Originally Posted by BritinAfrica

HMS Hood blew up because a shell from Bismark penetrated her deck armour and exploded in one of the magazines. She should have been refitted with heavier deck armour but operational and goodwill cruises kept her out of the dockyards.

I don't think there is much evidence that this was the case

An extensive review of each of these theories (except that of Preston) is given in Jurens. Its main conclusion is that the loss was almost certainly precipitated by the explosion of a 4 inch (102 mm) magazine, but that there are a number of ways in which this could have been initiated. In Jurens' opinion, the popular image of "plunging fire" penetrating deck armour of Hood is inaccurate, as by his estimation the angle of fall of Bismarck's 38 cm shells at the moment of the loss would not have exceeded about 14 degrees, an angle so unfavourable to penetration of horizontal armour that it is actually off the scale of contemporary German penetration charts. Moreover, computer-generated profiles of the Hood show that a shell falling at this angle could not have reached an aft magazine without first passing through some part of the belt armour. On the other hand, the 12 inch (305 mm) belt could have been penetrated, if the Hood had progressed sufficiently far into her final turn.

http://en.wikipedia.org/wiki/HMS_Hood_(51)

Perseus

No I think BriAfrica is right on this.

The history channel did a good summery

http://www.youtube.com/watch?v=3ib7j...eature=related

I started from Part II, because that concerns the Hood, but feel free to watch the whole series its pretty good. The CGI is amazing...

You have good testimony from a survivor from Hood (there are only 3) and also some crewmen from Bismark as well...

Originally Posted by perseus

I don't think there is much evidence that this was the case http://en.wikipedia.org/wiki/HMS_Hood_(51)

Actually there is:-

http://www.hmshood.com/history/denma.../bismarck3.htm

The First Board of Enquiry
The first enquiry was convened in early June. They quickly reached the conclusion that one or more shells from Bismarck had managed to penetrate Hood’s armour/protective plating and detonate her aft magazines. Although it was a logical conclusion, the proceedings came under scrutiny: As it turned out, very few witnesses were called, and of the Hood survivors, only William Dundas gave evidence. Verbatim records of the evidence were not made and to make matters worse, the appropriate experts (on explosives, etc.) had not been called. It was not long before the Admiralty decided that a second board would have to be convened.

The Second Board of Enquiry
The second Board convened on 27th August 1941 under the Chairmanship of Rear-Admiral H.T.C. "Hooky" Walker, himself a former Captain of Hood. This board called two of the three survivors (Ted Briggs and Bob Tilburn), numerous eyewitnesses from Prince of Wales, Suffolk and Norfolk. It also called experts in the fields of construction and armament/explosives. Although far more comprehensive and thorough than the first enquiry, the second Board ultimately reached much the same conclusions as the first Board – A salvo from Bismarck penetrated Hood’s vitals and detonated the aft magazines. Other possibilities exist, but a shell from Bismarck was felt to be the most likely cause.

The Discovery of Hood’s Wreck
In July 2001, a team led by David L Mearns located Hood’s wreck approximately 9,200 feet below the surface of the Denmark Strait. The team also visited the wreck of Bismarck. In the case of Hood, the condition of the wreck confirmed that a catastrophic event involving the aft magazines did indeed cause the destruction and sinking of the ship. The damage was actually much more severe than initially expected- not only was the stern detached, but the bow (seen in the photo to the right) was separated from the main hull as well.

For detailed photos and an in-depth description of both the Hood and Bismarck wrecks, please see our article on The July 2001 Channel 4 Expedition to Locate and Film the Wrecks of Hood & Bismarck.

Mmarsh and BitinAfrica

The graphics on the History Channel were very entertaining so thanks for this. I'm not sure where they got the information from though because Jurens work is highly detailed and widely quoted in modern studies of this. I also recall seeing a modern 'history' programme less dramatised than the one you linked, that quoted these figures

Depending upon the exact location of the hit, a shot perforating the 127mm belt would still have to penetrate approximately 160-180mm of deck armor in order to reach the magazines. If the hit went through the 178mm belt instead, only about 130mm of deck penetration would have been required, but in compensation the shell would have been traveling much more slowly. In either case the trajectory of the projectile, its velocity, and its high obliquity would have rendered useful penetration to the area of the magazines highly unlikely. Even assuming the projectile were not rejected or deflected by Hood's deck armor, the fuze delay of the German projectiles would have probably detonated the shell before it could reach a magazine. Assuming that the required deck penetrations reduced the projectile's average velocity to half of the plate exit velocity, a nominal fuze delay of 0.035 seconds corresponds to a travel of only eight meters at best, not enough to reliably reach a magazine.

http://www.warship.org/new_page_1.htm


Also see See Addendum I: Hood's Deck Thickness

this suggests that Hood's armour distribution for a given overall weight was in fact entirely suitable, even optimised for engaging a WW2 battleship !

http://www.navweaps.com/index_inro/INRO_Hood_p4.htm

From accounts of the battle I have read and programmes I have watched, HMS Hood received a plunging shot from Bismark on her aft deck as she was trying to maneuver to port, smashing through the deck armour into her magazine. David Mearnes dive team who inspected HMS Hood are of the opinion that the magazine did explode causing her to break apart with massive loss of life.

The only ones who can really be sure why HMS Hood sank are all dead.

HMS Hood are of the opinion that the magazine did explode causing her to break apart with massive loss of life.

Yes of course, that is what the evidence suggests, but the issue is was the deck too poorly protected as widely assumed?

I have to admit I am not sure how the Bismarck could have generated plunging fire when her guns were design as low trajectory weapons, this was the key to its ability for rapid fire, low trajectory generates a splash much quicker and in turn the guns can be redirected faster.

Plunging fire can usually be obtained at extreme range providing the gun can be elevated enough, this is why Holland came in close as quickly as possible to avoid this. Since he was turning or just turned at the time of the explosion this suggest to me he was confident that the threat of plunging fire at that range had been minimised.

Not sure what this refers to but I guess it would look something like this (if we expand the scales). I don't think the Bismark could elevate the guns more than about 30 deg though.



Baffles me through why if you have two capital ships why you don't space them apart at 45-90 degrees (in the plan view now) to the main target so you can get always get a near perpendicular hit on the belt armour? Conversely if your opponent has only one capital ship surely you would attempt to angle your ships so the armour is always at a sufficiently acute angle to the incoming shots, enough so you can get still a broadside.

Originally Posted by perseus

Yes of course, that is what the evidence suggests, but the issue is was the deck too poorly protected as widely assumed?

As far as I am aware, HMS Hood was trying to reduce the range to counter plunging fire.


http://www.warship.org/no21987.htm

The addition of extra armor in the final design represented a significant improvement; without it, the immunity zone1 against German 380mm shells would actually have been negative. Despite the addition of some 3,450 tons of additional armor and protective plating, however, Hood was still considered vulnerable to long range fire. Although several schemes were put forward to update her over the years, none were ever carried out. Although as late as 1940, Jane's Fighting Ships was stating that ". . . the general scheme of protection is most comprehensive," in Admiralty circles her actual protection was always considered marginal. In 1920, trials with built up targets representing Hood were conducted and showed that her magazines could be reached by a 15-in shell penetrating the 7-in [178mm] belt. In a number of almost incredibly prophetic diagrams, the Admiralty sketched the path of the shells and showed how the addition of 3-in [76mm] of additional deck armor could have prevented potential disaster.

What the video states is that Vice Admiral Holland was trying to reduce the range because he knew that HMS Hood weak deck armor wouldn't withstand a plunging fire hits. He made a fatal mistake however, he thought he had closed the range sufficiently and turned Hood and Prince of Wales to Port too early in order to bring their full broadsides to bear. In reality he was still well within plunging fire range and a lucky hit ended the most famous ship in the RN.

Remember HMS Hood was a BattleCuiser not a Battleship, Battlecruisers carried the armament of a Battleship but their speed and armor was that of a Heavy Cruiser.