Hello John,
Fine work as always, it is another excellent contribution. As you know the Louisiana has intrigued me as well and I appreciate the thoughts and revisions you have made to the evolving understanding of this vessel. It is frustrating that there is so much documentation, and yet so many contridictions too. With those limitations in mind I wish to offer a few thoughts.
First, I would not get too concerned about the displacement disparities. Weight calculations and displacement determinations were an inaccurate science in that period and some of the brightest designers had issues with that (Ericsson - Passaic class, Porter - Virginia conversion, Stimers - Casco class, etc.). Murray was a talented designer and builder having produced over 120 steamboats on the Western rivers. As noted, when launched it was quickly apparent that his calculations were in error and the Louisiana drew too much. Why did this happen? I think that Murray was accustomed to building shallow draft, lightly built vessels. The Louisiana, although of shallow draft (intended), was a warship. By contract all of her fittings and scantlings were larger, more closely spaced, and heavily fastened. She was a different breed of ship than Murray had built before. Despite this error, Murray was experienced enough to modify the design while fitting out to compensate for this miscalculation. I do believe he built the hull to contract specifications (264'pp x 62' x 7'). A hull to those specifications would have an external deck edge height of about 9'. To make a draft of 11' would require a much deeper hull (deck edge height at least 13') which would have entailed a significant contract modification with added time and expense. It probably would have resulted in the fitting of berth deck in the hold. While possible, I have not seen any evidence that the Louisiana was altered in that manner. So what did he do?
As you've noted he reduced the casemate length which had the secondary effect of reducing her armament. I believe the reduction was done from the bow rather than the stern as any further reduction in the aft portion of the casemate would have compromised the space needed for the guns and the aft wall of the wheel well. By altering the stores kept in the forward area he could maintain her trim. Murray claims to have mounted all the armor as called for in the contract. I believe he reduced both the waterline belt by 3' (intended 5', actual est. 2') and the horizontal deck armor. Initially the deck armor was to be 2" but it was reported as only 1/4". In a previous post I had calculated that he probably mounted about 464.8 tons out of about 500 tons purchased. So he could reasonably make that claim. The reduction in armament, while not desired, would not have a major impact on her fighting ability but the weight reduction would be significant. I think all three factors (casemate reduction, armor reduction, gun reduction) were the primary means of minimizing her final displacement.
He also modified the machinery. I think in his original concept Murray envisioned building an ironclad with tandem centerwheels of typical large steamboat dimensions. Imagine the Louisiana fitted with 36' to 40' wheels. When the design was reviewed and the contract drawn up such ambitions were curbed. It was intened to fit two wheels of 27' diameter by about 18' width. We know that there were concerns about this arrangement and interference of the aft wheel by the fore wheel. Morgan reports that the fore wheel was smaller than the aft one to compensate for this. After much thought I believe it was reduced in width rather than diameter (27' x ~10'-12', rather than 18'). Why? A reduction in diameter but not width would still result in turbulent flow across the entire wheel well. A narrower wheel of the same diameter would still give you similar power but at least the edge water would not be as turbulent. Moreover, in every sketch of the Louisiana, the wheel wells appear to be of similar size. Both Mitchell and Morgan report the wheels in tandem. I think the Waud sketch suggesting staggered wheels was done in a hurry during the battle and does not reflect the actual arrangement.
Her secondary machinery presents another dilemma. We know that McLean & Co. removed, transported and remounted the HP engines and boilers from the Ingomar. This was more complicated and took longer than expected. We also know that Robert Kirk forged new screw shafts for her suxiliary propellers. Morgan states that the machinery (paddle and screw) was tried while in New Orleans and found to be ineffective. Morgan also reports that she received the screw machinery from two small tugs that had been seized. Revieiwing both the antebellum and postbellum New Orleans ship registers I can account for the fates of all screw tugs except for two, the Decatur and Union. Both were owned by Northern parties and both had identical machinery built by the same firm (18' x 18" Reaney, Neafie & Co.). They would have been ideal for seizure and use of the Louisiana. These engines were probably in the 80 to 100hp range. I have not come across any indication that Kirk received a new machinery contract for a pair of larger, 500hp engines. That would have been a major contract of some expense. Kirk did forge new shafts as apparently the aft lines in Louisiana did not give sufficient space to mount the engines as they had been in the tugs. Now of course, differing from Morgan, Youngblood reports that the machinery was not fully complete or trial ready until the morning of April 24th. That probably represents the true completion date. I believe that they were modifing the machinery up until that time to get as much power as possible out of the arrangements. It is known that larger screws were fitted in an attempt to improve their efficiency.
Speaking of other details I have not come across any indication that the Louisiana was intended to be fitted with a ram or act as a ram. It is certainly possible though. There is a sketch by Nestell I believe, that shows a structure on her aft casemate that may represent the aft conning tower. That is the only indication I have seen that it may have been fitted. Regarding her gunports were they truly oval or square as seen in sketches? I think they were both. I think they were built as square. When at the forts MacIntosh ordered them to be modified to an oval form which took an additional five days of work. In all likelihood the team of carpenters were able to design, measure, cut and fit wooden inserts to the gunports to make them oval. In other CSN ironclads (Mississippi, Virginia) a cast iron frame was fitted outboard to receive the port hinges and form the port edges. The facilities and time to do that type of work were not available at the forts, hence only the original square gunports are seen externally. Closer inspection would probably reveal the hastily fitted wooden inserts. While limiting arcs of fire they would at least give some additional protection to the crew. The waterway fitted around the upper deck was triangular in cross section rather than plan form. That would allow easier sweeping of water from the deck rather than having multiple drainage holes. One last comment. I like the all white casemate scheme. Where is the MacIntosh reference for this? Was he referring to the external casemate or internal casemate? Externally, it would certainly help in lowering the temperature aboard. Internally it would help lighten up a dark area. The reason I ask this is that all the paint vouchers thus seen for New Orleans CSN vessels usually name black or lead gray for external paint. State and River Defense vessels are painted black, lead gray, brown and ochre.
Thanks again for all your contributions. I always look forward to reading your posts.
All the best,
Bil
Bringing the