| Op-16-Z | ||
Copy No. 29 of 49. |
||
NAVY DEPARTMENT |
||
OFFICE OF THE CHIEF OF NAVAL OPERATIONS |
||
WASHINGTON |
||
FINAL REPORT – G/SERIAL 45 |
||
REPORT ON THE |
||
INTERROGATION OF SURVIVORS FROM U-233 |
||
SUNK 5 JULY 1944 |
||
| DISTRIBUTION: |
||
| BAD | ||
| BUORD | ||
| BUSHIPS | ||
| BUSHIPS (Code 515) | ||
| BUSHIPS (Code 815) | ||
| COMINCH (F-21) | ||
| COMINCH (4253) | ||
| COMINCH (F-45) | ||
| COMINCH (FX-40) | ||
| COMINCH (FX-43) | ||
| COMNAVEU | ||
| DNI (Ottawa) | ||
| G-2 (Col. Sweet) | ||
| Op-16-1 via Op-16-1-F | ||
| Op-16-FA-4 | ||
| Op-16-P | ||
| Op-16-W | ||
| Op-20-G | ||
| Op-23-C | ||
| SONRD | ||
| Lt. Cdr. V. R. Taylor | ||
| C.O., Naval Unit, Tracy, Calif. | ||
| Lt. J. I. Eiband (COMNAVNAW, CSDIC, AFHQ) | ||
| Lt. S. R. Hatton (COMNAVNAW, CSDIC, AFHQ) | ||
| Lt. J. T. Rugh, Jr. (JICA/ME) | ||
| COMASDEVLANT | ||
| CINCLANT | ||
| COM8THFLEET | ||
| COM4THFLEET | ||
| Op-30 | ||
| 21 September 1944 | ||
 |
 |
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
CHAPTER I. INTRODUCTION |
||
| U-233, a 1600-ton minelaying U-boat, commanded by Kapitänleutnant Hans Steen, was sunk on 5 July in position 42.16.5 N. – 59.49 W. by U.S.S. BAKER and THOMAS operating with Task Group 22.10. U-233 was on her first patrol when sunk and was en route for Halifax where she was to carry out a minelaying operation. | ||
| Twenty-nine men, including both watch officers and a midshipman, were rescued and brought to the United States. U-233’s commander was also rescued, badly wounded, and died some hours later on board one of the rescuing vessels. | ||
| The brief career of U-233 offered little of interest. The main item of interest in this report is a description of a new type of mine (pressure differential mine) carried by U-233 and said to be carried by other minelaying U-boats with shafts. | ||
- 1 - |
||
|
|
|
CHAPTER II. DETAILS OF U-233 |
||
| TONNAGE | ||
| 1600-tons. | ||
| TYPE | ||
| X-B (minelayer and supply boat). | ||
| BUILDING YARD | ||
| Germania, Kiel. | ||
| COMMISSIONED | ||
| 22 September 1943. | ||
| FLOTILLA | ||
| Fifth at Kiel. | ||
| FIELD POST NUMBER | ||
| M-54276. | ||
| INSIGNIA | ||
| Chimney Sweep (worn on crew’s caps only). | ||
| MAXIMUM DEPTH ATTAINED | ||
| 120 meters. Prisoners stated depth gauge scale marked to 125 meters. | ||
| GUNS | ||
| (a) Automatic 37-mm. gun on Platform II; one reserve barrel carried. | ||
- 2 - |
||
|
|
|
| (b) Two twin 20-mm. cannons on Platform I. | ||
| (c) U-233’s original armament included a 105-mm. gun forward which was removed during the final overhaul at Kiel during which time the 37-mm. was added. | ||
| PRESSURE PROOF AMMUNITION CONTAINERS | ||
| (a) Three for 37-mm. ammunition abaft 37-mm. gun on Platform II. | ||
| (b) Four for 20-mm. cannons on Platform I; two for each twin mounting. | ||
| TORPEDO TUBES | ||
| Two stern tubes only. | ||
| Seven carried. | ||
| DISPOSITION AND TYPE OF TORPEDOES | ||
| Stern tubes – two T-5 torpedoes (on WS setting). | ||
| On floor plates in after compartment – two T-5 torpedoes (on WS setting). | ||
| Beneath floor plates – three regular G7e, electric torpedoes. | ||
| MINES | ||
| Sixty-six carried (see Mine Information – Chapter III). | ||
| MINE SHAFTS | ||
| Thirty fitted (all free flooding type). | ||
- 3 - |
||
|
|
|
| Six in keel line, through bow compartment; three mines per shaft. | ||
| Twelve through starboard tanks; two mines per shaft. | ||
| Twelve through port tanks; two mines per shaft. | ||
| DIESELS | ||
| Two 9-cylinder G.W. Diesels with Kapsel type superchargers. | ||
| DIESEL SPEEDS | ||
| Telegraph Speeds R.P.M. | ||
| K.F. (Dead Slow) 190 | ||
| 3XA.K. (Emergency Speed) 485 | ||
| MAXIMUM SPEED | ||
| About fifteen knots. | ||
| FUEL OIL CAPACITY | ||
| 400 cubic meters. | ||
| MOTORS/GENERATORS | ||
| A.E.G. | ||
| SWITCHBOARD | ||
| A.E.G. | ||
| SCHNORCHEL (Extensible Diesel exhaust and air intake) | ||
| Not fitted. | ||
| RADAR | ||
| Not fitted. | ||
- 4 - |
||
|
|
|
| R.D.B. (Radar Decoy Balloons) | ||
| Carried. | ||
| R.D.S. (Radar Decoy Spar Buoys) | ||
| Not carried. | ||
| G.S.R. (German Search Receiver) | ||
| (a) Naxos. | ||
| (b) Wanz G-2. | ||
| (c) Borkum. | ||
| It was stated that alarms on Naxos contacts were frequent, but that none were received on Wanz G-2 or Borkum. | ||
| G.S.R. AERIALS | ||
| (a) Naxos “Fliege” aerial. | ||
| (b) Ordinary basket-type dipole aerial. | ||
| D/F GEAR | ||
| Standard long-wave Lorenz D/F set. | ||
| TRANSMITTERS | ||
| (a) 200-watt Telefunken short-wave transmitter. | ||
| (b) 150-watt Telefunken long-wave transmitter. | ||
| (c) 40-watt Telefunken emergency transmitter. | ||
| (d) 200-watt Telefunken F.K.W. (Fernverkehrkurzwellensender), H/F transmitter. Not fitted. | ||
| RECEIVERS | ||
| (a) Telefunken all-wave receiver. | ||
- 5 - |
||
|
|
|
| (b) Standard Telefunken receiving set (Grossschiffempfänger). | ||
| HYDROPHONES | ||
| “Atlas” G.H.G. fitted. | ||
| S.B.T. (Submarine Bubble Target) | ||
| Not fitted. | ||
| D.C.P. (Depth Charge Plotter) | ||
| Not fitted. | ||
| COLOR | ||
| Dark gray. | ||
| RUBBER RAFTS | ||
| One for each man. | ||
| Two or three which held four to five men. | ||
- 6 - |
||
|
|
|
CHAPTER III. INFORMATION ON MINES |
||
| The following information was, to a large degree, obtained from one well informed prisoner. It is believed that, in as far as the prisoner’s knowledge went, this information is reliable. But it is emphasized that he was not informed on all points of interest. | ||
| PRESSURE DIFFERENTIAL MINE | ||
| According to various prisoners, the mines on U-233 appear to have been the same as the GO mines carried by U-118. According to one prisoner, however, the difference between the GO (he did not know the German designation) and those on U-233 are as follows: | ||
| The mine (moored) is known as a “Drückunterschiedsmine” (pressure differential mine), a term which describes the mine’s ability to maintain a pre-set depth of four to six meters below the water surface, regardless of tide conditions. A prisoner insists that the term “Drückunterschiedsmine”, which he heard at the Sperrversuchs Kommando (Experimental Mine Command) at Kiel in April 1944, applies to the mines carried by U-233 (and to be carried by other minelaying U-boats with shafts), and that the term applies only to a depth-keeping arrangement. | ||
| DEPTH SETTING | ||
| The depth at which the mine case was to be moored was set (at the “Sperrzeugamt” mine depot) in the drum located in the upper left hand corner of the anchor. The prisoner explained the expression “Drückunterschiedsmine”, and the effect of pressure in the following | ||
- 7 - |
||
|
|
|
| way: in depths of sixty meters the case becomes moored at 54-56 meters; changing tide conditions cause a change in water pressure, which change acts on the regulator in the anchor, causing the case to rise or fall so as to maintain a constant depth between four and six meters below the surface. (The prisoner had never heard of a mine which operates like OYSTER. He did not know whether the mine on U-233 could remain married to the anchor and thus become a ground mine; and he did not know whether such a mine would, if sunk by rifle fire or by a small scuttling charge, became a ground mine). | ||
| ANCHOR DEPTH | ||
| The mines were primarily for harbor-laying. Anchor depth was said to be 200 meters. The depth of water in which U-233 laid practice mines (of same type) off Hela, was said to have been 80 meters. The greatest depth reached by U-233 was 120 meters, but it was stated that diving depth was not restricted by presence of mines on board. | ||
| OTHER DETAILS | ||
| The mines on U-233 were moored magnetic (bi-Polar) with an induction coil – NO NEEDLE. The number of actuations required to fire are not known. | ||
| U-233 laid 132 similar mines (although painted white) of Hela within three days. They were all laid at periscope depth at about five knots. One mine was laid every thirty seconds. | ||
| The charge of the mine was believed to be three hundred kilograms. The mine was fitted with a twenty-four hour delay arriving clock, but the existence of other clockwork was not known. | ||
- 8 - |
||
|
|
|
| The spacing between mines when laid was to be 500 meters. | ||
| ORDER MINES LAID | ||
| The order in which mines were laid was as follows: | ||
| Forward Shafts (three mines in each of six); lower mines of first three shafts to be laid first, followed by middle mines in same three shafts, after which top mines in same shafts laid. The same procedure for the three remaining shafts. | ||
| Starboard and port shafts (two mines in each of twelve starboard and twelve port shafts): | ||
| Mine 19 (lower mine of starboard shaft); | ||
| Mine 20 (lower mine of port shaft); | ||
| Mine 21 (upper mine of starboard shaft); | ||
| Mine 22 (upper mine of port shaft); | ||
| and so on until operation completed with laying of mine 66 (upper mine, port shaft). | ||
| MISCELLANEOUS | ||
| It was believed that these mines also may be laid by surface craft. | ||
| The mines are primarily to be laid off harbors, about four to five nautical miles from the harbors themselves. | ||
| U-233 had planned to spend one and one half days off Halifax to lay her mines. | ||
| No protuberances and no holes were seen on the mine cases. Also no rubber was seen on the case, except a rubber gasket under the top cover plate. | ||
- 9 - |
||
|
|
|
| U-233 was demagnetized at Kiel, eight to ten days before she sailed. There were no mines on board during the wiping process. The mines were loaded six days before U-233 sailed. | ||
| It was stated that the mine case was made of steel. | ||
- 10 - |
||
|
|
|
Click this text to view a diagram of a Pressure Mine
CHAPTER IV. CREW OF U-233 |
||
| GENERAL | ||
| U-233 carried a total complement of 60 officers and men: the captain, two watch officers. An engineer officer, a doctor, a midshipman under training who also acted as third watch officer, and 54 men. | ||
| The crew, judged from the 29 survivors, was a poor one. Most of the men were totally lacking in previous U-boat experience and a large number had never been to sea before. As a whole they gave the impression of being in the dregs of the reserve pools in Germany and shore stations on the Baltic, with a very small sprinkling of experienced petty officers to stiffen the whole. | ||
| Due to the unfortunate handling between the port of entry and interrogation center the crew, in addition, was extremely secure and presented a very difficult problem to interrogators. This security consciousness was undoubtedly enhanced by the character of U-233’s mission and the fact that so many of the crew had spent the war in Germany under the full influence of propaganda and without the revealing experience of life at the front. | ||
| OFFICERS | ||
| Steen was popular with his crew and considered to be an efficient officer. He belonged to the April 1937 Naval Term, but little is known of his career. Prior to taking over U-233 he was first watch officer under Neumann on U-117, a 1600-ton supply boat. | ||
- 11 - |
||
|
|
|
| Betzin, the first watch officer, was formerly in the merchant marine. To interrogators he was sly and vain, though apparently popular enough with the crew. | ||
| Gärtner, the second watch officer, was nondescript and secure. Some of the men thought he was too young for his responsibilities. He belonged to the May 1941 Naval Term. | ||
| Huar, the midshipman, was an unpleasant little Nazi who distinguished himself on board on of the rescuing vessels by posing as one of the men until he got tired of being treated like one. | ||
| Nothing is known of Bartling, the engineer officer, except that he belonged to the October 1937 Naval Term, or of Moeller, the doctor, except that he was said to have been born in Russia. | ||
| MEN | ||
| Typical of the motley character of the crew was the chief boatswain, a man 42 years old who had first enlisted in 1921 and who, with the exception of a brief period on a schoolboat, had no previous U-boat experience. | ||
| The crew as a whole, besides their inexperience, showed little interest in the U-boat arm, knew little about it and cared less. If they could be taken as typical of the crews now manning the newer German U-boats, the prospect would be encouraging indeed. But past experience has shown that no general conclusions can be accurately drawn from the experience of one crew. | ||
- 12 - |
||
|
|
|
CHAPTER V. EARLY HISTORY OF U-233 |
||
| COMMISSIONING | ||
| U-233 was commissioned at Germania Werft, Kiel, on 22 September 1943. | ||
| TRIALS AND EXERCISES | ||
| After her acceptance trials, which lasted until about the end of October, U-233 proceeded to the Baltic for the usual trials. During tactical exercises at Hela in November/December 1943, U-233 on two occasions laid a full complement of 66 mines. The mines were loaded at Hela and both exercises were said to have been a complete success. It was stated that on neither occasion did any of the mines explode prematurely. The only untoward incident during tactical exercises was when U-233 rammed her bow into a mudbank at a depth of twenty-five to thirty meters. Little damage was done, but extrication proved extremely difficult and the crew were much relieved to see the surface again. Torpedo firing trials were carried out at Gotenhafen and the crew went on Xmas leave in two watches from there. | ||
| FINAL OVERHAUL | ||
| U-233 returned to Kiel for her final overhaul about the beginning of February 1944. During this period the conning tower was rebuilt, the 37 mm. installed on Platform II, and the 105 mm. forward gun removed. U-233 also was fitted with Wanz G-2 GSR at this time. | ||
- 13 - |
||
|
|
|
| FLAK COURSE AND FIRING EXERCISES | ||
| About 1 April U-233 went to Swinemuende where members of the crew took a week’s “flak” course. At the conclusion of this a short trip was made to Hela. Here the U-boat made a few extra trial runs. Some prisoners thought this was for the benefit of the few new personnel who had joined the boat when she was in Kiel. U-233 then returned to Swinemuende for a short week’s “flak” firing exercises prior to returning to Kiel to make ready for her first patrol. | ||
| U-233 AS A SUPPLY BOAT | ||
| Prisoners insisted that, during her trial period, U-233 at no time practiced refueling or any other special duties of a supply boat. Some prisoners explained this by the fact that Kapitänleutnant STEEN had formerly been Neumann’s executive officer on U-117 (a 1600-ton supply boat) and therefore was fully familiar with those details. Others thought that U-233 was not to be used as a supply boat at all, at not least until after her first patrol, and that perhaps they would receive instructions in these duties at Bordeaux. Prior to setting out on her first patrol U-233 apparently embarked a full supply (400 cubic meters) of fuel oil, but prisoners stated that they had little in the way of spare parts or supplies, except what might be needed for a normal length patrol. One prisoner stated that no spare parts for other types of U-boats were carried. | ||
- 14 - |
||
|
|
|
CHAPTER VI. FIRST AND LAST PATROL OF U-233 |
||
| KIEL TO KRISTIANSAND | ||
| U-233 left Kiel on her first patrol at 0800, 27 May 1944. She was accompanied by four or five unidentified 500-ton U-boats, but they parted company soon after leaving Kiel. U-233 entered Kristiansand at 0700, 29 May. | ||
| During their short stay members of the crew saw an unidentified 500-ton U-boat, whose commander was said to be an Oberleutnant, which was due to leave for Narvik shortly. Two or three of the U-boats which had left Kiel with U-233 also reappeared at Kristiansand. | ||
| DEPARTURE FROM KRISTIANSAND | ||
| U-233 left Kristiansand at 1400, 29 May in company with the above mentioned U-boats. They parted company shortly afterwards and were not seen again. | ||
| AIRCRAFT WARNINGS AND ATTACKS | ||
| (O.N.I. Note: While all the following events have been confirmed by interrogation, some of the dates and times were obtained from a captured diary and are presumed to be reasonably accurate.) Soon after leaving Kristiansand U-233 made a deep-diving test and then proceeded submerged. Difficulty was experienced in pumping out the bilges and it had almost been decided to return to Kristiansand when the engineer officer discovered a small chisel in the pump manifold. Some crew members suspected sabotage. | ||
- 15 - |
||
|
|
|
| Some time during 30 May twelve very distant depth-charge explosions were heard, but they were not believed directed at them. On 31 May a number of aircraft were actually sighted. U-233, however, apparently remained undetected. | ||
| At 2400 on 1 June U-233 surfaced to recharge batteries and replenish air bottles. At 0100 she was force to dive by the presence of aircraft and did not surface again until 1200, when prisoners estimated they were off the Shetlands. Shortly thereafter U-233 was attacked by four motored aircraft thought by prisoners to have been a Sunderland. She fired on the attacking plane and, despite intermittent jamming on the part of the 37-mm. gun, hits are believed to have been scored. The plane dropped five bombs and one fell only 25 to 30 meters from the U-boat; the others were said to have been less accurate. No damage, however, was caused. The plane flew off and some twenty minutes later U-233 was forced to dive after sighting two more Sunderlands. | ||
| In the early morning of 3 June U-233, her batteries low and her air foul, surfaced again. No sooner had the bridge watch taken up their stations, when aircraft again forced the boat to crash-dive. Depth-charges were dropped when the boat was at 30 meters, but U-233 again escaped damage. The situation in the boat was now serious and it was absolutely necessary that she surface. An alteration of course was made and U-233 surfaced shortly thereafter. This time she was fortunate enough to find the coast clear and was able to | ||
- 16 - |
||
|
|
|
| proceed with her recharging unhindered. | ||
| ENCOUNTER WITH A DESTROYER | ||
| About the middle of the patrol U-233 sighted a destroyer at some distance. Steen began to maneuver into an attacking position, when suddenly the destroyer moved off at high speed. Prisoners believed that she had become aware of the U-boat’s proximity and had decided not to risk an encounter. | ||
| FAILURE OF 37-MM. GUN | ||
| About two weeks after the second aircraft attack, it was decided to fire a few test rounds from the 37-mm. Five shells were to be fired, but the first one exploded in the breech, completely wrecking it, but miraculously wounding nobody. The gun was rendered useless for the balance of the patrol and was from then on referred to as the “old broom” (“olle Besen”). | ||
| PASSAGE TOWARDS HALIFAX | ||
| U-233’s mission was to lay mines off Halifax, and she proceeded at slow speed towards that goal with the intention of arriving after the full moon. About twenty hours of each twenty-four were spent submerged and there appears to have been no fixed time adhered to for surfacing and recharging. All prisoners insisted that they knew of no plans for acting as a supply boat after the minelaying operation, and it was presumed, though not definitely known, that they were to put into Bordeaux at the conclusion of the patrol. | ||
- 17 - |
||
|
|
|
CHAPTER VII. SINKING OF U-233 |
||
| U-BOAT SURPRISED AT SHALLOW DEPTH | ||
| U-233 was proceeding submerged at 30-50 meters in the early evening of 5 July. The U-boat had to come to this level from her usual depth of 60-80 meters to facilitate torpedo servicing in the after compartment and possibly to attempt repairs on a damaged tube. (O.N.I. Note: As not a single man escaped from the after torpedo room compartment, the Diesel or electric motor room, it has not been possible to establish the sequence of events in that part of the boat.) Suddenly a loud whining sound was heard in the boat, followed shortly afterwards by screw noises. Almost immediately afterwards depth-charges exploded all around the U-boat. (O.N.I. Note: At 1911, 5 July USS BAKER, after gaining sound contact, dropped a full pattern of depth-charges.) The U-boat was severely shaken up, lights went off the board and loose gear flew all over the boat. U-233 descended rapidly and out of control to about 120 meters. | ||
| WATER ENTRY AFT | ||
| At 120 meters a water entry aft developed to such a degree that she became stern heavy. It was rumored among survivors, although not confirmed by an eye witness, that a torpedo withdrawn from one of the tubes in the after compartment and which was on the loading rails suddenly slid into the tube with such violence that is disemboweled a torpedoman who happened to be in the way. Survivors conjectured that | ||
- 18 - |
||
|
|
|
| SECOND DEPTH CHARGE ATTACK | ||
| The U-boat continued to sink by the stern at an alarming angle, rapidly getting out of control. Shortly after this a second pattern of depth-charges exploded around the boat without, however, causing much further damage. (O.N.I. Note: At 1920 BAKER dropped a second pattern of depth-charges set at shallow.) Shortly thereafter the order was given to blow tanks and the U-boat slowly came to the surface, regaining an even keel as she did so. The order to abandon ship was given immediately and the engineer officer was the first through the conning tower hatch. The fire from the attacking destroyers was by this time heavy and accurate and the engineer was hit and slumped down in the conning tower. Several other crew members who tried to leave the boat by this means were also killed or badly wounded and the conning tower became a shambles. The 30 survivors who were ultimately rescued all escaped from the boat by the forward hatch. | ||
| U-233 RAMMED AND SUNK | ||
| (O.N.I. Note: At 1930 Commander Escort Division 48 ordered THOMAS to ram the submarine. At 1946 THOMAS…..rammed the submarine…..abaft the conning tower…..U-233 then sank beneath THOMAS.) | ||
| With the exception of those trapped in the after part of the boat, the whole crew had abandoned ship before the U-boat was rammed. | ||
- 19 - |
||
|
|
|
| prisoners were emphatic that no attempt was made to man the guns, stating that the fire to which they were subjected made this impossible. No signal was sent to Control advising them of U-233’s sinking. | ||
| Thirty survivors were picked up, 10 by BAKER and 20 by THOMAS. Kapitänleutnant Steen, who died later, was buried at sea. | ||
- 20 - |
||
|
|
|
CHAPTER XIII. OTHER U-BOATS |
||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||
- 21 - |
||||||||||||||||||||||||||||
|
|
|
U-BOATS IDENTIFIED BY COMMANDING OFFICERS |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
- 22 - |
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
|
|