The Wreck of DKM Bismarck − A Marine Forensics Analysis 1 The ...

More documents

Recommendations

Info

The Wreck of DKM Bismarck − A Marine Forensics Analysis patches over the entrance and exit holes to repair the damage at the bow. The plates to cover the entrance and exit holes were cut and ready to install. This plan was rejected by Admiral Lütjens, as it would involve slowing the ship and creating a list to port or starboard to permit the repairs. From pictures, it appears the bow was down 1.5 to 2.5 meters, so one could anticipate a commensurate rise at the stern. In fact, the underside of the stern was clear of the water in one picture. Survivor accounts say the starboard screw was running with its blade tips out of the water after the 24 May battle. Captain Lindemann ordered the flooding of starboard voids in Compartments II and III in the stern to restore trim and list, but it is unknown how effective this was. Presumably, trim was not fully restored. Unfortunately, these counter flooding measures increased draft and decreased the overall freeboard. This could have been a factor in later events, since a lower freeboard meant less reserve buoyancy. A lower freeboard made it more difficult to hit below the main side belt when firing at close range. Close-range gunfire is more likely to have shells ricochet off the water surface, substantially reducing the likelihood of shells having an underwater trajectory. THE CHASE ─ 24 May through 26 May 1941 Bismarck was hit by one torpedo dropped by a Swordfish torpedo bomber launched from HMS Victorious the evening of 24 May. This contact detonation, on the starboard side in way of the 320-mm main side belt armor was not a factor in the ultimate destruction of the German This minor damage on the starboard side amidships was caused by an aerial torpedo the evening of 24 May 1941. The torpedo detonated against the 320-mm main side belt armor, failing to penetrate. The gouges in the upper (145-mm) and main side belts are from hits by 203-mm or smaller caliber shells that did not penetrate. 12
The Wreck of DKM Bismarck − A Marine Forensics Analysis battleship. Minor flooding resulted, as the belt armor displaced inboard and damage control packing in way of the shell hit in way of Compartments XIII and XIV was loosened. Overnight, Bismarck broke contact with her British pursuers and headed for shelter and major repair facilities at the Penhoet-Loire Shipyard in St. Nazaire, France. The heavy cruiser Prinz Eugen was detached to continue the originally-planned commerce-raiding mission into the Atlantic. After an interval of 31 hours, the German battleship was spotted by a British Catalina aircraft, piloted by an American naval aviator, ENS Leonard B. (“Tuck”) Smith. 14 This sighting permitted aircraft from HMS Ark Royal to attack the German ship during the evening of 26 May. If the Germans were not diverted from their course to France in the next few hours, they would soon be within range of friendly shore-based aircraft and likely out of danger, despite the best efforts of the men and ships of the Royal Navy. At this time, the light cruiser Sheffield was shadowing the German ship. Fortunately, as matters turned out, the Royal Navy aviators, unaware of the presence of the friendly cruiser, attacked one of their own ships! This near-tragic incident was of enormous importance, since the men on the cruiser reported that those torpedoes directed at their ship detonated prematurely. It was judged that the magnetic-fused detonators fitted to the torpedoes were defective. When a last-gasp attempt by Swordfish torpedo bombers to stop Bismarck was launched later on the afternoon of the 26 th of May, more reliable contact fuses were installed. The torpedoes were also set for a relatively shallow running depth, about three meters. This attach was successful, scoring three torpedo hits. Two hits amidships caused relatively inconsequential damage ─ minor inboard flooding was caused by a hit on the port side, in way of Compartment VII. The detonation severed the degaussing system cable in the vicinity. The damaged cable can be seen adjacent to the torpedo hole. A second hit on the starboard side in way of Compartment VII caused some flooding, which was confined to the side protective system. Unfortunately for the Germans, the third torpedo detonated in the stern near the starboard rudder. This damage caused the instantaneous and devastating loss of steering control. THE MORTAL TORPEDO HIT Identification of torpedo hits was extremely difficult except for the mortal torpedo hit in way of the rudders. It is very important to remember that water was frequently forced out by the phenomenon of hydraulic outburst, discussed later in this paper, even where there were no preexisting holes. We believe this phenomenon accounts for the majority of the damage to the lower hull. Jim Cameron’s team clearly imaged an area on the port side where the lower hull shell was detached from the main side belt and the plating forced outward, but the separation attenuated to zero both forward and aft, and there was absolutely no evidence of torpedo or shell damage in the vicinity, thus indicating the start of the hydraulic outburst process which was stopped before the lower hull section completely detached. The forensic evidence at the wreck site strongly supports the conclusion that any pre-existing torpedo or shell damage acted to stop the propagation of cracks running along the joint between main side belt armor and the lower hull shell, probably by acting as a relief valve to vent the overpressure. When a crack is running in a piece of plexi-glass, for example, a hole is drilled ahead of the crack and that measure halts the crack propagation at the hole. We believe what is seen on Bismarck is a similar mechanism on a much larger scale. Almost all the damage that the team has seen from the May 2002 survey 14 As related by CAPT Leonard Smith (USN, Ret.) in correspondence with author William Garzke. 13
Page 1 and 2: The Wreck of DKM Bismarck − A Mar
Page 11: The Wreck of DKM Bismarck − A Mar

The Wreck of DKM Bismarck − A Marine Forensics Analysis 1 The ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?