CSS Mobile Ironclad

Ptarmigan

Private
Joined
Jul 21, 2013
Bill I am extremely grateful for your shared research, without it I would have no idea of what any of these vessels looked like as I have gleaned only basic data from my UK sources and these inspections reports plus other snippets of information you have written down are priceless. I am but a dwarf standing on a giants shoulder because without your data I would know nothing.

Here is an interesting calculation , the Mobile had a nett tonnage of 282 tons. which means she was rated as being able to carry such a weight in cargo. One cubic foot of iron weights 491 lbs , slice that into thirds and you get the weight of 4 inches of iron plate one foot square as 163lb. The smallest dimension of a Arkansas type casemate for 4 guns (assuming the lowering of the boiler made the deck flush) would be 15ft for each pivot gun and 10 feet for each broadside gun plus 10 feet for the stack and engine room ventilation with a minimum deck height of 8 feet to work the guns. We now have a casemate 60 feet long by 8 feet high. Taking the weight of the iron.

we have (60 + 28) x 2 sides x 8 ft = 1408 ft squared ,

weight of iron armour 1408sqft x 163lb = 229504 lbs ,

converted into tons we have 229504/2000 = 115 tons

Calculating the backing of 12 inch pitch pine timber at 52lb per cubic foot (not including the weight of the timber frame) , we have

1408sqft x 52lb = 73216 / 2000 = 36 tons.

Total weight for 4 inches of iron plate with 12 inches of pitch pine backing = 151 tons of extra weight .

The use of green timber would increase this weight still further and you would need to add the weight of the framing material plus grating and also the weight of the 4 guns and carriages plus stores and ammunition but this would probably make the total weight of around 170 tons. now this is not 170 tons stored below the waterline in the hold but a large amount of top weight amounting to 60% of her cargo capacity situated above the waterline which would call into question her stability, this being a calculation of a vessels beam when taking into account her topweight. Of course the size of the casemate is open to argument as is the amount of wooden backing as we just don't know and I am only quoting typical figures but either way it gives some indication of the issues converting a vessel of a modest size into a Arkansas style ironclad.

One other historical fact of note is the lack of any type of armour available let alone rolled 2 inch plate at this time. When Montgomery's RDF vessels came North partially completed from New Orleans, the vessels stopped off at various riverside towns and begged for railroad iron and in many cases it was not forthcoming or had to be obtained from the local authorities by force, such was the shortage that probably only the front glacis of some of the RDF vessels was armoured and some failed to obtain any iron at all. I suspect that the same situation existed on the Yazoo during this time and any iron, let alone iron plate would be virtually unobtainable .
 
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georgew

First Sergeant
Joined
Oct 1, 2010
Location
southern california
Bill I am extremely grateful for your shared research, without it I would have no idea of what any of these vessels looked like as I have gleaned only basic data from my UK sources and these inspections reports plus other snippets of information you have written down are priceless. I am but a dwarf standing on a giants shoulder because without your data I would know nothing.

Here is an interesting calculation , the Mobile had a gross displacement of 450 tons. One cubic foot of iron weights 491 lbs , slice that into thirds and you get the weight of 4 inches of iron plate one foot square as 163lb. The smallest dimension of a Arkansas type casemate for 4 guns (assuming the lowering of the boiler made the deck flush) would be 15ft for each pivot gun and 10 feet for each broadside gun plus 10 feet for the stack and engine room ventilation with a minimum deck height of 8 feet to work the guns. We now have a casemate 60 feet long by 8 feet high. Taking the weight of the iron.

we have (60 + 28) x 2 sides x 8 ft = 1408 ft squared ,

weight of iron armour 1408sqft x 163lb = 229504 lbs ,

converted into tons we have 229504/2000 = 115 tons

Calculating the backing of 12 inch pitch pine timber at 624 lb per cubic foot (not including the weight of the timber frame) , we have

1408sqft x 624 lb = 878592 / 2000 = 439 tons.

Total weight for 4 inches of iron plate with 12 inches of pitch pine backing = 554 tons of extra weight on a vessel of 450 tons gross.

Now my contention is , either she didn't have the normal 4 inch thickness of armour typical of 1863 or she had the more modest 30 ton Louisiana style machinery protection and an open gundeck . Of course the size of the casemate is open to argument as is the amount of wooden backing as we just don't know and I am only quoting typical figures but either way it gives some indication of the issues converting a vessel of a modest beam into a Arkansas style ironclad.
One other historical fact of note is the lack of any type of armor available let alone rolled 2 inch plate at this time. When Montgomery's RDF vessels came North partially completed from New Orleans, the vessels stopped off at various riverside towns and begged for railroad iron and in many cases it was not forthcoming or had to be obtained from the local authorities by force, such was the shortage that probably only the front glacis of some of the RDF vessels was armored and some failed to obtain any iron at all. I suspect that the same situation existed on the Yazoo during this time and any iron, let alone iron plate would be virtually unobtainable .
Just a comment. The shortage for ironing you mention actually affected the first 3 rams sent north. They were unable to get iron for completion at Vicksburg and ended up removing iron from a RR line in Arkansas. 2 of the rams went north with their mandated stern chasers, the Bragg went north without her guns, but apparently had received both fore and after pivot carriages married to ordnance secured upriver. It is very likely that the ironing on the RDS boats varied between 1-inch bar or strip iron. The iron from the RR in Arkansas was from a newer line and probably T-rail laid vertically on the forward panels of the casemate(s). To the best of my knowledge none of the RDS boats had plate iron of any thickness. Are you sure about your weight numbers on the pine timber? And is it based on new milled or dried which could reduce the unit weight up to 50%? I also question that the backing for the iron was 12 inches thick. I think you will find it was framed with thick beams, but then planked with 4 inch timber, then pressed cotton and planked again under the iron on the sides of the casemate which was about 1 inch iron. Oh, minor point. The casemates were only ironed forward of the wheels and at least originally had no ironing on the top of the casemate. Bragg had a totally different style of protection. Lt. Kennon's description of this type is found in a Century Magazine issue after the war and applies to Bragg and Resolute of the RDS and both Louisiana State gunboats at the forts.
 

Ptarmigan

Private
Joined
Jul 21, 2013
The 12 inch timber backing was a hypothetical figure for an ironclad vessel . I was not describing a cotton clad but a conversion of Mobile into a casmate ironclad , a smaller version of Arkansas that was described by others at the start of the thread , The timber weight used was for dried timber whereas green timber was probably used , the weight changed during the initial writing of my contribution due to an error I made in the calculation regarding the length of the timber but I spotted my error and as far as I know the calculation, all be it hypothetical is now correct. I cited the RDF problems in obtaining armour just as an example of the shortage of resources for building ironclads in this region , a problem that plagued the construction of the Arkansas and Tennesee. I hope this clears up a few issues . I am in no way certain that Mobile was not completed as a small Arkansas as some here suggest , it's just that I feel a Louisiana type gunboat was more likely but have no concrete evidence either way.
In my mind the protection of Mobile's machinery would have originally followed the pattern described by Lt Kennon as she too was a vessel constructed to a similar pattern all be it powered by a screw not paddles .
 
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Bil R

Private
Joined
Mar 23, 2011
Location
Massachusetts
Hello Ptarmigan,

Thank you for the kind words. You raise some valid concerns regarding the weights of a fitted casemate with iron armor. Four inch plate armor was not available to the CSN as far as I know. Scofield & Markham, Tredegar and Selma could produce 2" rolled plate and multiple layers could be used to achieve the desired thickness. Six inches was wanted by different commanders for the forward shields and pilot houses of various ironclads in Mobile, Charleston and Richmond later in the war. As you mention, iron armor of any type would be difficult to come by in 1863 at Yazoo City.

The challenge with the Mobile is we do not know at this time the planned composition of her casemate. It seems as if each known Confederate ironclad had a unique mixture of wooden layers backing the armor. They could be of different woods of variable thickness and oriented in different, contrasting directions. I think it is highly likely than she would have been fitted with railroad iron, and depending upon the source, those rails could have been of different weights (Look at the thread 'CSS Louisiana - new plans; entry 23 for rail weight calculations and casemate estimates). In order to save some weight, it may have been planned to use sheet iron only on the roof. Or only have bar iron in the form of a grate covering an otherwise open roof.

These are all questions we don't have answers to. As George pointed out and you mentioned as well, I think the Mobile's machinery space was protected as the other ocean-going steamers converted in New Orleans. This involved wooden bulwarks backed by compressed cotton and fronted with iron rails surrounding the machinery spaces. These bulwarks rested on the hold bottom and extended above the main decks. They were quite effective. The only crew not injured on the Governor Moore were those serving the engine room. The angled shields or 'cow-catcher' shields were used on shallow hold, western river style gunboats having most of the machinery located on the main deck. While some had boilers lowered in the hold, engines typically remained on the main deck.

Despite the size and weight concerns I am still convinced the Mobile had some type of casemate fitted during her conversion at Yazoo City. One thing I've learned over the years in ACW research is to not underestimate the engineering ingenuity and capabilities of the men involved. While they did not have access to the education, training, instruments, calculators and computers of today, they still possessed fine, sharp minds fully capable of solving whatever problems they encountered.

All the best,
Bil
 

Ptarmigan

Private
Joined
Jul 21, 2013
GEORGEW “I also question that the backing for the iron was 12 inches thick.”

Yes you could well question this as it was a figure conjured up from air by me but take into consideration that I was not describing a cottonclad’s construction but an ironclad like Arkansas as this was what was proposed in the initial part of this thread for the Mobile. the Virginia’s backing was twice this at 24 inches as was the Georgia’s backing. While we are giving out credit where it is due, I also rate your contributions to this forum very highly as well GEORGEW, so thank you.


Bil R. “I think it is highly likely than she would have been fitted with railroad iron”

I agree with you Bil, I don’t think that plate armour was available as nobody has come up with invoices from rolling mills stating they supplied Yazoo City with such stock. I think that if any iron was available then it would be railroad iron but looking at the shortages of this to the RDF I would even question this was available in the quantities required and the weight of a 60 foot casemate clad in RR iron would be even higher. I have calculated that it would have weighed as much as 416 tons based on the weight of Georgia’s green wood casemate and 70lb rail and that's not factoring the weight of the ordnance or framing material . Such a topweight would submerge the vessels 282 ton rated load line by a considerable margin .



Bil R “Despite the size and weight concerns I am still convinced the Mobile had some type of casemate fitted during her conversion at Yazoo City”

I think it was possible but not in the form of what we are familiar with. I am likely to think that a Mississippi gunboat converted from a paddle riverboat will have a cowcatcher bow and cottonclad armour and a coastal steamer would have internal armour as described by Lt Kennon. A light draught coastal steamer would conform to a pattern like Selma with cabins stripped back and no armour and her guns on open decks and an Ironclad built from the keel up would look like Arkansas with a 4 inch armoured casemate enclosing its guns . There are however a few rare anomalies to this, the Barataria did not conform to any of these norms, neither did the Manassas or Diana so we need to keep an open mind while at the same time paying attention to the norms of construction and the availability of materials and facilities.
 
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rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
CSS Selma had 2"iron over "thick timbers" topped with a 3/8" iron deck as an internal citadel around the engines and magazines.

I think Bil is correct to say that CSS Mobile as a protected gunboat would have had a similar means of protection, and that would have remained when she was selected for conversion to an ironclad.
I also think we can all accept that Isaac Newton Brown (One of those men who possessed the attributes described by Bil in spades), would have used his knowledge and experience to create a "mini" Arkansas, but let's not get hung up on the term "ironclad" and it's connotations. CSS Mobile in my estimation was far more likely to have matched the designation "tinclad".
 

Ptarmigan

Private
Joined
Jul 21, 2013
I agree with you Rebel on both points , I think we are probably looking at a tinclad here. One other vessel that didn't match the norms of construction described was the Baltic at Mobile Bay.
 

Bil R

Private
Joined
Mar 23, 2011
Location
Massachusetts
Hello Gentlemen,

This is a good discussion here. Just to clarify a couple of points, in addition to the Baltic being partially armored have you ever noticed how the Cairos are classified as ironclads, and yet the actual armor only covered a small portion of their exposed structures? The 'cow-catcher' shield seen on the RDS gunboats, and probably on the New Orleans converted gunboats was placed on the deck just ahead of the boilers, not on the hull at the bow. It is known that similar style shields were placed on the Drewry and Patrick Henry on the James river. They were intended to deflect and block shots coming bow on to the machinery. Such shields are easily seen in the Simplot painting of the Battle of Memphis. Iron plating, typically in the form of rails was attached to the hull at the bows and wrapped around the stem to conform to the hull shape. A full covering of such protection could offer some protection to boilers lowered into the hull.

Thinking of the Mobile a different arrangement occurred to me. We know that she served in the open waters off Brashear City armed with four guns, three masts, the protected machinery and full stores, probably at her typical load line draft. Her masts and rig were gone prior to arriving in Yazoo City. During her conversion there, Brown spent probably 4 to 6 months doing the work. This was plenty of time to do it to the best of his abilities using local resources. Consider if he had removed all the protective bulwarks and iron that had surrounded the machinery. The removal of that weight, along with the masts and rigging should have given him a sufficient weight reserve to mount a true casemate. The weight of the bulwarks alone may have equaled a third or half of the actual casemate. By placing a casemate he would have increased her draft to a deep load, but she still would have been manageable. By removing the machinery bulwarks he would have depended upon the casemate to protect his crew, guns and machinery, all in one. Do you think that is a workable solution?

All the best,
Bil
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
I agree with you Rebel on both points , I think we are probably looking at a tinclad here. One other vessel that didn't match the norms of construction described was the Baltic at Mobile Bay.
She was converted from a garbage scow or a cotton lighter, sources differ. Her 4" iron which probably didn't extend aft of the wheels was transferred to CSS Nashville.

CSS BALTIC.jpg
 

Ptarmigan

Private
Joined
Jul 21, 2013
Based on the consensus of opinion I submit hypothetical plans for an ironclad with a 60 feet x 20 feet casemate box with vertical sides and sloped ends constructed of vertically mounted 60lb railroad “T” iron laid onto a backing of 18 inch green pinewood supported by a pine framework. The boiler room sides situated amidships are to be protected internally above and below the waterline for a length of 20 feet by the same thickness of armour. No armour is placed on the waterline in other locations but steps may be taken to minimise damage to the steering gear by localised armoured protection.The total weight of the railroad iron and green timber is calculated to be in excess of 129 tons, to which needs to be added the weight of ordnance and the weight of the casemate timber frame. The vessel will be conned from a raised platform situated just forward of the funnel with a small raised armoured pilothouse providing protection for for the pilot and commander and the bow will be reinforced by the bolting a length of railroad iron onto internal reinforcement timbers within the hull itself.

The fore and aft Pivot guns, a 32lb rifle and an 8 inch shell gun will each need to be worked within a 15ft x 18ft deck space with 8 feet of head room and the two deck howitzers mounted in broadside forward of the funnel will of necessity have to be worked on a raised portion of the deck situated above the boilers due to the limited length of the vessels casemate and the fact that the boilers will protrude above the normal deckline. The bulwarks of the entire vessel will be removed in order to provide an improved field of fire although the sheer of the forward deck may limit the vessels pivot gun from firing directly forward.

It can be seen that it may be possible to use heavier “T” rail or thicker backing timber on this build to take the weight up to the maximum of 282 tons but my calculation was made using rail iron with a 6 inch base allowing for three length’s of rail per foot whereas the rail shown on the Georgia has six length’s per foot which seems to imply the base of each rail was only 2 inches wide which looks odd to me as I would expect a minimum width of three inches.

I am unable to show you my drawing as I don't know how to upload anything but text onto this site but she would look very similar to John's original drawing with perhaps a shorter and lower casmate and her funnel further aft.
 
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georgew

First Sergeant
Joined
Oct 1, 2010
Location
southern california
The 12 inch timber backing was a hypothetical figure for an ironclad vessel . I was not describing a cotton clad but a conversion of Mobile into a casmate ironclad , a smaller version of Arkansas that was described by others at the start of the thread , The timber weight used was for dried timber whereas green timber was probably used , the weight changed during the initial writing of my contribution due to an error I made in the calculation regarding the length of the timber but I spotted my error and as far as I know the calculation, all be it hypothetical is now correct. I cited the RDF problems in obtaining armour just as an example of the shortage of resources for building ironclads in this region , a problem that plagued the construction of the Arkansas and Tennesee. I hope this clears up a few issues . I am in no way certain that Mobile was not completed as a small Arkansas as some here suggest , it's just that I feel a Louisiana type gunboat was more likely but have no concrete evidence either way.
In my mind the protection of Mobile's machinery would have originally followed the pattern described by Lt Kennon as she too was a vessel constructed to a similar pattern all be it powered by a screw not paddles .
Most people don't realize that rail for Arkansas' sister-ship was actually stacked at the railhead across the river from Memphis at the time of the battle off Memphis fought by the RDS. You bring up a good point - the issue of protection along the waterline. The large RDS boats and the Louisiana State Gunboats effectively had portions of a double hull added in their hold areas - something the size and beam dimensions of Mobile make unlikely. If Mobile had a casemate I suspect it would have been very short and if similar to Arkansas with vertical sides and sloped fore- and aft- bulkheads. The reason I think it was Brown's plan to have a casemate was the fact that he was still waiting for iron. It is possible that they anticipated applying iron from below the waterline to the main deck, something the Confederates usually did before launching a hull. Your mention of the Cotton and its conversion raises other issues. Cotton had two major advantages as a conversion - she was large and had low-pressure engines. She had the displacement to carry some ironing forward of the wheels and still carry a few heavy guns. You would think think she was vulnerable along the waterline, but this doesn't appear to have been a problem in action. They did not drop her boilers but did put up ironed bulkheads around them. Her guns forward were badly protected from the gun crew's point of view, but did have the advantage of an original deck above them to give some protection from airbursts. The northern squadron of the RDS did adopt something to protect gun crews for those boats with a bow chaser and the Missouri infantry detachments assigned aboard for small arms support. They put up cotton bale barriers and at least one of the drawings of the action off Plumb Point show one of the RDS boats - Van Dorn? so equipped. I don't know if this was done on the Cotton. It seems and obvious idea, provided that the bales were soaked with water before the engagement. We don't seem to have a lot of data on plans for converting some of the larger river steamers up the Yazoo, but I think you are right that the "Louisiana" type conversions would have been used. At least one of the Yazoo boats was large and fast and reported to be converted into a ram, probably the way the Bragg was with extra planking forward and an iron strip facing on the vertical bow.
 

georgew

First Sergeant
Joined
Oct 1, 2010
Location
southern california
I'm a modeler and naval wargaming. In the case of CSS Mobile, I'm contemplating a "what if" wargame of Confederate's holdoff Union forces, are actually able to complete 2 or 3 ironclad conversions at Yazoo City, and then breakout from the Yazoo River into the Mississippi River in 1863 with the "Yazoo Monster" and Mobile (conversion to ironclads done), and possibly another converted or partially converted ironclad from Ivy, General Polk, and General Van Dorn, and several of the cottonclads that were also up the Yazoo. I like to get the models as correct as possible, so am interested in any details available on the Mobile. Generally, if known, dimensions and tonnage in their original form...
It occurs to me that maybe we should seek a consensus of just what role Brown intended the Mobile to serve? It is also important to revisit the issue of how and where she was being converted. Do we know for sure whether Mobile was still up on ways when torched, or had she already been launched? If she was in the water then ironing of the hull had already been done or totally skipped. Her rails could have been cut down while moored to a wharf, workboat or barge. They had a sawmill at the Yazoo yard so wooden under structures shouldn't have been a problem. The nearest rail line to bring in iron was 25 miles away. Brown was forced to dragoon every blacksmith for miles around to fit iron on Arkansas and those left after the ironclad sortied might have been put to use making iron fasteners which had been hard to come by for months. Now we get to the issue of why a small boat like Mobile was being converted into something else. In design school one of the first traditional lessons is the three 'F's'. Form follows function. What role was Mobile intended to play? Most of us make an assumption that they would place large guns on her. So who was going to man those guns as Brown had stripped out most of the naval personnel for Arkansas? Many of the survivors of that crew had been transferred to other duties elsewhere. Based upon other developments on the west side of the Mississippi you would expect gunners to come from artillery units. There was still a battery on a ridge overlooking Liverpool Landing and the steamer Capitol was still in place plugging an opening made to let the Arkansas out. So would the presence of a small gunboat or tinclad be that great of a reinforcement for the existing battery? If Mobile was intended as a water battery to cover the obstruction and prevent Union boat parties from placing explosives to degrade the obstructions, particularly the relatively fragile hulk of the Capitol then the question is why would Mobile need to be ironed? Wooden emplacements faced with sandbags would have been sufficient for available Army field caliber guns. Flat trajectory protection from Union gunboats would have been provided in part by the obstructions and barges or hulks could have been moored alongside for a similar purpose. Billeting space could have been provided by a wharf boat or smaller steamer on the opposite side of Mobile. There is the possibility that early on Brown had illusions of breaking out with the Yazoo monster and wanted the Mobile as a tender.
 
Joined
Sep 28, 2013
Location
Southwest Mississippi
If only new research about the Yazoo City Navy Yard should surface . . . I think many pieces of many puzzles might help us understand what was really going up the Yazoo River.

We all know that the history of the CSS Arkansas is well documented.

But facts about the legendary "Yazoo Monster" remain an enigma.
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
If only new research about the Yazoo City Navy Yard should surface . . . I think many pieces of many puzzles might help us understand what was really going up the Yazoo River.

We all know that the history of the CSS Arkansas is well documented.

But facts about the legendary "Yazoo Monster" remain an enigma.
What do we know? "She measured 310ft x 70ft" - 4.43 to 1, near enough to a Nashville type overall proportions to strongly indicate she was one Powered by 2 x 40ft sidewheels, driven by four engines, and with 2 x 8ft screws (CSS Tennessee's machinery?) . Armour was to be 4.5", plate by Shelby Iron Company, over 24" timber. Casemate sloped at 35 degrees.
Design was John L. Porter and builders T. Weldon & J Mc Farland at Yazoo City Navy Yard.
Described as "skiff built, both ends the same - another characteristic of a "standard" Porter hull below the built on knuckle.
On those basics I have drawn up and used in my book, the projected appearance plan below.
However I feel I, N. Brown, under pressure to get her completed utilising whatever he had to hand and lacking supervision (No constructor was appointed for the facility may well have produced a very different vessel, albeit retaining the methods of propulsion. I have not, as yet, put my thoughts on this to paper.

J.L.Porter's Yazoo Monster. css new orleans.jpg
 

rebelatsea

1st Lieutenant
Joined
Mar 30, 2013
Location
Kent ,England.
It occurs to me that maybe we should seek a consensus of just what role Brown intended the Mobile to serve? It is also important to revisit the issue of how and where she was being converted. Do we know for sure whether Mobile was still up on ways when torched, or had she already been launched? If she was in the water then ironing of the hull had already been done or totally skipped. Her rails could have been cut down while moored to a wharf, workboat or barge. They had a sawmill at the Yazoo yard so wooden under structures shouldn't have been a problem. The nearest rail line to bring in iron was 25 miles away. Brown was forced to dragoon every blacksmith for miles around to fit iron on Arkansas and those left after the ironclad sortied might have been put to use making iron fasteners which had been hard to come by for months. Now we get to the issue of why a small boat like Mobile was being converted into something else. In design school one of the first traditional lessons is the three 'F's'. Form follows function. What role was Mobile intended to play? Most of us make an assumption that they would place large guns on her. So who was going to man those guns as Brown had stripped out most of the naval personnel for Arkansas? Many of the survivors of that crew had been transferred to other duties elsewhere. Based upon other developments on the west side of the Mississippi you would expect gunners to come from artillery units. There was still a battery on a ridge overlooking Liverpool Landing and the steamer Capitol was still in place plugging an opening made to let the Arkansas out. So would the presence of a small gunboat or tinclad be that great of a reinforcement for the existing battery? If Mobile was intended as a water battery to cover the obstruction and prevent Union boat parties from placing explosives to degrade the obstructions, particularly the relatively fragile hulk of the Capitol then the question is why would Mobile need to be ironed? Wooden emplacements faced with sandbags would have been sufficient for available Army field caliber guns. Flat trajectory protection from Union gunboats would have been provided in part by the obstructions and barges or hulks could have been moored alongside for a similar purpose. Billeting space could have been provided by a wharf boat or smaller steamer on the opposite side of Mobile. There is the possibility that early on Brown had illusions of breaking out with the Yazoo monster and wanted the Mobile as a tender.
All we know is that she was ordered to Yazoo City (by whom, Porter ?) to be converted to a 2 gun casemate ironclad. That has caused more than one author to report Mobile as an Albemarle type. While John L. may have sent the plans, and we don't know that, I think we all disagree in light of what is known about the vessel.
 
Joined
Sep 28, 2013
Location
Southwest Mississippi
What do we know? "She measured 310ft x 70ft" - 4.43 to 1, near enough to a Nashville type overall proportions to strongly indicate she was one Powered by 2 x 40ft sidewheels, driven by four engines, and with 2 x 8ft screws (CSS Tennessee's machinery?) . Armour was to be 4.5", plate by Shelby Iron Company, over 24" timber. Casemate sloped at 35 degrees.
Design was John L. Porter and builders T. Weldon & J Mc Farland at Yazoo City Navy Yard.
Described as "skiff built, both ends the same - another characteristic of a "standard" Porter hull below the built on knuckle.
On those basics I have drawn up and used in my book, the projected appearance plan below.
However I feel I, N. Brown, under pressure to get her completed utilising whatever he had to hand and lacking supervision (No constructor was appointed for the facility may well have produced a very different vessel, albeit retaining the methods of propulsion. I have not, as yet, put my thoughts on this to paper.

View attachment 392866
Thank you.

I really need to order your book !

A few years ago, I came across the reported location of the HQ office of the CSA Navy in Mississippi.

The office seems to have been across the street from our original capitol.
(about 40 miles Southwest of Yazoo City).

Anyway, Jackson was burned three times by the Union within two years, so I'm sure those official records of the Western CSN operations are forever lost.

I do have hope there may be some records of the Western CSN that still may exist "undiscovered" .
 

Biscoitos

Corporal
Joined
May 14, 2020
Thank you.

I really need to order your book !

A few years ago, I came across the reported location of the HQ office of the CSA Navy in Mississippi.

The office seems to have been across the street from our original capitol.
(about 40 miles Southwest of Yazoo City).

Anyway, Jackson was burned three times by the Union within two years, so I'm sure those official records of the Western CSN operations are forever lost.

I do have hope there may be some records of the Western CSN that still may exist "undiscovered" .
Jackson is about 50 miles south and slightly EAST of Yazoo City. A point due south of Yazoo City would be between Bolton and Clinton.
 

georgew

First Sergeant
Joined
Oct 1, 2010
Location
southern california
GEORGEW “I also question that the backing for the iron was 12 inches thick.”

Yes you could well question this as it was a figure conjured up from air by me but take into consideration that I was not describing a cottonclad’s construction but an ironclad like Arkansas as this was what was proposed in the initial part of this thread for the Mobile. the Virginia’s backing was twice this at 24 inches as was the Georgia’s backing. While we are giving out credit where it is due, I also rate your contributions to this forum very highly as well GEORGEW, so thank you.


Bil R. “I think it is highly likely than she would have been fitted with railroad iron”

I agree with you Bil, I don’t think that plate armour was available as nobody has come up with invoices from rolling mills stating they supplied Yazoo City with such stock. I think that if any iron was available then it would be railroad iron but looking at the shortages of this to the RDF I would even question this was available in the quantities required and the weight of a 60 foot casemate clad in RR iron would be even higher. I have calculated that it would have weighed as much as 416 tons based on the weight of Georgia’s green wood casemate and 70lb rail and that's not factoring the weight of the ordnance or framing material . Such a topweight would submerge the vessels 282 ton rated load line by a considerable margin .



Bil R “Despite the size and weight concerns I am still convinced the Mobile had some type of casemate fitted during her conversion at Yazoo City”

I think it was possible but not in the form of what we are familiar with. I am likely to think that a Mississippi gunboat converted from a paddle riverboat will have a cowcatcher bow and cottonclad armour and a coastal steamer would have internal armour as described by Lt Kennon. A light draught coastal steamer would conform to a pattern like Selma with cabins stripped back and no armour and her guns on open decks and an Ironclad built from the keel up would look like Arkansas with a 4 inch armoured casemate enclosing its guns . There are however a few rare anomalies to this, the Barataria did not conform to any of these norms, neither did the Manassas or Diana so we need to keep an open mind while at the same time paying attention to the norms of construction and the availability of materials and facilities.
Barrataria was an oddball, largely because she was in part plated with pre-drilled plate captured dockside at New Orleans and intended for the Mississippi. Gen Butler wrote a letter to Washington concerning this. The weight of T-rail could vary a bit depending on its age, usually in the mid-60's lbs. Some of the southern rail was actually rolled in Wales and considered better wearing than US sources. Then there is the issue of strip iron from old roads stores for repair. Manassas was ironed with strip iron about 2 1/2 inches wide from a New Orleans line. Strip rail could be had in weights down to 16 lbs/yd, used for trolley or mine track.
 

georgew

First Sergeant
Joined
Oct 1, 2010
Location
southern california
All we know is that she was ordered to Yazoo City (by whom, Porter ?) to be converted to a 2 gun casemate ironclad. That has caused more than one author to report Mobile as an Albemarle type. While John L. may have sent the plans, and we don't know that, I think we all disagree in light of what is known about the vessel.
As a civilian employee of the CSN I don't think Porter had the authority to order Mobile up-river. The senior officer at New Orleans certainly had the authority - Whittle?
 
Joined
Sep 28, 2013
Location
Southwest Mississippi
Jackson is about 50 miles south and slightly EAST of Yazoo City. A point due south of Yazoo City would be between Bolton and Clinton.

I was born and raised in Jackson.

I do know the distance between these locations.
A 10 mile difference was not much of an issue during the 1860s.
The maps of that era were accurate, but far from exact.
But it doesn't matter, Yazoo City, Clinton and Bolton haven't moved.

However, I do thank you for providing the exact geographic coordinates of those sites

You just plotted the Central Business District of Raymond.
 
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