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Armour plating

Armour plating

Armour plating

Hi everyone,
I have been reading about WW1 and 2 battleships and the thickness of their armour plating. I am curious how such thick plates were joined and attached to the ship's frame. Even with modern welding methods I don't imagine plates 12" thick could be welded very easily plus the plates were heat treated to give a high surface hardness so I would have thought that would preclude welding even if it was available to all the shipyards concerned, (non in WW1).
If the plates were butted together without edge connections they would still need attaching to the structure and I wonder how it was done?

RE: Armour plating

I'd guess that several thinner sheets were layered to achieve the final thickness.

That's how wooden ships were build, and ship builders are a traditional lot. They might have changed material from wood to steel, but they probably didn't change the construction method all that much.

As for joining and attaching - rivets.

RE: Armour plating

I used to have some old literature describing armour plating for battleships.
And one of the descriptions was " Krupp cemented amour plate" showing the damage done by a naval shell.
The sample plate had rivet holes along the edge of the plate, suggesting that maybe that was the attachment method.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

RE: Armour plating

Thanks for your interest gentlemen. I did not realise that arc welding had such a long history but I don't think that it was widely used much before the late 1930's and did not became widespread until after WW2. There was plenty of hot riveting on UK steam engines right up to the last BR steam engine, the Evening Star, built in 1960, which had a riveted boiler. When I worked at International Combustion in the early 70's they welded power station boiler drums up to 150mm thick. As an aside I remember seeing boiler drum drawings for WW2 war ships with forged header and mud drums that were bent to follow the line of the ship's hull. I have never actually worked anywhere that still used traditional riveting but I would have though very long rivets would have been too elastic but then I am no stress man.
I will ask our Welding Engineers at work how thick you can go with welded joints although I suppose they don't make plate thicker than you can join as a general rule.
One thing is for certain I am dam glad I have never had to sit in a floating steel box whilst someone hurled 18" shells at me - it must have been horrific, especially when fragments spalled off the inside face of the armour after a hit.

RE: Armour plating

Greg might know, I recall him being a little bit of a battleship buff.

I did find this link which talks about bolting though I'm not sure if it's typical.


This one talks about bolting & welding.


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RE: Armour plating

The link to the USS Washington was very interesting. It looks as though the plates were scarf jointed and on that ship anyway attached with stud welded bolts. That just begs the question of how it was done before welding?
The boys on the Bismark forum seem very knowledgeable so perhaps I should place a post their but I am still very interested in anyone's input on this site.
I had an Uncle who served on the Hood but unfortunately he passed away some years ago or I could have asked him.
Did anyone build Airfix models of all those famous warship from the past? I think they cost about 10 bob which was quite expensive in the 1960's

RE: Armour plating

Certainly tank armor was riveted well into WWII on some designs. Obviously not quite as thick as battle ship main belt but several inches on Matildas & early Churchills front armor (later 'heavy' Churchills were welded if memory serves).

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RE: Armour plating

I'll look out some details for British ships tonight, but from memory during WW1 the armour was rolled to shape and then bolted or riveted to the structure underneath. By WW2 welding was used at some shipyards by some countries. Back when ship designs were interesting bolting was always used, often with a wooden backing. Even a non penetrating hit could cause mass carnage as the severed bolt heads would fly around like shrapnel.

Multiple sheets with no airgap weren't used by the major powers that I know of from 1900 onwards, and generally one thick plate is more useful than two thin ones with an airgap. There are advantages in using two thin ones, the decision is not completely one sided.


Greg Locock

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RE: Armour plating

Here ya go, Newton 1941 Practical Construction of Warships

"The armour is held to the plating behind by large hexagonal headed bolts tapped into the armour and bearing on tapered steel washers and grommets. The heads... are fitted with locking plates... and are enclosed by pressed steel covers..."

So that's it for the RN up til WW2.

Yamato used welded armor at least in part and this was not viewed as an unqualified success. I do not know if the armor in this case would have formed the watertight skin as well, I suspect not.

Breyer p36 has a simple chart showing typical designs 1860-1902, bolts used throughout.


Greg Locock

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RE: Armour plating

Hi Greg,
Thanks for taking the trouble to reply. I assume that the armour was basically just hung on the outside of the hull and did not contribute directly to the water-tightness of the ship. I wonder how they combated rust between the hull and in the plate joints?
I have Googled for Newton's 1941 Practical Construction of Warships and as there seems to be lots of copies available at reasonable prices I will order myself a copy.
Thinking back to my youth there were quite a few Navy men I could have asked but they are sadly long gone.

Best regards,


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