Battleship Vanguard Armor

Warship design and construction, terminology, navigation, hydrodynamics, stability, armor schemes, damage control, etc.
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Re: Battleship Vanguard Armor

Postby alecsandros » Mon May 13, 2013 10:01 am

RF wrote:
Dave Saxton wrote:
I think the example of POW being so easily sunk by the Japanese demonstrates that the design wasn't that much of a success.

Well perhaps,
But the crippling torpedo impact arived at an unarmored [and probably un-armorable] section of the ship... all vessels that I know of were instantly crippled after receiving hits on the shafts/ruderrs... [Bismarck, Veneto, Prinz Eugen... etc]

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Re: Battleship Vanguard Armor

Postby RF » Mon May 13, 2013 5:08 pm

But there is a difference between being crippled and being sunk - the fate of Bismarck amptly demonstrates this with the difficulty Tovey had in sinking a crippled ship which was almost a sitting target.

POW was sunk with hardly more torpedoes than Royal Oak or Barham, indeed if I recall correctly with fewer torpedoes than Repulse.....
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Re: Battleship Vanguard Armor

Postby Dave Saxton » Tue May 14, 2013 3:52 pm

We don't know if a G3 could have performed any better, or as good. However, the British did find the KGV system flawed, as evidenced by the revisions incorporated into Vanguard. To reduce the intractable vulnerability of the shafts, it was reccomended that future contruction also adopt a 3 shafts lay out. This could not be done for Vanguard because the machinery was to be that already ordered for the Lion.
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Re: Battleship Vanguard Armor

Postby dunmunro » Wed May 15, 2013 8:12 pm

The RN based their assessment of flaws in the KGV prop shafts on the assumption that the shafts failed instantaneously upon being hit by a torpedo when this was not the case and, in fact, there was no major flaw in the shaft design, but this was not known conclusively until very recently with the latest wreck surveys of PoW.

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Re: Battleship Vanguard Armor

Postby Byron Angel » Thu May 16, 2013 11:49 am

dunmunro wrote:The RN based their assessment of flaws in the KGV prop shafts on the assumption that the shafts failed instantaneously upon being hit by a torpedo when this was not the case and, in fact, there was no major flaw in the shaft design, but this was not known conclusively until very recently with the latest wreck surveys of PoW.



Please clarify. Physical inspection by diver of PoW's shaft alley spaces indicates that, after the torpedo hit ruined the exterior shaft strut, it was actually the continued operation/rotation of the now unseated propeller shaft that destroyed the shaft seals, opened up the shaft alley and produced uncontrollable flooding into the aft engine room spaces. Are we therefore saying that the ability of the shaft to continue in operation after the torpedo hit (i.e. not suffer instant failure) demonstrated the soundness of the shaft design?

I'm not necessarily seeking to dispute anything, just interested to put the commentary in proper context.

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Re: Battleship Vanguard Armor

Postby dunmunro » Thu May 16, 2013 6:12 pm

Byron Angel wrote:
dunmunro wrote:The RN based their assessment of flaws in the KGV prop shafts on the assumption that the shafts failed instantaneously upon being hit by a torpedo when this was not the case and, in fact, there was no major flaw in the shaft design, but this was not known conclusively until very recently with the latest wreck surveys of PoW.



Please clarify. Physical inspection by diver of PoW's shaft alley spaces indicates that, after the torpedo hit ruined the exterior shaft strut, it was actually the continued operation/rotation of the now unseated propeller shaft that destroyed the shaft seals, opened up the shaft alley and produced uncontrollable flooding into the aft engine room spaces. Are we therefore saying that the ability of the shaft to continue in operation after the torpedo hit (i.e. not suffer instant failure) demonstrated the soundness of the shaft design?

I'm not necessarily seeking to dispute anything, just interested to put the commentary in proper context.

Byron


Yes "continued operation/rotation" caused by restarting and running the damaged shaft at near full power! This was a damage control failure, as the shaft itself was able to survive the initial damage with only limited damage to the shaft bearing and seals until the shaft was restarted and run to destruction. The failure lay in restarting the shaft after it was initially stopped and then running it up again - no shaft can be run at near full power with no external strut and damaged rear seals/bearings! However, this was what happened and it inevitably led to fatal destruction and flooding all along the shaft alley up the engine room.

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Re: Battleship Vanguard Armor

Postby RF » Thu May 16, 2013 6:47 pm

I am wodering why the POW's Chief Engineer didn't consider this danger when the order to restart came through - presumably in the heat of the action the need to get the ship moving was paramount, but I am mindful of the request made to Lindemann on the last night of Bismarck by their Chief, even though it was known that British ships must be close by.
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Re: Battleship Vanguard Armor

Postby dunmunro » Thu May 16, 2013 7:04 pm

RF wrote:I am wodering why the POW's Chief Engineer didn't consider this danger when the order to restart came through - presumably in the heat of the action the need to get the ship moving was paramount, but I am mindful of the request made to Lindemann on the last night of Bismarck by their Chief, even though it was known that British ships must be close by.


There never was an order to restart the shaft as communications failed just after the hit. The OiC of B ER stopped the shaft, after it was apparent that it had suffered damage, and then on his own initiative restarted it again. This was contrary to established procedure, as he did not physically inspect all the shaft bearings along the shaft alley before restarting it.

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Re: Battleship Vanguard Armor

Postby steffen19k » Wed Jun 04, 2014 11:35 pm

Well, I'm back after a somewhat long hiatus.

I guess what I'm curious about in all this is the idea of influence detonations.

I know both the US and the Germans tinkered with magnetic detonators that were meant to permit the torpedo to blow up UNDERNEATH the vessel and break its back, at which point the hull structure would do its own self destruction.

During Vanguards tenure, what was her likelihood of facing influence detonators? Mines or torpedoes?

Further; What would a torpedo blowing up 6 feet under her keel at regular spacings have done to her structure?
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Re: Battleship Vanguard Armor

Postby tommy303 » Fri Jun 06, 2014 4:55 pm

Magnetic mines and torpedoes were considered a very lethal threat to any vessel unfortunate enough to encounter one if the magnetic pistol worked properly. At the time Vanguard came into service, magnetic mines and torpedoes had been quite well perfected and were much more reliable than those employed early in the war. Large vessels like Vanguard normally had degaussing coils built in to them for protection against such weapons. These reduced the magnetic field around the vessel to below that which would activate the mine or torpedo pistol. Post war, however, magnetic pistols became even more efficient and utilized a system which would sense any change in the magnetic field, allowing even a degaussed vessel to be attacked; this led to a post war mini technology race in improved degaussing vs improved magnetic weapons.

Typically, even if structural damage was minor, a non contact detonation would still cause enormous damage to various ship systems--ie shock damage to radars, optical fire control instruments, turbine alignment, and so forth, depending on the size and strength of the warhead.

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Re: Battleship Vanguard Armor

Postby steffen19k » Wed Jun 11, 2014 2:55 am

My question was more about the survivability of Vanguards structure against the weapons. could she survive a spread of 4 torpedoes blowing up underneath her? Her broad flat double hull near the keel seems to be her weakest point in the grand scheme of things, a hold over from the days where her only threat was another battleship.

I guess to put it another way... was Vanguards keel unprotected against modern weapons? Proof abounds that submarines were capable of breaching destroyer screens, or was this something that would be more of a measure of damage control effectiveness saving the ship?
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Re: Battleship Vanguard Armor

Postby Steve Crandell » Wed Jun 11, 2014 3:17 am

steffen19k wrote:My question was more about the survivability of Vanguards structure against the weapons. could she survive a spread of 4 torpedoes blowing up underneath her? Her broad flat double hull near the keel seems to be her weakest point in the grand scheme of things, a hold over from the days where her only threat was another battleship.

I guess to put it another way... was Vanguards keel unprotected against modern weapons? Proof abounds that submarines were capable of breaching destroyer screens, or was this something that would be more of a measure of damage control effectiveness saving the ship?


I don't think we know the answer to that question. I've seen people on other forums claiming that ONE mark48 ADCAP torpedo would sink or at least cripple a Nimitz class CVN. Personally I doubt that, but I sure can't be certain of much of anything related to modern weapons and the protection of ships against them. It is certainly true that a large warhead of modern composition exploding under a ship has the potential to do devastating damage. The shock alone would potentially effect every system on the ship. A torpedo hitting the side of a ship has much of the explosive force released to the air above. Not so much for one going off under the ship.

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Re: Battleship Vanguard Armor

Postby alecsandros » Wed Jun 11, 2014 5:35 am

steffen19k wrote:My question was more about the survivability of Vanguards structure against the weapons. could she survive a spread of 4 torpedoes blowing up underneath her? Her broad flat double hull near the keel seems to be her weakest point in the grand scheme of things, a hold over from the days where her only threat was another battleship.

I guess to put it another way... was Vanguards keel unprotected against modern weapons? Proof abounds that submarines were capable of breaching destroyer screens, or was this something that would be more of a measure of damage control effectiveness saving the ship?

What do you mean by "underneath her" ? Torpedoes that come up vertically and hit the ship exactly at her maximum draft ?

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Re: Battleship Vanguard Armor

Postby Dave Saxton » Fri Jun 13, 2014 2:44 pm

alecsandros wrote:What do you mean by "underneath her" ? Torpedoes that come up vertically and hit the ship exactly at her maximum draft ?



The most devastating torpedoes are those designed to pass beneath the target and explode some meters below the keel triggered by the magnetic field. In addition to the shock wave, a giant bubble is created and the great mass of the target ship is no longer supported by sea water. This breaks the back of the target ship. There's really not much in terms of torpedo defense system design that can counter this. I doubt that Vanguard could survive this kind of attack if it was more than one.

The Tirpitz is the only warship that I know of which survived very powerful mines (2,000 kilograms-4,400 lb- of Amtex high explosive) exploding some meters underneath it or almost directly underneath it. Part of this survival was the structural design of the armoured longitudinal bulkheads and the low positioned panzer deck. These structures formed it effect a giant H-beam over the entire length of the citadel that the rest of the ship was constructed around (See MA6).
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Re: Battleship Vanguard Armor

Postby Dave Saxton » Fri Jun 13, 2014 3:00 pm

tommy303 wrote: Large vessels like Vanguard normally had degaussing coils built in to them for protection against such weapons. These reduced the magnetic field around the vessel to below that which would activate the mine or torpedo pistol. Post war, however, magnetic pistols became even more efficient and utilized a system which would sense any change in the magnetic field, allowing even a degaussed vessel to be attacked; this led to a post war mini technology race in improved degaussing vs improved magnetic weapons.


When the British first started testing PPI radars, it was found that de-gaussing could not be used with PPI type CRTs. It would throw the PPI indicators completely out of whack. If the de-gaussing was switched on then it was a long, labor intensive process to restore the radars to functionality. It doesn't appear to have affected magnetrons to as great a degree as CRTs. This may have been why the Germans used electro magnets (adjustable gauss and switchable on/off) for magnetrons and deflection circuits of the Berlin PPI radar systems.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.


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