IMPORTANT PREFACE

There are a couple interesting bits of information for this section:

1. The next three boats, U-233, U-234 and U-235 have a huge amount of information, so each will require several issues of our KTB Magazine;
 

2. There is absolutely NO TRUTH to a story put forth by a guy named Brooks in New England that U-233 was a very rare Type XI boat (none were ever built); that U-233 was in a gun battle with US Navy blimp K-14; and no truth to his story that this boat is secretly sunk in Casco Bay.  This was a 2,000 ton Type X-B mine-laying submarine, not the 3,600 ton Type XI submarine cruiser outfitted with four 5 inch guns as Brooks claims.  Also note that this boat was sunk about 1,000 miles off the American coast and half the crew was saved so there is no doubt as to which boat this was, what Type she was and where she was sunk.

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The Following is from Official US Navy Documents

TABLE OF CONTENTS

                                                                        Page

I.  INTRODUCTION                                         1

II.  DETAILS OF U-233                                    2            

III.  INFORMATION ON MINES                      7

IV.  CREW OF U-233                                     11

V.   EARLY HISTORY OF U-233                  13

VI.   FIRST & LAST PATROL OF U-233    15

VII.   SINKING OF U-233                               18

ANNEX: Crew List of U-233 & US Equivalents of German Naval Ranks and Ratings. 

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CHAPTER I.    INTRODUCTION

U-233, a 1600-ton minelaying U-Boat, commanded by Kapitänleutnant Hans Steen, was sunk on 5 July in position 42.16.5N-59.49W by USS BAKER and USS 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.

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 NR: 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.  

(b)  Two twin 20-mm. cannons on Platform I.

(c)   U-233’s original armament included  a 105mm 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 37mm   was added.

TORPEDO TUBES
 Two stern tubes only.
 

 TORPEDOES CARRIED
 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 07e, electric   torpedoes.

MINES
 66 carried (see Mine Information; Chapter III)

MINE SHAFTS
 Thirty fitted (all free flooding type). 

 Six in keel, through bow; three mines per shaft

 Twelve through starboard tanks; two 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.
 

SCHNORCHEL
(Extensible Diesel exhaust and air intake) Not fitted.

RADAR
 Not fitted. 

 RDB (Radar Decoy Balloons) Carried
 R.D.S.(Radar Decoy Spar Buoys) Not carried.

Sharkhunters EDITOR NOTE – The Radar Decoy Balloons referred to are the ‘Aphrodite’ balloons that are filled with hydrogen and floated aloft with tin foil strips to scramble radar.  It was a quantity of these balloons found aboard U-534 that ‘experts’ claimed were condoms!

  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. 

 (b)   Standard Telefunken receiving set    (Grossschiffempfanger).

U.K. GEAR   (VH/F)

Fitted but not used except during trials in conjunction with aircraft.

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.

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) & those on U-233 are as follows:

The mine (moored) is known as a ‘Druckunterschiedsmine’ (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 ‘Druckunterschiedsmine’ 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 ‘Druckunterschiedsmine’, and the effect of pressure in the following 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 if 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, become 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) off 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.  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 shaft s (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 complete 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.

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.

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, judging 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 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 unfortunate handling between the port of entry and the 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.
 

     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.
 

     Gartner, 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 aboard one 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.

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The story of U-233 will continue in KTB #190 next month.