CSS Mobile Ironclad

Bil R

Private
Joined
Mar 23, 2011
Location
Massachusetts
Hello Gentlemen,

George and John those are excellent posts. The Mobile was the first of the 'lesser known' Confederate ironclads that I researched in detail. At the time I was in Philadelphia which gave me extended access to the various archives and collections there. The resulting file of primary source information on this vessel now extends to four pages and a little over 4,200 words. And I have not yet included George's details about the CoE contract above (most interesting), various 'Vessel Papers' citations, and the Waterman account of her withdrawal from Berwick Bay up the Atchafalaya. First, some essential details:

Mobile - Class 1 vessel

Designer: William Cramp, Stephen Flanagan
Builder: William H. Cramp & Son
Location: Philadelphia (Kensington), PA
Keel Laid: 1 August 1860, Hull No. 92
Launched: October 1860
Registry & Enrollment, Commissioned, Merchant: 8 December 1860
for S. & J. Flanagan, intended for Mobile, New Orleans and Havana trade

Acquisition & Cost: Seized 23 May 1861 as prize and sold private,
purchased 14 August 1861 by CSN, $5,000
Gunboat Conversion: August through December 1861
Designer: Lieut. Shepperd, CSN, John Roy
Location: Berwick Bay, off Brashear City (Morgan City), LA
Ironclad Conversion: October 1862 through May 1863, incomplete
Designer: Lieut. I. N. Brown, CSN, Weldon & McFarland, Acting CSN
Builder: Confederate States Navy
Location: Below Yazoo City, MS
Commissioned, Naval: 1 December 1861, decommissioned 1 August 1862
Fate: Burned and sunk 23 May 1863 below Yazoo City, MS

Rate: Blockade runner, gunboat, wooden protected, ironclad
Service: Intended for Mississippi River and Gulf coastal areas
Specifications:
Hull:
Tonnage- 282 7/95ths tons, 450 tons gross
Length- 139 ft. 6 in. deck, 145 ft. oa
Beam- 28 ft.
Depth of Hold- 7 ft. 9 in.
Draft- 6 ft. 6 in. load line
7 ft. 6 in. deep

Notes: Wooden hull, built of white oak with iron fastenings and
copper bottom, billet head, round stern, one deck

Masts & Rig:
Two masts, topsail schooner rig

Notes: Reported to have three masts in February 1862 which may
have been fitted during her gunboat conversion. All masts and rig
removed prior to her withdrawal from Berwick Bay.

Engines:
Built by Reanie, Neafie & Co. (Penn Works), Philadelphia, PA,
Engine No. 311:
1 vertical, direct acting engine, 32 in. diameter, 28 in. stroke

Boilers:
Built by same:
1 low pressure, return flue, tubular boiler 12 ft. 6 in. long by
7 ft. 7 in. wide, 7 ft. 7 in. high, firebox 6 ft. long by 8 ft. wide,
2 furnaces

Propulsion:
1 screw, 8 ft. diameter, four blades, 4 ft. 3 in. tip, 18 ft. pitch,
angled 62 degrees, hub 20 in. long, weighs 3,487 lbs.

Notes: Engine 100 hp, inverted cylinder, jet condensing, generates
84 rpm at 30 psi, shafts made of wrought iron, bedplate 8 ft. 5 in.
by 4 ft. 4 in., air pump fitted with two force pumps, propeller shaft
24 ft. 5 in. from hub to cylinder center, from cylinder center to
firebox face 9 ft. 10 in. or 34 ft. 3 in. from hub to firebox face, est.
one raked chimney 4 ft. diameter by 20 ft. high above firebox

Protection:
Machinery spaces, gunboat: Boiler lowered in hull, timber bulk-
head built around machinery consisted of 12 in. square beams covered
in one layer of railroad iron
Ironclad conversion: Reported that the casemate construction was
complete and awaiting iron plating or rail when burned; vertical
sides without knuckle conforming to hull shape like Arkansas; ends
angled at 35 degrees and to be armed with two pivot guns and two
broadside guns

Armament:
Fitted with: one 8 in. shell gun forward, one 32 pdr. rifle aft, and
two small 32 pdr smoothbores

Boats & Fittings:
1 launch, 1 yawl boat

Officers & Crew:
Lieut. Shepperd, CSN, about 40 men, later transferred to man
Arkansas

General Comments - The Mobile was built as a coastal passenger freight vessel intended for operations in the Gulf of Mexico. She was also provided with additional equipment that would allow her to work as a towboat or 'work' boat on the lower Mississippi. This is alluded to in the following description from the 'Philadelphia Inquirer': ..She has a donkey engine on deck, with supplementary boiler for hoisting cargo, with patent steam pump attached, with a capacity for throwing 800 gallons per minute, which can be used for extinguishing fires, pumping out vessels or wrecking purposes. She is also provided with a large and efficient double-acting force pump, situated at the forward part of the boat, which can also be used for extinguishing fires or pumping out the vessel. She is well fitted with anchors and chains and everything else requisite for a sea-going vessel... This was also noted in the 'New Orleans Daily True Delta' upon arrival: ...The Mobile, though intended to ply between this city and New Orleans, is capable of being readily employed for other purposes, a valuable part of her machinery being an apparatus for pumping out sunken ships... As George described above, I was not aware that she had actually been contracted by the Corps of Engineers for work at the Southwest Pass. After she was seized, sold and re-registered as a Confederate merchant there are two documented runs into New Orleans, one into Galveston and one into Mobile.

Regarding her gunboat conversion she was fitted with four guns as per John Roy's diary and Mallory's report. Besides lowering the boiler and protecting the machinery with an ironed wooden bulwark, she received an additional sheathing of the main deck with pine plank from aft her fore hatch to the main mast. Shot racks were placed below, bulkheads were fitted below to create shell rooms, store rooms, a head, a magazine and officer berths. In addition the rails were cut down in 'wake of her forward and aft pivot guns'. I would not be surprised if she was fitted with a third, light mizzen mast while in Berwick Bay. It would enhance her speed, assist in handling and give the impression from a distance, that she was a larger vessel than she was. Semmes had done this already converting the 2-masted Habana into the 3-masted Sumter. The cutdown rails would certainly give the reported (1 February 1862) appearance of a 'long, low steamer'. According to Waterman's account, if I recall correctly, Lovell ordered the withdrawal of all useful vessels from Berwick Bay to Vicksburg upon the initial bombardment of the lower forts. He gives a rather colorful account of the difficulties encountered in navigating a flooded Atchafalaya covered in thick overgrowth. They could barely keep their funnels clear, much less any additional rigging. It took them four days to make the Mississippi north of New Orleans. The A.B. Segar had been left behind, but the group included the Mobile, St. Marys (f. Herron, built 1862), and mailboat St. Marys (built 1858, l. Alexandria). Upon arrival at Yazoo City, she was employed as a guard boat until her crew was tapped to help man the Arkansas.

After being decommissioned, Brown selected her for conversion into an ironclad. She was relatively new, had good machinery already protected, was shallow drafted, screw propelled, armed and would need minimal modifications. Lacking a drydock, or even a flattened beach to careen a vessel, Brown probably would have extended a vertical casemate directly up from her hull sides like the Arkansas. She has too narrow to have angled sides. There is a voucher to pay for a Marsilly carriage in 1863 suggesting at least two broadside guns. I would imagine the pivot end guns would have fired through three ports and her funnel would have remained aft as originally placed. Her main deck after conversion would have been about a foot above waterline and partial bulwarks or railings would have remained fore and aft. She would have been a smaller version of the Arkansas.

References - The details discussed above come from the ORN, the NA (M346, M909, RG41, RG45, RG109) various Philadelphia and New Orleans newspapers, Cramp Collection at the Independence Seaport Museum and the Franklin Institute Special Collections. The last mentioned possessed a Cramp Table of Offsets that begins with the aft half of hull 107 - Bahia Honda, built in 1862. That vessel was built for a Cuban merchant for similar trade as the Mobile and was slightly larger. Comparing her lines to later built Cramp steamships shows a remarkable similarity in shape and form. I have come to believe that naval architects are like artists and have a consistent 'style or appearance' to their vessels, almost to the point that one can identify a builder by carefully looking at an image. If you want to know the Mobile's hull form look at the Bahia Honda, Zabiaka and other Cramp vessels of the era. They had consistent round sterns, narrow sharp bows and a sheer that descends to about a third of the hull and then begins to rise again. I believe that Table of Offsets book has now joined the other Cramp's material at the Independence Seaport Museum. The Reanie, Neafie & Co. workshop book is located in the Mariner's Museum.
I hope this is helpful.

All the best,
Bil
 

georgew

Sergeant
Joined
Oct 1, 2010
Location
southern california
Bil,

That is brilliant, thank you for all the information. Seems I shall have to modify the plans slightly for the second edition of my book.
Hi John, since we're talking about I.N. Brown re the conversion you wonder if he would have ironed her like the Arkansas? ie run strap rail horizontally on the sides of the casemate and perhaps two layers (laminate) on the front and rear casemate panels. The boilers and engine were already "hardened" internally from her gunboat conversion. perhaps a little RDS treatment to the bow in lieu of a formal ram?
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
Hi George, Mobile wasn't a big vessel so I imagine it would be no more than 2" iron at best, perhaps with 4" on the casemate ends. Indeed a degree of bow strengthening seems a good idea. Reading Bil's description of the conversion reminded me that she would have resembled James Mead's conversion of the Abrahams Tobacco Company vessel to produce CSS Brandywine. I wonder where (now Constructor) Meads was, as he had left Richmond. Maybe just a coincidence. Thinking further on that, John Roy was involved producing gun carriages, Where was E M. Ivens, as he had not returned to Tredegar either.
 

georgew

Sergeant
Joined
Oct 1, 2010
Location
southern california
Hi George, Mobile wasn't a big vessel so I imagine it would be no more than 2" iron at best, perhaps with 4" on the casemate ends. Indeed a degree of bow strengthening seems a good idea. Reading Bil's description of the conversion reminded me that she would have resembled James Mead's conversion of the Abrahams Tobacco Company vessel to produce CSS Brandywine. I wonder where (now Constructor) Meads was, as he had left Richmond. Maybe just a coincidence. Thinking further on that, John Roy was involved producing gun carriages, Where was E M. Ivens, as he had not returned to Tredegar either.
Hi John. Meads ended up at Little Rock and later appeared at Schreveport. No idea re Ivens. Thanks for clearing up who converted the Brandywine. I have a suspicion that Roy was doing more than gun carriages. You wonder who supervised the iron reworking from the tinclad Wave at Shreveport allegedly used on Shreveport/Houston submarine projects? In the case of Mobile, could centerline guns on pivots have been retained so that she would have the same broadside firepower with only 3 guns versus the four gun layout some claimed? I ask because in theory in the 3-gun configuration centerline the broadside guns could have been heavier than the smaller broadside 32's mentioned. Just where these guns would come from is another question. If the guns were available, 3 rifled 32"s would have been preferable, simplifying the ordnance stores. You also wonder about the layout of magazines for the Mobile. There would have been two due to the boilers being dropped into the hold. Brown stripped out most of the "high end" firepower up the Yazoo when he turned the Arkansas into the "box of guns". Heavier iron on the forward and aft panels on the casemate would have made a lot of sense on Mobile if the iron was available. With the Arkansas Brown was willing to use sheet iron on the stern above the rudder and allegedly half-inch on the casemate roof.
 

Crossroads

Cadet
Joined
Jan 2, 2021
Bil,

That is brilliant, thank you for all the information. Seems I shall have to modify the plans slightly for the second edition of my book.
rebelatsea

If you are going to revise your book, may I suggest correcting the following erroneous statement found on page 186 (C.S.S. Mobile)


“On February 27, 1862, Secretary Mallory reported that two ironclad centrewheel steam gunboats, with iron prows as rams, were under construction at New Orleans under the supervision of Lt. Issac Newton Brown.”

The actual source of this above misinterpreted document is:

S. R, Mallory to Jefferson Davis, February 27, 1862

O.R. Navy Series 2 Volume 2 pages 149 – 154.



On page 150 Mallory does make the following statement:

“Two ironclad steam gunboats, with iron prows as rams, are in course of construction at New Orleans, to carry four guns each and it is expected will be completed in 50 days.”

However, Lt. Brown’s name is not mentioned in connection with these New Orleans vessels and in fact the only time he is mentioned is on the very last page of the message (Page 154) when Mallory states:

“On the 24th of December last Congress appropriated $500,000 for the construction of gunboats on the Cumberland and Tennessee Rivers, and on the following day I sent an energetic and reliable naval officer, Lieutenant Isaac N. Brown, of Mississippi, to Nashville, with full authority and instructions to purchase and arm steamers and convert them into gunboats with all possible dispatch.”

The statement on page 186 can also be proven to be incorrect because following the abandonment of the unfinished ironclad C.S.S. Eastport, and the Confederate evacuation of Nashville, Lt. Brown did not travel immediately to New Orleans and in fact did not arrive in New Orleans until early March, definitely not in February.

If you have any evidence that the above referred to statement is in fact correct, please post it.
As historians, we only want the facts, and if I am mistaken I will admit it.
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
Crossroads,
The revision has indeed started although if it takes 30 years it won't be me publishing ! The book is not perfect nor does it pretend to be. Your corrections are welcome. Indeed the first one re Brown's connection to the NO gunboats has answered a question which many people have asked.
There is another about these two NO gunboats to which you may have the answer. I followed my friend Bob Holcombe in showing them as "Muscogee" type centre wheel ironclads, but they cannot be. They predate Porter's plan, and have only four guns.
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
Hi John. Meads ended up at Little Rock and later appeared at Schreveport. No idea re Ivens. Thanks for clearing up who converted the Brandywine. I have a suspicion that Roy was doing more than gun carriages. You wonder who supervised the iron reworking from the tinclad Wave at Shreveport allegedly used on Shreveport/Houston submarine projects? In the case of Mobile, could centerline guns on pivots have been retained so that she would have the same broadside firepower with only 3 guns versus the four gun layout some claimed? I ask because in theory in the 3-gun configuration centerline the broadside guns could have been heavier than the smaller broadside 32's mentioned. Just where these guns would come from is another question. If the guns were available, 3 rifled 32"s would have been preferable, simplifying the ordnance stores. You also wonder about the layout of magazines for the Mobile. There would have been two due to the boilers being dropped into the hold. Brown stripped out most of the "high end" firepower up the Yazoo when he turned the Arkansas into the "box of guns". Heavier iron on the forward and aft panels on the casemate would have made a lot of sense on Mobile if the iron was available. With the Arkansas Brown was willing to use sheet iron on the stern above the rudder and allegedly half-inch on the casemate roof.
George, John Roy had invented a turntable mount intended to replace pivot carriages, seen on CSS J A Cotten, so indeed a 3 gun layout for the conversion could have been possible. Brown had the guns from her as a wooden gunboat available, so had a limited choice. Using the 1 - 32pdr MLR (chase gun fwd) and 2 - 32pdr SB would have been logical - and sensible, given that the vessel, although cut down had the weight of a casemate and armour added.
 

georgew

Sergeant
Joined
Oct 1, 2010
Location
southern california
CSS Mobile as an ironclad
Class: ironclad gunboat
Type: Eastport.
Dimensions: 150ft OA x 28ft EX x 7.5ft D, 450tons. One screw, speed 8 knots estimated
Guns: 1 -8” MLR, 1 -32pd MLR, 1 -32pdr SB
Armour: probably 2” over 12” timber on the casemate.
Design; I. N. Brown. Builder: I. N. Brown, Yazoo City Navy Yard Conversion started late 1862, not completed Ordered to Yazoo City to be converted to a two- gun casemate ironclad. However, it is more likely that I. N. Brown would have converted her to his Eastport plan for speed and ease of construction and to use the materials at hand. Burned to prevent capture 21 May 1863.

Conjectural final appearance. Original plan by the author .
View attachment 390505
Hi John. If your drawings of the gunboat and ironclad conversions are any where near correct I wonder why they wouldn't incorporate something to protect the rudder post? I also wonder if that graceful curve we see on the broadside views reflects the actual deck line or a rail line? I think you have automatically compensated for these lines by showing higher gun ports implying an elevated ordnance deck. This would have an effect on the chaser tubes, possibly requiring a different shaped port to allow extra lowering of the gun tube for firing on closer targets, especially in a riverine context?
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
Hi George, There may have been rudder protection in the gunboat - but it's not mentioned anywhere. In the "ironclad" Brown might have had a sheet of iron tacked on in addition to the extra layer of timber over the deck. I think the floor of the casemate would have been made level from fore to aft for practical reasons of moving heavy guns about, but again unproven. I've given it Arkansas style "frigate" ports. The fore and aft chasers depression would be limited by the top of the stem and sternpost even with the hull cut down to deck level.
 

Ptarmigan

Private
Joined
Jul 21, 2013
I think that so far we are looking at this wrongly so am putting some ideas forward for your consideration. The key issue here is the fact that Mobile began her conversion into an "Ironclad" at Brashear City LA and that she had the remarkably shallow draft of only seven feet nine inches which is pretty small by Civil War naval standards and it should be the prime consideration when you consider what she looked like. We know this is likely because she managed to navigate the Atchafalaya river (probably without her armour) which is no mean feat for even a shallow draft riverboat as this river was very difficult to navigate. First of all, lots of ships had schooner rigs, Anglo American had one but this didn't mean she was a sailing ship, what I think we are looking at here is a vessel similar to the US navy tug Pinta (pictures on on pages 112 and 184 of Silverstone) with her bulwarks cut down to her main deck and a small central casemate erected to protect her machinery amidships. The curious thing is that the J A Cotton was also converted into an "ironclad" at Brashear city and was said to have an armoured casemate but it did not contain any guns as they were mounted on the foredeck as the two pictures of her indicate with an ironclad shield in the shape of a cowcatcher protecting her machinery. I think that the Mobile's protection was also likely for her machinery only like the J A Cotton and the Hart, all were conceived in the same location. I can see you might want to have this vessel look like another Arkansas but consider this, one was converted in Louisiana using similar methods used to convert RDF and Hollins's vessels at New Orleans, the other built keel up in Tennessee. Personally I see this vessel as more of a larger version of Maurepas or Little Rebel with deck mounted guns and a small 2 inch thick casemate protecting her machinery amidships and not a true ironclad like Arkansas.
 

Biscoitos

Private
Joined
May 14, 2020
I think that so far we are looking at this wrongly so am putting some ideas forward for your consideration. The key issue here is the fact that Mobile began her conversion into an "Ironclad" at Brashear City LA and that she had the remarkably shallow draft of only seven feet nine inches which is pretty small by Civil War naval standards and it should be the prime consideration when you consider what she looked like. We know this is likely because she managed to navigate the Atchafalaya river (probably without her armour) which is no mean feat for even a shallow draft riverboat as this river was very difficult to navigate. First of all, lots of ships had schooner rigs, Anglo American had one but this didn't mean she was a sailing ship, what I think we are looking at here is a vessel similar to the US navy tug Pinta (pictures on on pages 112 and 184 of Silverstone) with her bulwarks cut down to her main deck and a small central casemate erected to protect her machinery amidships. The curious thing is that the J A Cotton was also converted into an "ironclad" at Brashear city and was said to have an armoured casemate but it did not contain any guns as they were mounted on the foredeck as the two pictures of her indicate with an ironclad shield in the shape of a cowcatcher protecting her machinery. I think that the Mobile's protection was also likely for her machinery only like the J A Cotton and the Hart, all were conceived in the same location. I can see you might want to have this vessel look like another Arkansas but consider this, one was converted in Louisiana using similar methods used to convert RDF and Hollins's vessels at New Orleans, the other built keel up in Tennessee. Personally I see this vessel as more of a larger version of Maurepas or Little Rebel with deck mounted guns and a small 2 inch thick casemate protecting her machinery amidships and not a true ironclad like Arkansas.
Thank you so much for bringing a new and different perspective to this thread!
Your familiarity with the Mobile's status in Louisianais is most impressive.
Your statements are certainly worthy of consideration.
I would love to hear more from you on this subject.
Aren't you the fellow with the detailed dioramas of Vicksburg and Memphis?
 

Ptarmigan

Private
Joined
Jul 21, 2013
Aren't you the fellow with the detailed dioramas of Vicksburg and Memphis?

Yes, I have to admit that this is true, Covid lockdown will do strange things to you but I'm okay now. I love the research by the way, I use it a lot, if only I had access to such good sources here in the UK.
 
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georgew

Sergeant
Joined
Oct 1, 2010
Location
southern california
I think that so far we are looking at this wrongly so am putting some ideas forward for your consideration. The key issue here is the fact that Mobile began her conversion into an "Ironclad" at Brashear City LA and that she had the remarkably shallow draft of only seven feet nine inches which is pretty small by Civil War naval standards and it should be the prime consideration when you consider what she looked like. We know this is likely because she managed to navigate the Atchafalaya river (probably without her armour) which is no mean feat for even a shallow draft riverboat as this river was very difficult to navigate. First of all, lots of ships had schooner rigs, Anglo American had one but this didn't mean she was a sailing ship, what I think we are looking at here is a vessel similar to the US navy tug Pinta (pictures on on pages 112 and 184 of Silverstone) with her bulwarks cut down to her main deck and a small central casemate erected to protect her machinery amidships. The curious thing is that the J A Cotton was also converted into an "ironclad" at Brashear city and was said to have an armoured casemate but it did not contain any guns as they were mounted on the foredeck as the two pictures of her indicate with an ironclad shield in the shape of a cowcatcher protecting her machinery. I think that the Mobile's protection was also likely for her machinery only like the J A Cotton and the Hart, all were conceived in the same location. I can see you might want to have this vessel look like another Arkansas but consider this, one was converted in Louisiana using similar methods used to convert RDF and Hollins's vessels at New Orleans, the other built keel up in Tennessee. Personally I see this vessel as more of a larger version of Maurepas or Little Rebel with deck mounted guns and a small 2 inch thick casemate protecting her machinery amidships and not a true ironclad like Arkansas.
Taking your idea in hand, we know that Mobile's boiler was lowered at Brashear in her original conversion. Assuming that the upper portion of the dropped boiler didn't protrude above the main deck, then a short casemate might not have been necessary if you leave exposed guns on the deck, or build timber/iron gun emplacements with exposed upper areas. As Mobile was intended for riverine employment, a variety of specialized deck layouts become possible. It really depends on space available and what premium you put on protecting the gun crew(s), especially overhead protection against air bursts which might have been satisfied with boiler iron.
 

georgew

Sergeant
Joined
Oct 1, 2010
Location
southern california
George, John Roy had invented a turntable mount intended to replace pivot carriages, seen on CSS J A Cotten, so indeed a 3 gun layout for the conversion could have been possible. Brown had the guns from her as a wooden gunboat available, so had a limited choice. Using the 1 - 32pdr MLR (chase gun fwd) and 2 - 32pdr SB would have been logical - and sensible, given that the vessel, although cut down had the weight of a casemate and armour added.
Hi John. Roy's turntable mount is news to me. I've seen a Union sketch of the wreck of the Cotton and I don't recall seeing any sign of something like that on the forward deck. Do you have any idea of just how it was laid out or how wide in diameter?
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
George, I believe a sketch of the wreck which showed the turntable was posted as part of a thread on here on the Cotten. I thought i had printed a copy for my file on the ship but no. Entirely from memory the thing was made out of railroad rail on which the gun carriage wheels ran, it had a central pivot and flat spokes, looked a bit like a wagon wheel laid flat. Brooke adopted the turntable for his heavy ordnance and several ironclads including CSS Nashville, CSS Milledgeville were designed to mount them. The 11"SB for Palmetto State would have been on one had Beauregard not thieved it for the Charleston defences.
 

Ptarmigan

Private
Joined
Jul 21, 2013
The Mobile’s boiler was lowered into the hold similar to other Louisiana conversions such as the RDF vessels , however on this size of vessel it would still leave a proportion of the boiler above the waterline unprotected hence the need for an armoured casemate on these vessels. Mounting guns that were unprotected was common practice in Louisiana, even new built ships like Carondelet and Bienville had them as well as every vessel in the RDF, New Orleans ram fleet, the Louisiana State navy, Hollins’s flotilla and Lake Pontchartrain’s fleet. There are only five Confederate vessels that were converted into Ironclads in the whole war as far as I can recall and only one of these was on the Mississippi so this was not common practice, where as in the same region there were up to forty gunboats which had their machinery protected and their guns mounted upon an open deck.

A lot will depend on information that I do not have available to me as I am ignorant of the manufacturing facilities on the Yazoo. If it was that the region possessed a rolling mill that could turn out 2 inch strip iron and the iron was readily available then the conversion in mind would have been possible. I have calculated that such a vessel with a two inch casemate would have weighed close to 100 tons more when you take into account the weight of 71 tons of iron plus the timber backing and weight of the 4 guns etc. I am no Nautical engineer but I would say such a vessel with a 28 foot beam and a gross 450 ton displacement would be quite low to the water by then and perhaps not a little unhandy but this was par for the course for Confederate ironclads. It seems to me that as the concept of this "Ironclad" began in Louisiana then it would have followed their practice, that is not to say that it may have deviated from this while resting up on the Yazoo. Everything depends on the availability a local rolling mill and more importantly a surplus of railroad iron, if it wasn’t there then the armour would need to be overlapping railroad armour and then the weight of the iron alone would be excessive for a casemated ironclad on this displacement and beam. Another consideration that needs to be made is that by this stage of the war a two inch covering of iron was deemed inadequate and would be seen as a waste of resources especially as Arkansas did not have enough plate to cover the aft portion of her casmate when presumably it could have been taken from Mobile at this time. If it was that railroad iron was the only choice available then I calculate that a vertical box, fully protecting the boilers would weigh no more than 30 tons but of course the guns would be left unprotected on deck as was the usual practice in Louisiana for this type of conversion.
 
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Bil R

Private
Joined
Mar 23, 2011
Location
Massachusetts
Hello Gentlemen,

Those are excellent posts Ptarmigan and provoke some intriguing ideas. I agree with you that the majority of the gunboat conversions on the Western waters were done by removing cabins, lowering the machinery, protecting the same and placing guns on open mounts. When I first started this research I had to decide how to organize my files based on vessel type. As this period experienced a rapid transition in technology it is not always easy to strictly define and categorize certain types of vessels. I cannot use the simple definition of, 'I know an ironclad when I see one'. That won't work. In most of the existing CSN documentation the most frequently used term is 'gunboat', for both wooden gunboats and known ironclads. Occasionally one will see 'ironclad gunboat', 'ironclad ram', and (among Charleston and Richmond ironclads) 'ironclad sloop'. I assume the last term carried over from the wooden navy to denote a warship with all of its guns on one deck and had nothing to do with the mercantile 'sloop' which denotes a one mast vessel.

I decided to use the term 'ironclad' to describe: any armed vessel that by construction or design was intended to have the majority of its exposed structure covered by armored protection. This differs from 'gunboat' or 'protected gunboat' which is used to describe: any armed vessel with either a wooden hull or iron hull that is fitted with limited armor to protect vital structures such as machinery or magazines. The last definition includes gunboats with cotton armored bulwarks, iron armored bulwarks and the 'tinclads'. As for examples, I consider the CSS Barataria a 'protected wooden gunboat' or 'tinclad' and not a true 'ironclad'; the same goes for the J. A. Cotten, Stevens, and other New Orleans conversions. By the way, the photograph of the General Bragg after capture clearly shows her cut down railings and the protective bulwarks extending above the main deck but not to the floor of the cabin deck. There is a gap there.

If New Orleans had not fallen, I do think the Mobile would have remained in Berwick Bay as a 'protected gunboat' and served in coastal defense. I don't think her initial conversion was intended to be into an ironclad as defined above. As you've noted above her conversion did involve lowering the boiler further into the hull. I don't know how much further it could have been lowered as the R. & N. workbook suggests it was already in the hold. Perhaps if they had taken it off the boiler blocks and used shorter ones they could have gotten it a little lower. But still a portion of it would have projected above the main deck. As a merchant that portion of the boiler with breechings and funnel was probably housed in an extended deck structure that was aft the main passenger cabin. In multiple sources about the Mobile, it is noted that a 'wooden casemate' was fitted at Yazoo City and was awaiting iron plates or other iron armor for completion. From fortification terminology a 'casemate' is a 'vaulted or roofed chamber with an opening for arms'. This contrasts with a simple open, walled structure as seen with the USN conversions of the Tyler, Lexington and Conestoga. In addition to these distinctions, I have not found any other documentation, vouchers or bills associated with further work on the Mobile from the December 1861 to April 1862 period. The only major structural change made that I can verify, was the removal of the rig prior to her relocation up river.

Let's look at Brown's work on the Arkansas. Why didn't he take iron from the Mobile? Well, the Mobile was being actively used as a guard gunboat at the time. Brown had other sources for iron if he really wanted it. He could have easily salvaged the iron armor from the gunboats Van Dorn and Livingston which were burned just prior to his arrival. So why did he use sheet iron on the Arkansas and not salvaged bar iron? I think he was pressed for time and wanted to get the Arkansas to Vicksburg as soon as possible. I think his experience in doing that colored his decision about the conversion of the Mobile. As is well known, the Arkansas suffered significant damage and casualties in her run. In places, her iron armor was clearly defeated. If he was going to have a good gunboat for use I think he wanted one that could provide better protection for its crew.

Now let's consider the Mobile and her limited displacement and dimensions. If I add 3" for the deck planking (remember the extra sheathing placed in Brashear City), 10" for the keel (all estimated) to the 7'9" depth of hold, I have her deck being 8'1" above the keel. This places her deck at midship some 17" above the WL at standard loaded conditions with a 6'6" draft. With a heavy load she loses 12". If we add a casemate with some form of iron armor I think her deck would drop to about 5" or 6" above the WL at midship. It would follow the original sheer and be higher both fore and aft. Moreover, if she originally had a 30" or 36" railing that was cut down to 12" her bow could have been anywhere from 17" to 30" above the WL depending upon the sheer. I think with a short casemate containing fore and aft pivots on standard circular rails (not heavier turntables) and two short 32pdrs on Marsilly carriages, she could have handled the weight. I would not have taken her to sea, but I would have used her on the rivers and coastal areas.

To answer your other questions I am not aware of any iron plate rolling facilities in Yazoo City. I think any armor would have been railroad iron or plate iron from Selma or Atlanta. Brashear City did have some limited foundry shops as did nearby Franklin. Franklin also had at least two shipyards and an engine builder. That area of Louisiana is known as 'Sugarland' because of the large plantations and associated facilities used for processing cane into sugar. All of the distilleries and presses used steam engines, boilers and their associated equipment. There were local engineers and mechanics in the area who could have easily lent their talents to gunboat construction.

All the best,
Bil
 
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