'Hai' (i) was a U-boat wolfpack operation in the Atlantic against the OS.33 convoy (3/21 July 1942).

The wolfpack comprised U-116, U-136, U-201, U-572, U-582 and U-752, and for the loss of Kapitänleutnant Heinrich Zimmermann’s U-136 sank eight ships (61,125 tons) and damaged one 7,093-ton ship.

At 00.36 on 6 July, after chasing her for five hours, Kapitänleutnant Adalbert Schnee’s U-201 torpedoed the unescorted 14,443-ton British Blue Star Line passenger ship Avila Star some 90 miles (145 km) to the east of San Miguel in the Azores islands group. At 00.54 the boat fired another torpedo, which failed to explode, but another, fired four minutes later, did detonate and the ship capsized and sank one hour later, taking with her 67 merchant seamen and 17 passengers. The remaining 112 persons (93 crewmen, six gunners and 13 passengers) were later rescued.

As the wolfpack continued to move farther to the south, the tanker U-116 located the OS.33 convoy of 41 ships after a six-ship group of the convoy had been detached for ports in South America. A combined attack by U-116 and U-201 followed, and at 00.22 on 12 July, the straggling 7,093-ton British Cortona was hit by a torpedo fired by Korvettenkapitän Werner von Schmitt’s U-116, and three minutes later by another from Schnee’s U-201. Another torpedo from U-201 struck amidships at 00.41 and caused the ship to sink after about an hour. Of the crew, 29 men and two gunners were lost, while the master, 18 crew and four gunners were picked up in their lifeboat 10 days later by the British destroyer Pathfinder.

At 01.47 on 12 July the 8,826-ton British Port Hunter took a hit from a torpedo fired by Korvettenkapitän Werner Schulte’s U-582 and, with a cargo including ammunition and depth charges, suffered several internal explosions and sank within two minutes. The master, 68 crew, 14 gunners and five passengers were lost, the only survivors being three crewmen who had been sleeping on deck and were blown into the water to survive by clinging to wreckage until rescued by the British frigate Rother after seven hours in the sea.

U-136 was sunk by the frigate Spey, sloop Pelican and Free French destroyer Léopard.

At 09.45 on 12 July, the straggling 4,284-ton British Shaftesbury was hit by two torpedoes from U-116 and sank in 15 minutes. There were no losses among the crew, although the master was taken prisoner by the U-boat. The second officer and 22 crew were picked up on 23 July by the Tuscan Star, while the chief officer and 20 other survivors made landfall at Villa Cisneros, Spanish Sahara.

At 04.13 on 12 July, the straggling 5,242-ton British Siris was hit by a torpedo from U-201 and sank at 06.26 after the U-boat had surfaced and engaged the damaged ship with 100 rounds from its deck gun. In the attack a member of the crew and two gunners were killed, while the master, 46 crew and five gunners abandoned ship, and were picked up 10 days later by the British corvette Jonquil.

At 02.21 on 13 July, the straggling 6,723-ton British Sithonia was torpedoed and sunk by U-201, Seven of the crew were killed, but the master and 20 men made landfall at Timiris, French West Africa, after 18 days at sea, and were interned by the Vichy French, while the chief officer and 24 men were picked up by a Spanish fishing vessel after 14 days.

U-201 struck again at 01.46 on 15 July, sinking the unescorted 6,990-ton British tanker British Yeoman with a single torpedo after chasing her for about 14 hours. The tanker, loaded with 9,700 tons of fuel oil, immediately caught fire. During the morning of the following day the U-boat returned to the scene of the attack and found the stern of the ship still floating, and sank it with 61 rounds from its deck gun. Only 10 of the crew of 53 survived.

At 03.30 on 15 July U-582 torpedoed and sank the 7,524-ton British Empire Attendant to the south of the Canary islands group. There were no survivors of the 59-man crew.

After its operation against the OS.33 convoy, the 'Hai' (i) wolfpack moved in line abreast toward the area of Freetown, Sierra Leone, and in the period up to 23 August its boats made more sinkings. U-201 sank the anti-submarine trawler Laertes; U-572 sank the 5,281-ton Dutch Delfshaven; U-752 sank the 5,254-ton British Garmula, 4,003-ton Norwegian Leikanger, 6,047-ton Dutch Mendanau and 6,347-ton US Cripple Creek; and U-582 sank the 7,943-ton US Honolulan and 6,801-ton US Stella Lykes.