cm Flak.

The Potomac quickly turns various hues of mundane color – greenish-brown, then brown, then shades of black. Regardless of color, it is murky. Vertical visibility is almost always better than horizontal visibility. As you approach the 18 m/60 ft mark in the black water, the faint outline of the top of the conning tower comes into view. The most prominent feature is the sky periscope housing and mount which projects above the conning tower.

Other features in the conning tower include original teakwood, attack periscope mount, diesel engine air intake, and housing for the FuMO Hohentwiel radar. The large 2 cm watertight ammunition container is located at the entrance to the upper Wintergarten. The Flak 38 gun mounts can be seen bolted to the original wood decking. 

The hinge and cap are still in place on the storage tube which once housed U-1105’s colors. 
U-1105’s 2cm ammunition container at the aft end of the conning tower.

The diver will continue aft along the starboard side of the upper Wintergarten and drop onto the lower Wintergarten. Immediately to the diver’s left is the external watertight storage tube. This is where U-1105’s flags were stored. Two 3.7mm watertight ammunition containers and the M42 automatic machine gun mount can be viewed.

Teak decking can still be seen on the lower Wintergarten. 
U-1105’s sky periscope mount protrudes from the conning tower.

There are some interesting features to see while dropping down along the main deck and circumnavigating the superstructure. Below the sky periscope, flaring out from the conning tower on the right (while looking aft), is the rectangular base for the schnorkel. This is where the schnorkel would clamp into the conning tower when deployed. Along the starboard side of the conning tower is the exhaust trunking. This intricate piping is a very unique piece of maritime history, as this is one of very few sunken U-boats in the world where this can be seen. 

Alberich can be seen in a multitude of places on and around the superstructure including the conning tower, both Wintergartens and saddle tanks. In 2009, the U-1105 Black Panther Historic Shipwreck Preserve was included on the inaugural list of the National Oceanic and Atmospheric Administration’s National System of Marine Protected Areas. 

Additional Resources

US Naval Institute: “To Hell, By Compass: The Remarkable Wreck and Rescue of USS S-5”
by Erik Petkovic

Osprey Publishing: German submarine U-1105 ‘Black Panther’ THE NAVAL ARCHAEOLOGY OF A U-BOAT

Wikipedia: German submarine U-1105


Erik Petkovic is an explorer, author, maritime historian, shipwreck researcher, and technical wreck diver. Erik is the author of multiple wreck diving and maritime history books. Erik has been featured in publications worldwide and is a consultant for various production companies. Erik regularly presents at the largest dive shows and museums and is a sought after presenter due to his unique storytelling and in-depth research. He currently lives in Southern Maryland with his wife and sons. ErikPetkovic.com

History

Mine Over Monitor: Iconic dive sites with a shared history

What does Sweden’s flooded Långban mine—a wellspring of u/w exploration and mapping for more than 16 years—have to do with the famed Civil War ironclad, the USS Monitor that figured prominently in the history of tech diving? Finnish Scientific Diving Academy coordinator Edd Stockdale takes us for an improbable dive into history!

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by Edd Stockdale. Images by Edd Stockdale unless otherwise noted. Header image: USS Monitor. Watercolor by Oscar Parkes, public domain.

In the center of Sweden is a region known as Bergslagen featuring—due to its hugely diverse mineralogy—hundreds of years of mining history. The region boasts many abandoned mines (some flooded, others not) in addition to active sites. One specifically stands out with regards to its geology and, in terms of diving, its connection to an iconic US dive location.

Långban (pronounced long-ban), a three-and-a-half hours westward drive from Stockholm, is both the name of the village and the mine where extraction began as early as the 1500s. Mining activity grew dramatically in the mid 1700s and continued until 1972 when the mine closed. With the pumps shut off, the lakes on both sides flooded the mine. 

In geological terms, the mine features one of the highest recorded diversities of minerals found in a single working site, with over 270 unique minerals identified—70 of which are unique to Långban itself.

Old mine office building, birthplace of J. Ericsson and now divers accommodation.
Old mine office building, birthplace of J. Ericsson and now divers accommodation.

These days, the village is home to the Långban Mining Museum and residents, some of whom were once miners there. Underneath the surface, clear water floods the entire mine, preserving the structures and all evidence of industrial mining and providing a stunning diving locale. 

Around 2005, divers began exploring the mine. In conjunction with the museum, divers formed the Långban Dyksällskap (diving association). They allowed access to the site and documented their efforts to promote a wider understanding of the site for visitors. Documentation included videos for general access around the museum site, photos of specific sections of interest for displays, and—more recently—early 3D models from photogrammetry. 

Year round, the mine features a 6°C/43°F water temp and visibility up to 40 m/131 ft, making it ideal for diving. Plus, the mine is open to all qualified divers interested in the industrial history of the area. 

Diving Access

To facilitate better access, divers have spent the last 16 years working in the shallow areas to establish a main line system and are—slowly, but surely—mapping the mine’s deeper levels with work still continuing at 90 m/295 ft and onward. Due to historical laws that required mapping of all mining activities in the country, there is a publicly accessible record of Swedish mines—including Långban—which provides preliminary information for possible routes. While they’re far from accurate, the guides still offer a great insight into areas of interest.

The 36m/120 ft level of the New Shaft.
The 36m/120 ft level of the New Shaft.Photo by Anders Torstensson
A wagon on the 21m/70 ft level is a iconic spot for divers to visit
A wagon on the 21m/70 ft level is a iconic spot for divers to visit
Old chains hanging down in the 'Hellraiser Room.
Old chains hanging down in the ‘Hellraiser Room.’ Photo by Erik Matteusson

Diving in the shallow levels, divers often encounter early working areas, particularly those accessed in the major boom period of the mid 1700s. Artifacts from that time are still present. Deeper explorations reveal more recent mining activities where the techniques and mineralogy change. Above ground, visitors can explore many of the still-standing towers and buildings preserved by the museum, providing additional context for the diving activities below. 

The old mine offices are one such building; they served as the early diving association’s lodgings, and are connected to another iconic diving site—the USS Monitor. Långban was the birthplace of John (Johan) Ericsson in 1803, and his father and grandfather both held the position of mine supervisor.

Fathers of Invention

John Ericsson
John Ericsson
1803-1889

Due to financial difficulties, Ericsson’s father was forced from the position—and Långban. John Ericsson and his brother, Nils, followed their father to the excavation of the Göta Canal where they were quickly recognized for their extraordinary potential in engineering and surveying. After a surveying career in the Swedish military, Ericsson developed an interest in heat engines, moving to England in 1826 to establish himself as an inventor. Initial work on engines led to an interest in locomotives—both Ericsson and John Braithwaite entered The Rainhill Trials with the Novelty locomotive engine. 

Ericsson developed efficient engines for ships—with success—in the years to follow. In 1835, he designed a screw propeller that was more efficient than the contemporary paddle steamers, but it was viewed with resistance from the British Navy Admiralty in the 1837 demonstration trials. As a result, Ericsson relocated to New York where there was more interest in his designs—especially by American Captain Robert Stockton, who lobbied for funding to build the US Navy’s first ship powered by a screw propeller, the USS Princeton. 

Image from U.S. National Archives and Records Administration, public domain.

The USS Princeton launched in 1843 after three years under construction, during which time relations between Stockton and Ericsson had soured. On February 27, 1844, a public reception was hosted by President Tyler during which The Princeton departed Alexandria, Virginia, on an exhibition cruise down the Potomac. Present were the President, members of his cabinet, and approximately 400 dignitaries, including Stockton.

In order to impress his guests, Stockton decided to fire the ship’s largest long gun, named Peacemaker, which he had designed and reportedly rushed into production without adequate testing, based on one of Ericsson’s innovative designs for a smaller gun. After three successful firings during the trip downriver, the gun was reloaded for a final salute to George Washington as the ship passed Mount Vernon on the return trip. However, when Stockton pulled the firing lanyard, the gun exploded and instantly killed six men, including the Secretary of State and Secretary of the Navy. Another 16-20 people were injured.

Though Stockton had built the gun based on an incorrect implementation of Ericsson’s original design, Ericsson was blamed for the tragedy, and spent many years trying to clear his name. He parted ways with the US Navy the following year, successfully dedicating himself to civilian developments. In the early 1850s, during the war between France and Great Britain, Ericsson submitted designs for a new type of armored ship to the French who declined. His invention was shelved until the outbreak of the American Civil War in 1861. 

The Rise of the Ironclads

In response to the Confederacy’s conversion of the USS Merrimac into an Ironclad (eventually christened CSS Virginia), President Lincoln authorized the development of the Ironclad Board to develop a counter. He was impressed with Ericsson’s original ironclad designs intended for the French, and acquaintances and invested parties helped Ericsson and the Navy navigate their mutual distrust. Construction began in October 1861, and the ship launched on January 30, 1862. 

Diagram of USS Monitor.
Diagram of USS Monitor. Wiki Commons, public domain.

The design resulted in a floating battery, named the USS Monitor, with the first rotating gun turret that earned its place in history at the Battle of Hampton Roads on March 8 – 9, 1862, the first battle between ironclads against the CSS Virginia. Though the battle ended in a stalemate after three hours with no significant damage inflicted, the impact of this battle changed naval design and warfare thereafter, with wooden warships being abandoned in favor of ironclads across large numbers of shipyards. 

USS Monitor. Watercolor by Oscar Parkes
USS Monitor. Watercolor by Oscar Parkes, public domain.

In support of the Union Army along the James River in the Peninsula Campaign, the Monitor was ordered to North Carolina. On December 31, 1862, she foundered while being towed, sinking along the way off of Cape Hatteras, resulting in the loss of 16 crew members. 

The wreck was discovered in 1973 by a team led by John G. Newton from Duke University and was confirmed in 1974, finally being recognised as the first US Marine Sanctuary in 1975. It later became the source of a legal battle launched by wreck diver and historian Gary Gentile, for the rights of technical divers to dive the site on scuba.

Work by NOAA and Mariners Museum, Newport, over the following 30 years resulted in documentation of the site and identification of artifacts around the wreckage like the turret, deck guns, and other components of the wreck. In more recent explorations, divers have used 3D photogrammetry to construct a model for use by the general public.

The model of a monitor ship.
The model of a monitor ship. US Government, public domain.
USS Monitor shipwreck in Monitor National Marine Sanctuary.
USS Monitor shipwreck in Monitor National Marine Sanctuary. Photo: NOAA, public domain.

John Ericsson became a national hero and continued his production of ironclads, later moving into torpedo designs. He developed the torpedo vessel Destroyer, and undertook numerous other inventions until his death on March 8, 1889 in New York City. His remains were transported back to Sweden after a large memorial service in New York and interred in the town of Filipstad, 20 km/12 miles from his birthplace in Långban, 63 years after his departure. 
Two of the Monitor’s guns mark his memorial on the edge of the lake in town. Anyone visiting the region can visit the Långban museum, which has a section dedicated to the USS Monitor along with replicas of the vessel herself that used to float on the lake.

Replica model of the USS Monitor turret at the museum
Replica model of the USS Monitor turret at the museum
Replica gun of the USS Monitor 
Replica gun of the USS Monitor 

Exiting the door of the house he was born in on the way to dive the Långban mine, every diver will see the name on the commemorative memorial in the square showing the great connection between a small village in Sweden, above a unique mine, and one of the greatest Naval developments.

Commemorative memorial of John Ericssons birth in Långban
Commemorative memorial of John Ericssons birth in Långban

Additional Resources

Fourth Element: Diving the USS Monitor by Joe Hoyt

InDepth: Out of the Depths: The Story of British Mine Diving by Jon Glanfield

NOAA (photogrammetry): Getting a Clear View of the USS Monitor

Gary Gentile Productions: Ironclad Legacy: Battles of the USS Monitor 

Gary Gentile Productions: The Battle for the U.S.S. Monitor (DVD)

Other Stories by Edd Stockdale:

InDepth: The Swan—A 17th Century Story at the Bottom of the Baltic Sea by Edd Stockdale

InDepth: Finland’s Newly Established Scientific Diving Academy by Edd Stockdale


Edd Stockdale has worked in scientific and technical diving for over a decade and joined as Badewanne team member in 2019. He is the coordinator of the newly established Finnish Scientific Diving Academy at the University of Helsinki which was established to develop scientific diving training to further research abilities and develop new approaches to data collection in cold water based science. 
When not working on research diving, Edd can be found exploring the mines and wrecks in the Nordic region or planning the next adventure. He is supported by Divesoft as well as Santi, Halcyon, and REEL Diving in Scandinavia. 

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