On July 12, 2006 RV St. Barbara, a ship belonging to the Polish oil company Petrobaltic found a 265 m long wreck which they thought was most likely Graf Zeppelin.
On July 26, 2006 the crew of the Polish Navy’s survey ship ORP Arctowski commenced inspection of the wreckage to confirm its identity, and the following day the Polish Navy confirmed that the wreckage was indeed that of Graf Zeppelin. She rests at more than 87 meters (264 feet) below the surface.
Wilhelm Hadeler had been Assistant to the Professor of Naval Construction at the Technical University of Berlin for nine years when he was appointed to draft preliminary designs for an aircraft carrier in April 1934.
The Anglo-German Naval Agreement signed 18 June 1935 allowed Germany to construct aircraft carriers with displacement up to 38,500 tons.
In 1935, Adolf Hitler announced that Germany would construct aircraft carriers to strengthen theKriegsmarine.
A Luftwaffe officer, a naval officer and a constructor visited Japan in the autumn of 1935 to obtain flight deck equipment blueprints and inspect the Japanese aircraft carrier Akagi .
The keel of Graf Zeppelin was laid down the next year. Two years later, Großadmiral Erich Raeder presented an ambitious shipbuilding program called Plan Z, in which four carriers were to be built by 1945. In 1939, he revised the plan, reducing the number to two.
Having no experience building such ships, the Kriegsmarine had difficulty implementing advanced technologies such as steam-driven catapults into the Graf Zeppelin.
German designers were able to study Japanese designs, but were constrained by the realities of creating a North Sea carrier vs. a “Blue Water” design.
Several cruiser-type guns were envisioned to allow commerce raiding and defense against British cruisers, for example.
This is in contrast to American and Japanese designs, which were more oriented toward a task-force defense, using supporting cruisers for surface firepower.
Graf Zeppelin’s hull was divided into 19 watertight compartments, the standard division for all capital ships in the Kriegsmarine.
Her belt armor varied from 100 mm (3.9 in) over the machinery spaces and aft magazines, to 60 mm (2.4 in) over the forward magazines and tapered down to 30 mm (1.2 in) at the bows.
Stern armor was kept at 80 mm (3.1 in) to protect the steering gear. Inboard of the main armor belt was a 20 mm (0.79 in) anti-torpedo bulkhead.
Horizontal armor protection against aerial bombs and plunging shellfire started with the flight deck, which acted as the main strength deck.
The armor was generally 20 mm (0.79 in) thick except for those areas around the elevator shafts and funnel uptakes where thickness increased to 40 mm (1.6 in) in order to give the elevators necessary structural strength and the critical uptakes greater splinter protection.
Beneath the lower hangar was the main armored deck (or tween deck) where armor thickness varied from 60 mm (2.4 in) over the magazines to 40 mm (1.6 in) over the machinery spaces.
Along the peripheries, it formed a 45 degree slope where it joined the lower portion of the waterline belt armor.
Graf Zeppelin’s original length-to-beam ratio was 9.26:1, resulting in a slender silhouette.
However, in May 1942, the accumulating top-weight of recent design changes required the addition of deep bulges to either side of her hull, decreasing that ratio to 8.33:1 and giving her the widest beam of any carrier designed prior to 1942.
The bulges served mainly to improve Graf Zeppelin’s stability but they also gave her an added degree of anti-torpedo protection and increased her operating range because selected compartments were designed to store approximately 1500 tons more fuel oil.
Graf Zeppelin’s power plant consisted of 16 La Mont high-pressure boilers, similar to those used in the Admiral Hipper-class heavy cruisers.
Her four sets of geared turbines, connected to four shafts, were expected to produce 200,000 shp (150,000 kW) and propel the carrier at a top speed of 35 knots (40 mph; 65 km/h).
With a maximum bunkerage capacity of 5000 tons of fuel oil (prior to the addition of bulges in 1942), Graf Zeppelin’s calculated radius of action was 9,600 miles (15,400 km) at 19 knots (35 km/h; 22 mph), though wartime experience on ships with similar powerplants showed such estimates were highly inaccurate.
Actual operational ranges tended to be much lower.
Two Voith-Schneider cycloidal propeller-rudders were installed in the forward bow of the ship along the center-line.
These were intended to assist in berthing the ship in harbor and also in negotiating narrow waterways such as the Kiel Canal where, due to the carrier’s high freeboard and difficulty in maneuvering at speeds below 8 knots (15 km/h; 9.2 mph), gusting winds might push the ship into the canal sides.
In an emergency, the units could have been used to steer the ship at speeds under 12 knots (22 km/h; 14 mph) and, if the ship’s main engines were rendered inoperable, could propel the vessel at a speed of 4 knots (7.4 km/h; 4.6 mph) in calm seas. When not in use, they were to be retracted into their vertical shafts and protected by water-tight covers.
Graf Zeppelin’s steel flight deck, overlaid with wooden planking, was 242 m (794 ft) long by 30 m (98 ft) wide at its maximum.
It had a slight round down right aft and overhung the main superstructure but not the stern; being supported by steel girders.
At the bow, the carrier had an open forecastle and the leading edge of her flight deck was uneven (mainly due to the blunt ends of her catapult tracks), but these did not appear likely to cause any undue air turbulence.
Careful wind-tunnel studies using models confirmed this. However, her long low island structure did generate a vortex over the flight deck in these tests when the ship yawed to port. This was considered to be an acceptable hazard when conducting air operations.
Graf Zeppelin had three electrically-operated elevators positioned along the flight-deck’s center-line: one near the bow, abreast the forward end of the island; one amidships; and one aft.
They were octagonal in shape, measuring 13 m (43 ft) x 14 m (46 ft), and were designed to transfer aircraft weighing up to 5.5 tons between decks.
Two Deutsche Werke compressed air-driven catapults were installed at the forward end of the flight deck for power-assisted launches.
They were 23 m (75 ft) long and designed to accelerate a 2,500 kg (5,500 lb) fighter to a speed of approximately 140 km/h (87 mph) and a 5,000 kg (11,000 lb) bomber to 130 km/h (81 mph).
A dual set of rails led back from the catapults to the forward and midship elevators. In the hangars, aircraft would have been hoisted by crane onto collapsible launch trollies.
The aircraft/trolley combination would then have been lifted to flight deck level on the elevator and trundled forward to the catapult start points.
As each plane lifted off, its launch trolley would have been caught in a metal “basket” at the end of the catapult track, lowered to the forecastle on “B” deck and rolled back into the upper hangar for re-use via a secondary set of rails.
The catapults could theoretically launch nine aircraft each at a rate of one every thirty seconds before exhausting their air reservoirs.
It would then have taken 50 minutes to recharge the reservoirs. When not in use, the catapult tracks could be covered with sheet metal farings to protect them from harsh weather.
Rolling take-offs would be performed only in an emergency or if the catapults were inoperable due to battle damage or mechanical failure.Whether this practice would have been strictly adhered to or later modified, based on actual air trials and combat experience, is open to question, especially given the limited capacity of the air reservoirs and the long recharging times necessary between launches.
One advantage of the system, however, was that it would have allowed Graf Zeppelin to launch and land aircraft simultaneously.
In this way, aircraft could have been brought up from the hangars and immediately catapulted off without any need for engine warm-up prior to launch.Once airborne, a pilot would have simply waited for his aircraft’s engine to attain normal operating temperature before switching back to the plane’s primary fuel tank.
Four arrester wires were positioned at the after end of the flight deck with two more emergency wires located afore and abaft of the amidships elevator.
Original drawings show four additional wires fore and aft of the forward lift, possibly intended to allow recovery of aircraft over the bows, but these may have been deleted from the ship’s final configuration.
To assist with night landings, the arrester wires were to be illuminated with neon lights. Two wind barriers were installed afore the midships and forward elevators.
Graf Zeppelin’s starboard-side island housed the command and navigating bridges and charthouse. It also served as a platform for three searchlights, four domed stabilized fire-control directors and a large vertical funnel.
To compensate for the weight of the island, the carrier’s flight deck and hangars were offset .5 m (1 ft 8 in) to port from her longitudinal axis.
Design additions proposed in 1942 included a tall fighter-director tower, air search radar antennas and a curved cap for her funnel, the latter intended to keep smoke and exhaust gases away from the armored fighter-director cabin.
Graf Zeppelin was armed with separate high and low angle guns for AA and anti-ship defense at a time when most other major navies were switching to dual-purpose AA weapons and relying on escort ships to protect their carriers from surface threats.
Her primary anti-shipping armament consisted of sixteen 15 cm (5.9 in) guns paired in eight armored casemates. These were mounted, two each, at the four corners of the carrier’s upper hangar deck, positions that raised the possibility the guns would be washed out in heavy seas, especially those in the forward casemates.
However, the Naval Armaments Office misinterpreted his proposal to save space by pairing them and instead doubled the number of guns to sixteen, resulting in a need for increased ammunition stowage and more electrically-operated hoists to service them.Later in her construction, some consideration was given to deleting these guns and replacing them with 10.5 cm (4.1 in) guns mounted on sponsons just below flight deck level.
But the structural modifications needed to accommodate such a change were judged too difficult and time-consuming, requiring major changes to the ship’s design, and the matter was shelved.
Primary AA protection came from twelve 10.5 cm (4.1 in) guns, paired in six turrets positioned three afore and three aft of the carrier’s island.
Potential blast damage to planes sited on the flight deck when these guns fired to port was an unavoidable risk and would have limited any flight activity during an engagement.
Graf Zeppelin’s expected role was that of a sea-going scouting platform and her initial planned air group reflected that emphasis: twenty Fieseler Fi 167 biplanes for scouting and torpedo attack, ten Messerschmitt Bf 109 fighters, and thirteen Junkers Ju 87 dive-bombers.
This was later changed to thirty Bf 109 fighters and twelve Ju 87 dive-bombers as carrier doctrine in Japan, Great Britain and the United States shifted away from purely reconnaissance duties towards offensive combat missions.
Construction on the Kriegsmarine’s two aircraft carriers had been fitful from the start due to a shortage of welders and delays in obtaining materials.
Work on Flugzeugträger B was finally halted on 19 September 1939 because, now that Germany was at war with England and France, priority had shifted to U-boat construction.
The hull, completed only up to the armored deck, sat rusting on its slipway until 28 February 1940, when Admiral Raeder ordered her broken up and scrapped.
Meantime, Germany’s conquest of Norway in April 1940 further eroded any chance of completing Flugzeugträger A (Graf Zeppelin).
Now responsible for defending Norway’s long coastline and numerous port facilities, the Kriegsmarine urgently required large numbers of coastal guns and AA batteries.
During a naval conference with Hitler on 29 April 1940, Admiral Raeder proposed halting all work on Graf Zeppelin, arguing that even if she was commissioned by the end of 1940, final installation of her guns would require another ten months or more (her original fire control system had been sold to the Soviet Union under an earlier trade agreement).
Hitler consented to the stop work order, allowing Raeder to have Graf Zeppelin’s 15 cm guns removed and transferred to Norway. The carrier’s heavy flak armament of twelve 10.5 cm guns had already been diverted elsewhere.
On 12 July 1940, Graf Zeppelin was towed from Kiel to Gotenhafen (Gdynia) and remained there for nearly a year.
Just prior to Germany’s invasion of the Soviet Union in June 1941, the carrier was again moved, this time to Stettin, in order to safeguard her from Soviet air attacks.
By November, the German army had pushed deep enough into Russian territory to remove any further threat of air attack and Graf Zeppelin was returned to Gotenhafen where she briefly served as a floating warehouse for the Navy’s hardwood supply.
British carriers had crippled the Italian fleet at Taranto in November 1940, critically damaged the German battleship Bismarck in May 1941 and prevented battleshipTirpitz from attacking two convoys bound for Russia in March 1942. In addition, a Japanese carrier raid on Pearl Harbor had devastated the American battlefleet in December 1941.
Raeder, anxious to secure air protection for the Kriegsmarine’s heavier surface units, informed Hitler that Graf Zeppelin could be finished in about a year, with another six months required for sea trials and flight training.
On 13 May 1942, with Hitler’s authorization, the German Naval Supreme Command ordered work resumed on the carrier.
But daunting technical problems remained. Raeder wanted newer planes, specifically designed for carrier use.
Reichsmarshall Goering, head of the Luftwaffe, replied that the already overburdened German aircraft industry could not possibly complete the design, testing and mass production of such aircraft before 1946.
Instead, he proposed converting existing aircraft (again the Junkers Ju 87 and Messerschmitt Bf 109) as a temporary solution until newer types could be developed. Training of carrier pilots at Travemünde would also resume.
Changes in naval technology dictated other alterations as well:installation of air search radar sets and antennas; upgraded radio equipment; an armored fighter director cabin mounted on the main mast (which in turn meant a heavier sturdier mast to accommodate the cabin’s added weight);
extra armoring for the bridge and fire control center; a new curved funnel cap to shield the fighter director cabin from smoke; replacing the single-mount 20mm AA guns with quadruple Flakvierling 38 guns (with a corresponding increase in ammunition supply) to improve overall AA defense; and additional bulges on either side of the hull to preserve the ship’s stability under all this added weight.
The German naval staff hoped all these changes could be accomplished by April 1943, with the carrier’s first sea trials taking place in August that same year.
Towards that end, Chief Engineer Hadeler was reassigned to oversee Graf Zeppelin’s completion.
Hadeler planned on getting the two inner shafts and their respective propulsion systems operational first, giving the ship an initial speed of 25-26 knots, fast enough for sea trials to commence and for conducting air training exercises. By the winter of 1943/1944 she was expected to be combat-ready.
On the night of 27–28 August 1942, Graf Zeppelin underwent the only Allied air attack ever specifically targeting her for destruction.
Nine RAF Lancaster bombers from 106 and 97 Squadrons were despatched against Gotenhafen, each one carrying single “Capital Ship” bombs, a 5,500 lb device with a shaped charge warhead intended for armoured targets.
One pilot was unable to see the carrier due to haze and instead dropped his bomb on the estimated position of the German battleship Gneisenau. Another believed he scored a direct hit on Graf Zeppelin but there is no known record of the ship suffering any damage from a bomb strike that night.
On 5 December 1942, Graf Zeppelin was towed back to Kiel and placed in a floating drydock. It seemed she might well see completion after all.
By late January 1943, however, Hitler had become so disenchanted with the Kriegsmarine, especially with what he perceived as the poor performance of its surface fleet, that he ordered all of its larger ships taken out of service and scrapped.
To Admiral Raeder, who had often clashed with Hitler on naval policy, this was a stunning setback. In a long memorandum to Hitler he called the new order “the cheapest sea victory England ever won”.
Raeder was shortly relieved of command and replaced with former Commander of Submarines Karl Dönitz.
Though Admiral Dönitz eventually persuaded Hitler to void most of the order, work on all new surface ships and even those nearing completion was halted, including Graf Zeppelin. As of 2 February 1943, construction on the carrier ended for good.
In April 1943 Graf Zeppelin was towed eastward, first to Gotenhafen, then to the roadstead at Swinemünde and finally berthed at a wharf in the Parnitz River, two miles from Stettin.
There she languished for the next two years with only a 40-man custodial crew in attendance. When Red Army forces neared the city in April 1945, the ship’s Kingston valves were opened, flooding her lower spaces and settling her firmly into the mud in shallow water.
A ten-man engineering squad then rigged the vessel’s interior with demolition and depth charges in order to hole the hull and destroy vital machinery.
At 6pm on 25 April 1945, just as the Russians entered Stettin, commander Wolfgang Kähler radioed the squad to detonate the explosives. Smoke billowing from the carrier’s funnel confirmed the charges had gone off, rendering the ship useless to her new owners for many months to come.
The carrier’s history and fate after Germany’s surrender was unclear for decades after the war. According to the terms of the Allied Tripartite Commission, a “Category C” ship (damaged or scuttled) should have been destroyed or sunk in deep water by August 15, 1946.
Instead, the Soviets decided to repair the damaged ship and it was refloated in March 1946 and enlisted in the Baltic Fleet as aircraft carrier Zeppelin. The last known photo of the carrier is dated April 7, 1947.
For many years, no other information about the ship’s fate was available. There was some speculation that it was very unlikely that the hull made it to Leningrad, as it was argued that the arrival of such a large and unusual vessel would have been noticed by Western intelligence services.
This seemed to imply that the hull was lost at sea during transfer to Leningrad. One account concluded that it struck a mine north of Rügen on August 15, 1947, but Rügen, west of Swinemünde, is not on the sailing route to Leningrad.
Further north in the Gulf of Finland, a heavily-mined area difficult for Western observers to monitor, seemed more likely.
After the opening of the Soviet archives, new light was shed on the mystery. Though some believed that the carrier had been towed to Leningrad after the war, in his book “Without wings, the story of Hitler’s aircraft carrier” Burke disputed this.
What is known is that the carrier was as “PB-101” (Floating Base Number 101) in February 3, 1947, until, on August 16, 1947, it was used as a practice target for Soviet ships and aircraft.
Allegedly the Soviets installed aerial bombs on the flight deck, in hangars and even inside the funnels (to simulate a load of combat munitions), and then dropped bombs from aircraft and fired shells and torpedoes at it.
This assault would both comply with the Tripartite mandate (albeit late) and provide the Soviets with experience in sinking an aircraft carrier.
By this point, the Cold War was underway, and the Soviets were well aware of the large numbers and central importance of aircraft carriers in the U.S. Navy, which in the event of an actual war between the Soviet Union and the United States would be targets of high strategic importance.
After being hit by 24 bombs and projectiles, the ship did not sink and had to be finished off by two torpedoes. The exact position of the wreck was unknown for decades.