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File: A9-16(3) (10/Hn)
29 August 1945.
From: Chief, U.S. Naval Technical Mission in Europe.
To: Chief of Naval Operations (OP-16-PT)
Subject: U.S. Naval Technical Mission in Europe Technical Report No. 222-45, Loss of the German Battleship Tirpitz on 12 November 1945 – Forwarding of.
1. Enclosures (A), (B) and (C) are forwarded herewith.
2. CNO (OP-16-PT) is requested to make complete additional copies of this report for such other agencies as may be interested.
CNO (OP-16-PT) Copy Nos. 1 - 2
TABLE OF CONTENTS
(b) Admiralty Battle Summary No. 27 (1945) CB-3081(20), "Naval A/C Attack on TIRPITZ", (Operation “Tungsten”) on 3 April, 1944.
(c) British Air Ministry Operational Research Section (Bomber Command) Report S.218 “Results of Attacks with 12,000 M.C. (“Tallboy”) Bombs," dated 2 May 1945.
(d) Official German Reports Concerning Loss of TIRPITZ (included with translations as Appendix "A”).
L.B.P. - 790 feet
L.O.A. - 821.5 feet
Beam (moulded) - 118.0 feet
Drafts - 29.0 feet forward; 29.0 feet aft
Displacement - 42,000 tons
GM - 12.0 feet
This report on the loss of the German battleship "Tirpitz” is based primarily on the references. Supplementary information was obtained by an interrogation of Fregatten Kapitan (Ing.) [Alfred] Eichler, who had been through earlier attacks on “Tirpitz” as Chief Engineer. Although not present at the time of the sinking, Eichler, had talked with survivors concerning the damage control aspects of the attack.
"Tirpitz" had been subjected to a number of air and submarine attacks which resulted in minor damage only (references (a), (b), and (c)). During a raid on 3 April 1944, she was struck by a total of 16 bombs, ranging 500-pound general purpose bombs with instantaneous fuses to 1600-pound armor piercing with 0.8 seconds delay in the fuze. There was extensive non-vital damage to portions of the superstructure and other spaces in the upper watertight part of the ship, but only a dud pierced the armoured deck. During an attack on 15 September, 1944, the following damage was incurred: (1) the forward 100 feet of the bow was destroyed and the bottom shell plating ruptured or buckled for about 50 feet further aft: (2) the bow was flooded from the forward end for about 120 feet below the upper platform and for about 80 feet on the upper platform. Furthermore, the starboard propeller shaft tunnel and shell plating in the immediate vicinity were ruptured during a midget submarine attack causing the flooding of several small spaces low in the ship at the stern. None of this underwater damage at the bow and stern was repaired.
On the morning of 12 November, 1944, “Tirpitz” was lying at anchor in Tromsoe Fiord, located in the northern part of Norway. The fuel and fresh water on board amounted to only about 3,000 tons, approximately 30 percent of full load. The vessel was without trim, but had a list of one degree to port. Stern and bow anchors were out to deep her from swinging into unfavorable defensive positions. A torpedo net enclosed the ship as protection against submarines and other types of sneak craft. An air raid watch had been stationed at daybreak. The weather was fair, skies clear and visibility excellent. The wind was from SSW force 1.
0800 - The first warning was received concerning single bombers in the vicinity of Bodoe. "Tirpitz” was connected immediately to the main air raid warning station at Tromsoe.
Note: All times may be slightly in error.
0815 - An additional warning was received that 3 Lancasters with Mosquito fighter escort had been sighted at 0737 flying in on an easterly course. More Lancasters were reported approaching on a north-easterly course. Fighter protection was requested by "Tirpitz” but no acknowledgment was received.
0854 - An air raid alarm was sounded for the ship and the city of Tromsoe. It was apparently at this time that battle stations were manned, closures set and the vessel made ready for action. One boiler in the starboard forward fireroom (Kesselraum Stbd. v.) furnished steam to the turbo generator in generator room No. 3 (E. Masch. R3). Steam for the turbo generator in generator room No. 4 (E. Masch. R4) probably came from a boiler in the after port fireroom (Kesselraum Bb.h.). The battle electrical load was split between the two generators in accordance with established procedure.
0915 - A formation of about 18 British aircraft was sighted approaching at an estimated range of 75 miles. At a range of about 55 miles these planes headed directly toward “Tirpitz”. Shortly thereafter a second formation of about 12 planes was sighted by "Tirpltz". The altitude of both flights was 12,500 to 16,500 feet.
0920 - The request for fighter protection was repeated by the Commanding Officer of “Tirpitz" and the fighters took off immediately.
0927 - At a distance of approximately 30 miles from Tromsoe, the first bomber formation in response to a smoke signal split into groups of 4 to 5 planes and started in on an attack course. The planes came from the direction of the sun and the course, in contrast to previous tactics was athwartships.
0934 - Heavy AA guns opened tire at a range of about 7 miles, causing only a slight breaking up of the formation, the bombers joining together again immediately.
0936 - Medium AA and machine guns opened fire but the bombers continued straight through. One plane was observed to fall during the approach. Note: Not shown on plates, located on lower platform, starboard and port respectively, outboard, between frames 145.6 and 154.5.
0938 - A closed bomb carpet of 29 "Tallboy" 12,000 pound bombs was dropped on "Tirpitz". There was one confirmed direct hit and probably two others (Plate I). All hits were on the port side. Numbering these bombs for convenience from forward, No. 1 (classified as "probable") according to reference (d), struck near turret “Bruno". No. 2 made a confirmed direct hit near the aircraft stowage detonating in a wing tank outboard of the port engine room (Turbineraum Bb.), (Plate II). According to reference (a) Bomb No. 3 (the second probable) struck abaft of and to port of turret “Caesar". No. 3 was reported to have caused a fire. There were no reports or indications of any other direct hits.
In addition to the direct hits, approximately 7 other bombs landed to port of "Tirpitz" within the torpedo net, 2 or 3 very close to the ship's side. (Plate III). Ten borne craters in the sea bottom were visible from the air. There were no reports of any bombs landing to starboard of the centerline, either on the ship or nearby.
Large quantities of water swept into and over the "Tirpitz”. She listed rapidly to an angle of about 35 degrees. AA fire decreased sharply. At the start of the list the order was given to counterflood. It was discovered later that the flooding controls had been abandoned. It is not known whether these controls were abandoned before the valves could be opened. The main drainage pumps were not used. Personnel were instructed to evacuate the lower decks. The port side of the superstructure dock went under and the list increased to about 60 degrees, remaining there briefly.
0945 - Turret “Caesar” exploded, cause unknown,. all rotating structure reportedly being hurdled about 25 yards through the air. The immediate effect of the explosion was to increase the list so that the ship capsized, approximately 7 minutes after the first bombs landed. “Tirpitz" came to rest on the floor of the anchorage at an angle of about 135 degrees with the superstructure embedded in the mud.
Electricity was furnished by the turbo generator in generator room until the very end. There were no indications of panic during or after the capsizing. About 1,200 officers and men were lost, and about 600 saved.
(a) Type of Bombs.
According to references (a) and (c), the, bombs used against "Tirpitz" on 12 November 1944, were the "Tallboy" type. Two previous attacks had been made against "Tirpitz" using "Tallboy" bombs. However, smoke, screens had then prevented any serious damage. "Tallboy" has a total weight of 12,000 pounds, including 5,200 pounds of Torpex. filling. There are 3 fuzes and 3 exploders of special design in the tail, giving a range of, fuze settings from instantaneous to one-half to one hour delay. For attacks on shipping a 0.07 and 0.05 second delay have been used.
Eighteen of the bombers used S.A.B.S. Mk. IIa Tachometric sights, while 12 planes were equipped with Mark XIV vector sights. Analyses pf the most recent daylight attacks with S.A.B.S. at altitudes averaging 13,000 test indicate about 5 percent gross errors and an average radial error of 195 yards. "Tallboy" was not designed for armored targets but for deep penetration into the ground and for maximum earth shock. It is interesting to note that a "Tallboy" bomb contains about 5 times the weight of explosive carried by the largest torpedo used by any Navy during this war. It is reported in reference (a) that the detonation of one of these bombs in the water about 60 feet from "Lutzow" led to the loss of that vessel.
(b) Structural Damage.
Information concerning the structural damage is only partially complete, being based on divers' inspections which were halted due to dangerous working conditions (reference (d)). None of the bombs apparently caused any damage on the starboard side outboard or in the large interior spaces on the starboard side.
On the port side from stern to frame 98 there was no apparent damage except for shrapnel bolas in the vicinity of frame 98. Between frames 98 and 132 the outer skin was torn away. Probably a considerable portion of the torpedo bulkhead was ruptured in this area, the torpedo defense system on "Tirpitz" being designed to withstand only about 660 pounds [300 kg] of German hexanite. Forward of frame 132 there were no signs of damage except for shrapnel holes near frame 132 and the damage from a previous attack mentioned in paragraph 1,b.
Damage occurred to port of the centerline in the following parts of the ship, at least (Plate III):
(2) Port engine room, in Section X (Turbineraum Bb.)
(3) Port fireroom No. 1, in Section XI (Kesselraum, Bb.h.)
(4) Section XII
(5) Port fireroom No. 2, in Section XIII (Kesselraum Bb.v.)
(6) Section XIV
(c) Explosion of Turret “Caesar".
Turret "Caesar" exploded from an unknown cause about 7 minutes after the first bombs landed (paragraph 2). Fregatten Kapitan (Ing.) Eichler stated that while, the ship was listed to 60 degrees all the rotating structure, weighing about 1,000 tons, suddenly was hurled out of the barbette and through the air about 25 yards.
The reason for this explosion is not known definitely. The results of an interrogation referred to in reference (a) indicate that a bomb may have struck the ship abaft and to port of Turret "Caesar", causing a fire. Such a fire could have led to the explosion. The divers' examinations apparently did not interior of the ship in the neighborhood of Turret "Caesar".
On the other hand, Eichler claimed that the ship was not hit by a bomb in the vicinity of turret “Caesar”. According to him, “Tirpitz" had in her magazines an unusually large amount of powder. Although regulations in the German Navy, based on war experiences and underwater tests, required that such ammunition be stowed horizontally and longitudinally, some powder had to be stowed transversely. Eichler's theory was that a non-contact detonation had forced in the ship’s side sufficiently to cause some of the transversely stowed powder bags to be ignited, However, the divers' reports indicate that, the shell plating is intact from frame 98 to the stern. It seems quite improbable that powder protected by a torpedo system could be damaged seriously enough to cause an explosion if the shell plating were not badly ruptured.
Short circuits of electrical equipment caused by the shock of detonations within and close to the ship may have started fires in the magazines.
(d) Number and Locations of Direct Hits.
Reference (d) mentioned only two direct hits, one, near turret "Bruno" and a second amidships near the plane stowage. Since the divers' examinations were halted before bomb hit No. 1 could be verified, this bomb, is classified as “probable” (Plate I). The damage incurred by No. 2 was reported by the divers. References (a) and (b) state that there were three direct hits altogether. As mentioned in the section on the explosion of turret "Caesar", an interrogation referred to in reference (a) indicates that a bomb detonation near turret "Caesar" resulted in the explosion of that turret. On the other hand, the, interrogation of Fregatten Kapitan (Ing) Eichler indicates that a bomb may not have struck near turret "Caesar" and there may have been another factor causing the explosion. Since there appears to be a reasonable doubt, Bomb No. 3 is considered a "probable".
(e) Flooding, Stability and Damage Control.
As mentioned in paragraph 1, damage from previous attacks had resulted in a number of spaces in the bow and stern of “Tirpitz” still being flooded prior to the attack of 12 November. The fuel and fresh water on board were about 30 percent of full load (paragraph 2). Calculations indicate that under the above condition of loading and with the minor flooding in the bow and stern, the displacement prior to the final attack was about 42,000 tons, at a corresponding mean draft of about 29.0 feet and a GM of about 12.0 feet. In order not to reduce the reserve buoyancy, the one degree port list had not been removed by counterflooding.
The spaces flooded immediately, therefore, may have included at least the after engine room (Turbineraum m.h.), the after middle fireroom (Kesselraum m.h.) and all spaces between frames 83 and 154.5 beneath the armored deck and to port of the centreline. In addition, the detonation of Bomb No. 2 undoubtedly destroyed the watertight integrity of upper deck spaces in the immediate vicinity.
The capsizing took place in three stages: approximately 35, 60 and finally 135 degrees. The immediate flooding was sufficient to cause the vessel to list rapidly to about 35 degrees. The initial stability of "Tirpitz" undoubtedly had been impaired somewhat by the fact that the amount of fuel oil and fresh water, stored in tanks low in the ship, was about 7,000 tons less than for full load. Since it was not customary to ballast fuel oil tanks with seawater, no compensation had been made for the fuel oil removed. Also, the torpedo protection system for German battleships is designed with the empty tanks used for counterflooding outboard of the wing liquid storage tanks (Plate II). When some of the empty counterflooding tanks on the port side of "Tirpitz" were ruptured, the listing moment was much greater than if they were inboard of the wing storage tanks. Furthermore, some of these wing storage tanks, likewise unballasted, probably were empty or partially empty prior to rupture, and their flooding may have added considerably to the port listing moment.
At an angle of 35 degrees a balance was reached between the listing moment created by the sea water in the port spaces and a righting moment produced by the inherent stability characteristics of the ship, possibly assisted by the reaction of the mud on the floor of the anchorage.
Even though counterflooding were to result in loss by bodily sinkage, salvage of “Tirpitz” resting upright on the floor of the anchorage would have been much easier than raising her after capsizing. For this reason, at the start of the list orders were issued to counterflood. Although communications to some stations may have been disrupted, the Repair Parties had standing instructions to open the sea valves to all counterflooding tanks on the side opposite a list as soon as the list reached 5 degrees. It was discovered later that the counterflooding valves had been abandoned. It appears unlikely that well trained men would leave their stations before opening the valves. Moreover, there were no indications of panic among the crew.
It would appear that the counterflooding system was not designed to check such a rapidly increasing list. Undoubtedly, there was some delay in manning the various flooding stations and in turning the reach roads to open the sea valves. In addition, it is quite possible that the valves had openings too small to handle rapidly enough the required amount of water. By the time “Tirpitz” had been inclined to an angle of 35 degrees, the sea connections to the starboard counterflooding, tanks might have been out of the water. (Plate II).
Although the time is not known definitely, it is probable that while the list was still steady at about 35 degrees the orders to evacuate the lower decks were issued. The resultant loss in water-tight integrity caused by the opening of accesses during the evacuation seems to have been the cause for increasing the list to 60 degrees. Calculations indicate that after the evacuation was underway there may have been as much as 17,000 tons of sea water in "Tirpitz", causing a listing moment of about 450,000 foot tons. Normally, the ship would have continued on over. However, a balance was reached at 60 degrees, apparently because the ship' s bottom was resting against firmer soil.
While "Tirpitz” was inclined at 60 degrees, turret “Caesar" suddenly exploded, the whole rotating structure being hurled out of the barbette. The reaction from this explosion upset the balance and the ship capsized.
The loss of "Tirpitz" indicates the effectiveness against large combatant vessels of giant bombs properly fuzed and containing massive explosive charges.
The circumstances were extremely favorable for a successful attack. The visibility and wind conditions were excellent. Altogether, twenty-nine 12,000 pound bombs, each with a 5,200 pound Torpex filler, were dropped on a single target lying at anchor. All bombs apparently landed on one side of the ship's centerline.
"Tirpitz" incurred severe structural damage on the port side. There was at least one direct hit and probably two others. In addition, bombs detonating in the water close to the ship broke down the torpedo protection system and were a vital factor in the capsizing. There was no evidence of damage to the starboard side from this attack.
A sudden, tremendous inflow of water filled a major portion of the port side, causing the vessel to list rapidly to about 35 degrees.
The missing 7,000 tons of fuel oil and fresh water had the same detrimental effect on the initial stability as the removal of a corresponding low weight. Liquid ballasting was not added to compensate for the fuel consumed.
That part of the listing moment caused by the flooding of ruptured port counterflooding tanks was much greater than if these tanks had been located inboard of the wing storage tanks.
A considerable part of the listing moment may have been caused by the flooding of unballasted wing liquid storage tanks.
Counterflooding was ineffective, possibly because the sea valves were opened too slowly and when opened were too small to handle rapidly enough the enormous amount of water required to check the list.
The breakdown of the watertight integrity, resulting from the order to evacuate the lower decks, eliminated all possibility of keeping the ship afloat.
E. B. HITCHCOCK
To: CPVA (Chemical Physical Research Institute)
Re: Sinking of ”Tirpitz”
Enclosed data concerning the sinking of “Tirpitz” are returned as being under your cognizance. A copy of the data is to be sent to this office (FEP).
1 Note: This translation avoids the dispatch style of the originals for the sake of clarity.
Appendix (A-2) (Dated 19 November 1944)
This report is based on eyewitness accounts and weather forecasts. Weather: clear, visibility very good. The attack was made from the direction of the sun as the sun rose: wind SSW, force 1. A watch had been set aboard ship since daylight.
0800 - Received first warning concerning single bombers around Bodoe. Ship was connected immediately to the main air raid warning station at Tromsoe (direct connection).
0815 - Received further warning from FMZ that 3 Lancasters (tactical time 0737) with Mosquito fighter escort were flying in on an easterly course. More Lancasters were reported coming in on a northeasterly course so that the ship command expected a repetition of the attack of 29 October (Swedish Territory). Fighter protection was requested through FMZ. No acknowledgement so far.
0850 - Report received from warning station of an HMB north of Tromsoe coming into TEMOS, Sector Z, Course west. Since the report came from north of Tromsoe, it was considered unreliable.
0854 - An air raid alarm was sounded for the ship and the city of Tromsoe. No further report was received from the warning station until the sighting of the bomber formation.
0915 - Enemy formation of approximately 20 to 25 aircraft was sighted approaching. (AA Post reported 19 planes; range 120 kilometers). At a range of 90 kilometers the planes headed toward “Tirpitz”. At this time, the warning station at Tromsoe reported the approach of a second formation. Shortly thereafter, this second formation was sighted from “Tirpitz” also. (AA post reported 14 planes). The altitude of both flights was approximately 300 meters.
0920 - The request for fighter protection was o repeated o by order of the Commanding Officer of "Tirpitz". The fighters took off immediately.
0927 - At a distance of 50 kilometers from Tromsoe the first bomber formation, in response to a smoke signal, split up into groups of 4 to 5 planes and started in on an attack course. In contrast to previous tactics, the course was athwartships.
0934 - Heavy AA guns opened fire at a range of 12 kilometers and consequently caused only a slight breaking up of the formation. The bombers immediately resumed formation.
0936 - Medium AA and machine guns opened fire. The enemy planes continued straight through. During the approach one plane was seen to fall.
0938 - A closed bomb carpet was dropped on a single target, "Tirpitz”. Included were many hits by heavy caliber bombs within the torpedo net on the port side and two direct hits on the port side of the ship, one of which hit near turret “Bruno” (Lt. Fasbender in charge). Large quantitied of water swept over the ship, accompanied by an increasing list until the port side of the superstructure deck was under water. There resulted also a decrease in AA fire and a number of personnel and material casualties. At the start of the list, the command was given to counter-flood. This order probably was not carried out as it was later discovered that the flooding controls no longer were manned. Further bomb hits were not clearly observed.
0945 - “Caesar” turret exploded, cause unknown. The immediate effect was to increase the list and start the ship to capsize to a final angle of 135 degrees. Shortly before the explosion, the order was given to evacuate the lower decks. As a result the watertight integrity of the entire ship was broken, thereby influencing the subsequent capsizing. All the times mentioned above may be slightly in error.
Conduct of the Crew
The commanding officer told the crew before the attack that another major raid was imminent and that the crew of "Tirpitz” would stand fast, show their teeth to the enemy and repulse the attack. As the list increased, a further command was given: "Fire everything possible!" The crew carried on bravely in spite of the tremendous effect of the bombing and heavy casualties. The conduct was completely disciplined. There was no panic during or after the capsizing.
Appendix (A-3) (dated 23 November 1944)
In connection with the attack on "Tirpitz", it is reported further:
(1) Nearly 46 tons of the heaviest type of bombs landed within the torpedo net close to the port side of “Tirpitz”. There were definitely two bomb hits on the port side of the ship, and no bombs or near misses on the starboard side.
(2) According, to results of investigation, there was no damage (except for older known damage) on the starboard side outboard or in the large interior spaces on the starboard side.
(3) "Tirpitz" had a list of one degree to port before the start of the attack. In order to prevent a loss of reserve buoyancy, this list was not eliminated by counterflooding.
(4) On 12 November the supply of fuel oil and water on board was approximately 3,000 tons; this is compared with a full load value of about 10,000 tons.
(5) The ship’s watertight integrity was probably broken down by the order to clear the lower decks.
(6) The probable cause of capsizing was the combined effect of (1) to (5).
(7) A sudden, tremendous inflow of water nearly filled the entire port side of the ship.
(8) The beginning turning moment to port was accelerated by the buoyancy of the starboard side and reinforced by the 7,000 tons of liquid not on board.
(9) It is to be presumed that great changes took place on the bottom of the cage (? - probably floor of anchorage) as confirmed after the raid of 29 October.
(l0) Concluding observations: preservation of the ship was made possible only by placing the ship in very calm water, while recognizing the known disadvantages, including the risk of the most severe damage. In anchoring in shallow water, the ship would only sink to an upright position if flooding were equal on both sides of the ship. The dynamic effect of such a one-sided mass of water was beyond human imagination and unknown at the time of planning and building the ship.
The experience at Scapa Flow may be mentioned: all the large warships ("Seydlitz", "Moltke") capsized without exterior damage in calm water, except “Hindenburg" which also was in calm water and took two hours to sink.
Appendix (A-4) (dated 24 November 1944)
The fact that the supply of water and fuel oil on board was 7,000 tons less than full load (mentioned in the supplementary dispatch of Comm. Adm. POLARK, dated 22 November concerning the attack on "Tirpitz" would increase the freeboard approximately 1.2 meters according to today's discussion. It is not known why counterflooding of empty tanks to reach a balance, was not undertaken by the command.
Signed MOK, Norway
Appendix (A-5) (dated 10 December 1944)
The diver's investigation of the bottom and port side of "Tirpitz" was halted because of the danger to the diver in penetrating further into the torn shell plating and also because of the short period of daylight.
The investigation revealed considerable information concerning the damage. The lower edge of the port waterline armor projects slightly out of the mud. From the stern to frame 98, there is no damage except for shrapnel holes in the vicinity of frame 98. Between frames 98 and 132 the outer skin is torn away. Forward of frame 132 there is no damage except for shrapnel holes near frame 132 and previously confirmed damage at the bow.
Damage occurred in the following parts of the ship:
(a) About 15 frames in the middle turbine room and Section IX.
(b) Frame 98 to 112, Section X (port turbine room).
(c) Frames 112 to 127, Section XI (Boiler room No.1).
(d) Frames 127 to 132, Section XII (Boiler auxiliary machinery room).
(e) Approximately 15 Frames comprising Section XIII (Boiler room No. 2).
(f) Electric Generator Room No. 4.
The most severe damage of all seems to have resulted from direct hits on the ship near the plane stowage, a location checked by shore observation. In that location a bomb went through all decks and armor, detonating in a filled wing tank near the torpedo bulkhead of the port turbine room. In way of the port turbine room (for about one-third of the ship' s breadth) the shell plating and waterline armor had completely disappeared, and the bilge keel and ship's bottom were also missing up to the cooling-water discharge sea chest. In this location the edges of the longitudinal bulkhead (probably torpedo bulkhead) bent inward and torn wide open. According to observers, the capsizing took place in three stages, the ship listing to 35°, 60° and 135°. This progression probably was due to the flooding of the additional spaces opened up by bomb hits, pierced bulkheads, and incomplete closures (caused by evacuation of lower decks). The above conclusion is difficult to prove, because the damaged locations will never be accessible, due to reasons mentioned earlier.
Endorsement by Adm. POLARK
The investigation confirms the previous belief that the opening of the port side at an important location was the deciding factor in the loss.
Drawing showing the path of Bomb No. 2 and the spaces established later by divers’ inspections as having been damaged.
This drawing illustrates the estimated point of detonation of Bomb No. 2 in a wing tank on the port side, and the different listing angles, 1º, 35º, 60º, and 135º.
Estimated point of detonation of Bomb No. 3 abaft of and to port of turret “Caesar".
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