Schofield & Markham

[rebelatsea]

Schofield & Markham refused to change their rollers to produce 2" plate for CSS Mississippi, although they did so for the Yazoo monster and subsequent vessels elsewhere.

My question is: what sort of plate were they rolling at 1.25" thickness? Dave Brt will confirm i think that no southern railroads were using strap rail by 1861 /2.

My understanding is that "standard" boiler plate was 1" thick and rolled in sheets 4ft x 3 or 2ft as appropriate.

However if they were rolling boiler plate at 1.25" thickness, and this was what was supplied to the Tifts, it changes the protection and appearance of the Mississippi.

 

[Mark F. Jenkins]

1" seems pretty thick to me... Louis C. Hunter's Steamboats on the Western Rivers gives the "standard" thickness of the boiler iron (wrought iron) as 1/4". (p. 155) Continuing to look for more data...

ETA: According to one source (http://www.nationalboard.org/PrintPage.aspx?NewsPageID=668) the Sultana's boilers were

made out of charcoal hammered No. 1 iron, 17/48ths inch thick. I don't know how they measured that that closely. They were four feet in diameter, 18 feet long, had 24 five-inch flues.

Another source [talking about a different boat], dated 1860 (https://www.scientificamerican.com/article/cause-of-boiler-explosions/):

The boiler was 40 inches in diameter by 22 feet long, made in the cylindrical form, without flues or tubes. The body of the boiler was said to be of the first quality of iron, one-fourth of an inch in thickness, and the heads were made of " angle " or " gunnell iron," which was half an inch in thickness.

(Hunter does note that a French visitor in 1850 was horrified by the lack of safety standards in boilers made in the US; it could be that boiler thicknesses were usually greater in Europe.)

 

[DaveBrt]

Locomotive Texas had boiler thickness of 5/16".

 

[rebelatsea]

Thank you for the info so far, I hadn't realised iron boiler plates were so thin in the USA. I suppose I'm used to English / British practice. That prompt another question then, what was 1" thickness plate used for?

 

[USS ALASKA]

Sirs, some questions...

With @rebelatsea 's original question, I did some research as this being a subject I am completely unfamiliar with...

So, in 1858 the Atlanta Rolling Mill was constructed. Found a reference in Atlanta and Environs A Chronicle of Its People and Events, 1820s-1870s by Franklin M. Garrett that states...

...is the underlined correct? I thought all the plate for CSS Virginia came from Tredegar Iron Works. If this is not factual, then the point is moot. If the underlined is correct, then that would imply that the Atlanta Rolling Mill was rolling 2" plate or the Virginia had some 1" layers on her.

Found a reference in Civil War Naval Chronology 1861-1865 by Naval History Department about the CSS Mississippi that states...

...does this imply that the individual plates were of those thickness or that when completed, Mississippi was armored to those thicknesses regardless of how many layers it took? Or...is this passage incorrect?

By the way, in reading about these gents, I am finding accusations of latent Unionism and even sabotage...

...rumor or accurate?

Anyway, thanks for the help...

Cheers,
USS ALASKA

 

[DaveBrt]

Sirs, some questions...

With @rebelatsea 's original question, I did some research as this being a subject I am completely unfamiliar with...

So, in 1858 the Atlanta Rolling Mill was constructed. Found a reference in Atlanta and Environs A Chronicle of Its People and Events, 1820s-1870s by Franklin M. Garrett that states...

View attachment 458948

...is the underlined correct? I thought all the plate for CSS Virginia came from Tredegar Iron Works. If this is not factual, then the point is moot. If the underlined is correct, then that would imply that the Atlanta Rolling Mill was rolling 2" plate or the Virginia had some 1" layers on her.

Found a reference in Civil War Naval Chronology 1861-1865 by Naval History Department about the CSS Mississippi that states...

View attachment 458950

...does this imply that the individual plates were of those thickness or that when completed, Mississippi was armored to those thicknesses regardless of how many layers it took? Or...is this passage incorrect?

By the way, in reading about these gents, I am finding accusations of latent Unionism and even sabotage...

View attachment 458951

...rumor or accurate?

Anyway, thanks for the help...

Cheers,
USS ALASKA

At least one set of iron plates was shipped from Atlanta to Norfolk:

Atlanta Armor Shipping Impact

Plate size is not noted in the original data.

 

[rebelatsea]

The original conversion of Merrimac commenced before John M Brooke conducted his armour tests in September 1861 utilising 1" plate. The conversion did indeed have some 1" plates according to Brooke. However the tests proved that 1" plate gave insufficient protection and when Tredegar found a method of cold punching 2" plate, more tests were carried out on 2 x 2" pate backed by 24" oak and pine, which proved able to resist any shot and shell fired at it. Consequently CSS Virginia's casemate was protected accordingly. All the 2" iron came from Tredegar at Richmond. Brooke does not cite the source of the 1" plate.
CSS Mississipi was to be protected by 2 x 2" plate but as stated Schofield & Markham wouldn't produce anything thicker than 1.25" forcing Assistant Constructor Joseph Pearce to utilise 3 x 1.25" layers on her.
I rather suspect that S & M being a commercial establishment had established customers for their output and were not prepared to jeopardise (as they saw it) that income for what might prove to be a one off order.

 

[rebelatsea]

It is of some interest that when Brooke presented his armour test firings to Secretary Mallory, at the meeting were Nelson Tift, Ship builder John T Shirley, Naval Architect W.T.Smith ,Chief carpenters Joseph Pearce and James Meads who had constructed the targets, Lt Catesby Ap R Jones who tested the "Virginia" target John L Porter and other constructors who later became prominent were not there.
Amongst his findings Brooke stated that seagoing ironclads must have vertical sides. a complete change to his former opinions, a comment which may have influenced the initial plans of what became the Mississippi and Arkansas.

 

[Mark F. Jenkins]

Amongst his findings Brooke stated that seagoing ironclads must have vertical sides.

Interesting. Do you know if he meant vertical sides to the hull or to the casemate/superstructure?

 

[rebelatsea]

It isn't entirely clear. I assume he meant both hull and casemate, although a combination of Porter's / Pearce's knuckle and a vertical casemate could work I suppose, hadn't actually considered that.

 

[Mark F. Jenkins]

Whenever Brooke expresses his opinion on something I'm inclined to give it serious thought. (Unintended pun with "inclined;" perhaps my subconscious is playing games with me once again.)

 

[rebelatsea]

Mark, I wouldn't have spotted that, but I'm inclined to agree !

 

[Mark F. Jenkins]

It isn't entirely clear. I assume he meant both hull and casemate, although a combination of Porter's / Pearce's knuckle and a vertical casemate could work I suppose, hadn't actually considered that.

There seem to be three general possibilities... a vertical side for a certain distance underwater, continuing to a vertical/near-vertical side wall (allowing for a bit of tumble-home, but not a large amount); vertical underwater and inclined/significant tumble-home above water; and a shallow, noticeably inclined/curving hull cross section with a vertical above-water side. (That last one doesn't sound to me like it would be very good for stability, though I am definitely not a qualified ship designer.)

 

[rebelatsea]

Mark, The first of your suggestions resembles the Porter / Williamson 1862 plan for a seagoing ironclad gunboat. the second is a bit "French" of 20 years later, and the last one describes the small French floating batteries for the far east - almost but not quite contemporary with the CSN, they weren't seagoing, but riverine.

 

[Mark F. Jenkins]

the second is a bit "French" of 20 years later,

That's actually the image that occurred to me (that and the armored cruiser USS Brooklyn). I know just barely enough about things like metacentric height to know that I have only a very rough idea of how these things work in the real world, though!

 

[rebelatsea]

The problem with getting into things like metacentric height is that every ocean and most major river systems in the world have different salinity and so you have to decide what and where you need your vessel to go. that's before we start thinking about depth of water, wave length, height and period. Such factors weren't yet properly understood in relation to steam ships in our era.