In July 2012, U.S. divers use sonar to detect a German submarine.

History of the wreck
After just under 6.5 months of construction at the Deutsche Werft AG, Hamburg-Finkenwerder the German submarine U-550 was launched on 12.05.1943 and was put into service on 28.07.1943. The Type IX C 40 submarine had 2 diesel and 2 electric engines in its hull (76.7 x 6.76 x 4.70 m). The diesel engines produced 4400 hp with a maximum speed of 18.2 knots while the electric motors with 1000 hp were allowed to reach only 7.7 kn.

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After entering service, the U-550 operated as a training boat under Commander Klaus Hänert from Stettin. Under the command of Klaus Hänert, the U-550 was assigned to the 10th U-flotilla at Lorient as a frontline boat on 01 February 1944. Its task was to intercept convoys in the operational area of the Atlantic off the coast of New York between Long Island and Nantucket.

Here now is the sinking report of Commander Klaus Hänert:

The boat is on 16.04.1944 in the area of operation of

New York on the coast between Long Island and Nantucket. At night over water recharging the batteries. At the same time the light glow of the city of New York in the sky to see. In the morning, about two hours after dawn, sounding to the west. The boat goes to periscope depth. To starboard and port, destroyers came into view at times, recognizable as far as the bridge. Ahead on the right is an aircraft carrier, behind it a convoy in broad but close formation, consisting of about 12 to 15 tankers.

At first, the attack course is set for the carrier, but then operations are conducted on the escort. At periscope depth, the destroyer protection is penetrated unnoticed. The intention was to fire a FAT 3 fan at one of the tankers. But its own speed was too high, so U 550 got caught in the middle of the escort. Fast ahead on a tanker, released a torpedo. No sooner was the torpedo out of the tube than the chief engineer reported “Boat can’t be held”. “Then down LI boat must not come out”, came immediately my order. The water depth here was about 80 to 90 meters. My intention was to get into the deeper water. Then after about 30 to 40 seconds, there was a detonation. The torpedo had hit. Meanwhile, the boat got grounded at about 70 meters. U 550 was stuck in the mud of the seabed and could only be freed by hard measures. In the meantime, the convoy overran the boat, which was stuck on the bottom. Then searching destroyers were noticed in the group sounding, in the boat everything was turned off. Above, three standing bearings were detected. So the boat was spotted. Carefully, an attempt was made to detach the boat from the bottom. At the same moment, well-laid depth charges detonated above the stern. While the damage was being repaired, the second series of depth charges took place. Heavy water and fuel oil burst in the diesel and stern compartments. The damage was beyond repair. Immediately I gave the order to blow and disembark the crew. Shortly thereafter, the chief engineer reported, “Boat is out!” Already when opening the turret hatch, the shelling of three destroyers begins, which lay in a circle around the boat, at a distance of about 50 to 150 meters, I myself fell down the turret ladder again with wounds on the head, arms, and legs. I could no longer see anything with my right eye. The top rung under the tower hatch had been shot away. Further shelling made the turret a sieve. Seaman No. 1 and the combat helmsman had fallen. The boat was sinking slowly, but getting out of the turret was impossible because of the shelling. “Under all hatches clear to bail out!” “Unhook all tubes by hand,” followed my orders. But only one T-5 Wren torpedo exited tube II. Torpedo tubes V and VI were down. After about 15 minutes of strafing, the fire ceased for reasons unknown. About 40 men led by the I Officer of the Watch disembarked as ordered and swam toward the nearest destroyer. The water temperature was about 5 degrees Celsius. But suddenly the destroyer turned away without picking up the men. None of these crewmen were rescued. After another 10 to 15 minutes, the U.S. destroyer “USS Joyce” drifted close to U 550, coming from port forward, and picked up the rest of the crew. Meanwhile, the lead engineer reported that the boat had been cleared except for the two dead in the turret. U 550 was now sinking rapidly. No vents were being operated. The lead engineer reported off the boat, then I also jumped into the water. Before I was picked up by the destroyer, the boat had sunk over the sternpost, according to the observation of the Chief Engineer, who was already aboard “USS Joyce.” There was no excuse for the failure to rescue most of the crew. The Americans’ explanation was that the destroyer commander had gone berserk. He suspected a second submarine, which was probably due to our own T-5 that missed, because they themselves rescued only 15 men from the 45 crew, of the tanker we had sunk earlier. On board, the destroyer in twelve days in escort crossed the Atlantic. The treatment on board was correct.

US reports said the U-550 was sunk by a ramming blow from the US destroyer “USS Gandy”. However, this did not coincide with the sinking report of the commander of the U-550.

After 11 months in American captivity, the Kammeraden returned home.

Diving into the wreck
The wreck of the U-550 was discovered about 100 km south of the island of Nantucket.  Since the U-550 must be between 70 and 100 meters deep, it is accessible to tec divers. However, whether it will be cleared for diving will be up to the U.S. government to decide.

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Recommendation: Trimix

Sources and links about the wreck

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U-550 at Süddeutsche Zeitung (German)

U-550 at Lexikon der Wehrmacht (German)

U-550 at U-Boot-Archiv (german)

U-550 at Wikipedia (German)

U-550 as a photo series at Spiegel (German)

U-550 at Uboat.net (English)

List of German submarines at AHA-Express

List of German submarines at U-Bootarchiv.de

List of German submarines at All2know.com

WWWII submarine losses by Robikush (private)

Wreck type:Submarine IX C 40Year built:1943
min. Dive depth:75 mLoss date:16.04.1944
max. dive depth:75 mLoss reason:Artillery after depth charges
GPS data:40. 09′ NLocation Country:USA
 69.44′ WLocation Region:Island of Nantucket, 100km south
Dive Site: Personally dived?No