Rainer Dierksen, U-176, killed shortly after his attacks on the Mambi and Nickeliner, 1943
Source: http://www.uboat.net/men/commanders/201.html, from U-Boats Museum, Cuxhaven
As Mambi and Nickeliner were sunk in the same convoy, same position and at the same time, their accounts should be read together. Since they were struck at the same time, Mambi will be covered first per alphabetical order.
The Mambi was a 1,983-ton Cuban tanker built in 1883 by Oswald, Mordount and Company, Southampton England. Like the Sama, the Mambi was originally built as a sailing vessel. She the oldest ship – at nearly 60 years of age – of those struck in the region. Her original name was Ladakh which was changed twenty years later to the Ninfa. In 1920 she was given her final name Mambi and in 1921 converted to a molasses tanker by her final owners, the Cuba Distilling Company, Incorporated, of New York. She was registered to Havana. Her dimensions were 269 feet in length, 40 feet wide, and 24 feet deep. An engine had been installed admidships aft.
On her final voyage the Mambi was loading molasses in Cuba, destined from and for the US. She left Port Everglades Florida for Havana in ballast. From Havana Mambi joined the steam ships Nickeliner, Connors and Mount Everest at 2:00 pm on the 10th of May for a passage to Nuevitas. She was in the relative safety of convoy NC-18, which was a coastal Cuban convoy designation.
Their escorts were the Cuban naval 83-foot patrol vessels (ex-US Navy) named CS 31, CS 32, and CS 33.
CS 31 was the lead vessel and it was under the command of Lieutenant Osirio Perez Soto. They stopped at Cayo Francis on the north coast at 2:30 on the 1th of Ma and left at 6:45 pm, arriving at Nuevitas at 3 pm on the 12th. From Nuevitas, also on the north coast, only the Nickeliner would proceed with the Mambi. Their next port was to be Nicarao, known as Antilla. Mambi’s first load port was to be Sagua de Tanamo, Cuba, presumably near Manzanillo.
On her final voyage Captain Ramon Alvarez Iturralde was responsible for 34 men on board the Mambi. Five of them were American Naval Armed Guard and the balance were the regular Cuban crew. The ship had left Nuevitas at twenty minutes past midnight on the 13th of May 1943 along with the one merchant ship and three escorts. She had water ballast in #3 and #4 tanks and the others were empty.
Her course was 112 degrees true east-southeast and her speed was eight knots, with the engine turning at 75 RPM. Mambi sailed to port of the Nickeliner, which was about 350 yards to her starboard. Mambi had lookouts on the stern gun, the bridge and the monkey island. Her degaussing coils, designed to detect and warn of enemy submarines, were on.
It was a clear and calm morning with no wind. Because the moon had set at 1:00 am the night was very dark. At 03:28 am local time the armed guard lookout, Charles S. Shepherd Jr. spotted the phosphorescent wake of a torpedo, from port to starboard, roughly 60 feet ahead of the Mambi. He also thought he saw an air bubble about 5,000 yards off the port beam, 270 degrees relative to her bow, which would have been the torpedo being released from U-176. The other torpedoes fired into the convoy struck the Nickeliner, the only ship in the convoy.
A torpedo struck the port side five seconds later from U-176 under Reiner Dierksen. Flooding followed immediately, and flames shot out of the starboard side, possibly gases from empty tanks exploding. As the engines, radio, steering gear and superstructure were all destroyed by the explosion, and the ship started sinking right away it was a case of every man for himself.
Mambi was broken in half by the torpedo and both ends of the ship sank within a minute, with both ends facing downwards and the stern and bow facing upwards. Though all of the lifeboats went down with the ship, two rafts fortuitously broke away from Mambi. Those fortunate enough to have slid, fallen or jumped off the doomed ship swam to those rafts. Out of 34 men survived, including Captain Iturralde, nine of his crew, and one of the American armed guard, Charles Samuel Shepherd, Jr..
The Cuban survivors included the Boson, Manuel Barcia rico, two Helmsmen, Andreas Suliva Subirat and Sebastian Dominguez Urdanivia, Deck Boy Rafael Gili Morales, two Oilers named Quintin Rodriguez and Miguel Reyes Bermudez, and Radio Operator Emilio G. Coya Alberich. These men were picked up by the Cuban escort vessels by 4:30 am and were subsequently landed back in Nuevitas.
The escorts combed the area for roughly four hours, finding the body of one of their crew-mates, Assistant Engineer Jesus Fernandez Rey. Thus, one crew was confirmed drowned and 22 others were missing. On shore six members of the Mambi crew required medical attention, three of them having broken bones.
The Cuban patrol boats escorting the convoy claimed they were taunted over the radio after the attack, and observed confusing light signals which they interpreted as indicating the presence of multiple submarines. CS 33 had a broken radio and steamed onwards, oblivious to the fact that all the ships in her convoy had been sunk. In the dry vernacular of the official report, “she was not seen again that night.”
The two other escorts turned to port and sought an echo contact. From then until they retrieved survivors from the Mambi their focus was on the Nickeliner and mysterious blinker lights and radio messages, which are covered in the section on the Nickeliner. Suffice to say that the taunts which came at the escorts from unidentified craft, were delivered in a voice described as “low and impressive, with possibly a slight Central American accent.” The voice said:
“Small launches escorting convoy, I have to tell you something important. Don’t take any shit. You are too little to get me. Get away from me with that shit.”
The escorts and their colleagues in the Cuban navy would achieve swift revenge – two days later Cuban patrol boats in coordination with American air support were able to depth charge and destroy U-176 between Cay Sal Bank Bahamas and Cuba. There were no survivors amongst Dierksen and his crew and no injuries to the Cuban defenders or the ships in their convoy.