TDS of HMS Hood

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wmh829386
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TDS of HMS Hood

Post by wmh829386 »

It was often clamined that Hood had the best TDS of any RN ships when she was launched with a significant buldge that contains steel tubes to absorb the energy of the explosion.

But from a number of plans I cound find there is no bulkhead behind the thick bulkhead of double layer of 30lbs HT that joints directly with the lower edge of the belt and slope along the forward boiler room.

https://www.pinterest.com/pin/848084173563685206/
http://www.navweaps.com/index_inro/no21 ... Layout.jpg

Even the mid and aft engine rooms are not much better with only a thin narrow bulkheads, which some holds feedwater.

It begs the question on whether the thick bulkhead could be expected to remain mostly water tight without any backing (such as oil tanks along boiler rooms)? Further more, isn't the designe of joining the stiff belt with torpedo bulkhead is a sure way to cause rupture of the torpedo bulkhead under shell fire?

Does that not introduce a weakspot in which a single torpedo hitting between forward and middle engine room could disable three shafts? Or is there some justification that led designers to believe that such arrangements is not a weakness?
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marcelo_malara
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Re: TDS of HMS Hood

Post by marcelo_malara »

Hi. May be this helps.

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wmh829386
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Re: TDS of HMS Hood

Post by wmh829386 »

I have seen that before. This is a cross-section of the boiler room where there is an oil tank behind the torpedo bulkhead (14). But in the case of the forward engine room, there is no longitudinal bulkhead after the torpedo bulkhead, which is also supporting the belt at the same time. I find that arrangement a bit odd and wonder if that is an liability.
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Re: TDS of HMS Hood

Post by marcelo_malara »

Yes, you are right, in the engine rooms there are no side tanks, you have a void (9) followed by the compartment filled with the hollow cylinders. I would say that the side tanks are not part of the TDS:



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Re: TDS of HMS Hood

Post by Bill Jurens »

While the discussion is interesting, I'd caution correspondents to exercise caution in posting extensive scans, etc. of specifically copyrighted material, especially if the source is not mentioned. In this case the material is clearly from John Roberts' "Anatomy of the Ship -- Hood. One scan may be reasonably considered 'fair use', but multiple scans are tending towards that 'grey area'. In any case, it's always a good idea to post the source of the scanned material as well.

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marcelo_malara
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Re: TDS of HMS Hood

Post by marcelo_malara »

Yes, Bill, you are right, it is from the excellent AOTS volume, sorry for not clarifying this. I understand the copyright issue, anyway, I must say, I own physical copies of all books I speak about, to the extent that I recently bought Jomini´s The art of war, even having it on pdf as it is in the public domain.
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Re: TDS of HMS Hood

Post by wmh829386 »

Just a quick look at the damages in Jutland shows plenty of case where not penetrating hit on belt armour causes the hull plating behind to split. In the case of Hood's engine room, doesn't that implies a single non-penetrating hit on the belt along the forward engine room would very likely to cause it to flood?

It seems like a very questionable design or is there something else to it?
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Re: TDS of HMS Hood

Post by Steve Crandell »

wmh829386 wrote: Fri Oct 08, 2021 2:12 am Just a quick look at the damages in Jutland shows plenty of case where not penetrating hit on belt armour causes the hull plating behind to split. In the case of Hood's engine room, doesn't that implies a single non-penetrating hit on the belt along the forward engine room would very likely to cause it to flood?

It seems like a very questionable design or is there something else to it?
It doesn't appear to me that the engine rooms are adjacent to the belt armor.
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Re: TDS of HMS Hood

Post by marcelo_malara »

If there is an impact in the lower belt, that would allow flooding, most probably the water would go to the void 9 over the armoured deck. For an impact below the belt, the shell would travel below water for a while, which would deviate it because of the water density (look for the Japanese diving shell needing a special design to do this).

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Re: TDS of HMS Hood

Post by wmh829386 »

But along the engine room, the lower belt shares the same continues hull plating, if the void 9 is breeched through buckling of the lower belt, isn't it likely that the joint that combines three structual member (Belt, torpedo bulkhead, and armor deck) would be damaged and not remain water tight?
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Re: TDS of HMS Hood

Post by wmh829386 »

To be clear, I am wondering if this joint that might be damaged by shell hit on the lower belt.
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Re: TDS of HMS Hood

Post by marcelo_malara »

Yes, I understand your reasoning.

I can find three variations in this type of TDS:

1-the Hood system, armoured belt and torpedo bulkhead shares the same hull plating, and a blister is built outboard of this. Internally to the torpedo bulkhead there is an oil tank to some extension, exists in the boiler rooms but not in the machinery room.

2-the Warspite system, detailed below (from AOTS), same as Hood but internal tanks extend around all machinery rooms.

3-Bismarck (from AOTS too, farther down). Armoured belt is built on the hull plating, there is no blister, so torpedo bulkhead is internal, there is no connection between belt and torpedo bulkhead.

From your point of view, Bismarck´s is best, for a shell to impact the torpedo bulkhead it has to travel quiet a path underwater (anyway I think it happened in her short career). Second best would be Warspite. Why Hood´s oil tanks were not continued to the machinery rooms? I don´t know. I suspect two things:

-the machinery of Hood is quiet powerful and needs more space, forbidding the installation of side tanks near them
-Hood was a long ship, may be the tanks around the boilers were enough for her design range


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Re: TDS of HMS Hood

Post by wmh829386 »

The TDS of QEs are decent for rebuilt 1914 battleships, but that's about it. (Barham was topedo twice. First around forward turret group and flooded the Magazines, the second time sunk with heavy loses when three torps hit her at once. Malaya was torpedo once with minor damage around boiler room), the performance is not too bad but not great either. Basically the torpeodo bulkhead is rather thick 2" , but hampered by lack of depth and poor isolation of its structures near the ends of the ship.

Bismarck just have tons of depth with a rather traditional approach, not really much to fault it on its own.

Most BBs has armor belt and torpedo bulkhead mounted on seperate structures, the only exception I can think of are US fast battleship after North Carolinas (Alabamas & Iowas?), Yamato, and Hood.

But I have NEVER seen a design where the belt is mounted directly on the bulkhead of engineering spaces like Hood does. The main issue I am raising is about non-penetrating hit on the main belt in the highlighted area and also torpedo hits around the engine room.

It troubles me even more because it was claimed that the TDS of Hood was better than any previous RN battleships. :stubborn:
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Re: TDS of HMS Hood

Post by Steve Crandell »

The USN's Montana class would have gone back to the scheme used on North Carolina, with the addition of a separate internal belt intended to stop diving shells. It was separate from the torpedo bulkhead, though.
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Re: TDS of HMS Hood

Post by marcelo_malara »

There was no space aside the turbines, specially in the front engine room, look at the machinery spaces (from AOTS):

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