The plan and construction of the “Merrimac.”
John M. Brooke, Commander, C. S. N.Early in June, 1861, the Secretary of the Navy of the Confederate States asked me to design an iron-clad. The first idea presenting itself was a shield of timber, two feet thick, plated with three or more inches of iron, inclined to the horizontal plane at the least angle that would permit working the guns; this shield, its eaves submerged to the depth of two feet, to be supported by a hull of  equal length. There was nothing novel in the use of inclined iron-plating. It was apparent that to support such a shield the ends of the vessel would be so full as to prevent the attainment of speed; and that in moving end on even a small sea would prevent working the bow or stern gun. It then occurred to me that fineness of line, protection of hull, and buoyancy with light draught, could be obtained by extending the ends of the vessel under water beyond the shield, provided the shield were of sufficient length to give the requisite stability. Considering, then, the liability to the banking up of water over these submerged ends, I erected upon each a decked superstructure of ship-iron, carried up from the sides of the submerged parts to a height above water not greater than would permit free use of the guns, and of the usual form of hull above water. Water could be admitted or taken from them. I submitted to the secretary outline drawings,sheer, body and deck plans, with explanations,and he approved and adopted this novel form. In reply to my suggestion that Naval-Constructor John L. Porter and Chief-Engineer William P. Williamson should be called to Richmond, that we might put the plan in execution, he replied that a practical mechanic would be sent from the Norfolk yard. This mechanic — a master ship-carpenter-came; but as he was lacking in confidence and energy, and was averse to performing unusual duty, he was permitted to return to the yard. Messrs. Porter and Williamson were ordered to Richmond for consultation on the same general subject, and to aid in the work. They met the secretary and myself on the 23d of June, 1861. Mr. Porter brought and submitted to the secretary a model described by the latter in a report dated March 29th, 1862, to the congress of the Confederate States, as “a fiat-bottomed light-draught propeller, casemated battery, with inclined iron sides and ends.” The hull of this model did not extend beyond the shield. The secretary then called the attention of Messrs. Williamson and Porter to the plan proposed by me, which had been adopted by the department. The drawings were laid before them, the reasons for extending the hull under water beyond the shield were given, and both approved it. As the drawings were in pencil, the secretary directed me to make a clean drawing in ink of the plan, to be filed in the department. Messrs. Porter and Williamson were directed to ascertain if suitable engines and boilers could be obtained. Mr. Porter offered to make the clean drawing, as “being more familiar with that sort of work.” Accepting the offer I went with Williamson to the Tredegar works, where we learned that there were no suitable engines in the South. Williamson then said he thought the engines of the Merrimac could be used, but that the vessel would necessarily draw as much water as the Merrimac, and it would not be worth while to build a new hull, as enough of the old hull remained to carry out the plan. Mr. Porter and I thought the draught too great, but that we could not do better. We so reported to the secretary, who concurred. That there might be official record of results of consultation, as there was of the original plan, he directed us to consider and report upon the best mode of making the Merrimac useful, which we did in accordance with the views above stated. Mr. Williamson and Mr. Porter returned to Norfolk, the former to adapt and repair the engines, the latter to cut the ship down, submerge her ends, etc. To me was assigned the preparation of armor, construction of guns, etc. On the 11th of July Mr. Porter submitted to the secretary drawings, based upon actual measurements of the ship and on the plan of submerged extended ends, which I had presented, and which had been unanimously approved. Having reference to this working plan and its details, the secretary issued the following order:
This and a similar order were construed by Mr. Porter to credit him with the origin of the plan, and served as a basis to a published claim after the action in Hampton Roads, which led to a call by the Confederate House of Representatives, upon the Secretary of the Navy, for information as to the origin of the plan, and to the settlement of the question by a patent, No. 100, granted me by the Confederate States, 29th July, 1862. This patent is still in my possession.
John L. Porter, Naval Constructor, Confederate States.In June, 1861, I was ordered to Richmond by Secretary Mallory, and carried up with me a model of an iron-clad for harbor defense. Soon after my arrival I was informed by the secretary that I had been sent for to confer with Chief Engineer W. P. Williamson and Lieutenant J. M. Brooke in arranging an iron-clad. We went into Engineer Williamson's office, and held a consultation, the result of which was this report to the secretary:
I returned immediately to the Gosport Navy Yard, and made a working drawing of the whole thing, put my shield on it, which I had in my model, and returned to the secretary, July 11th, 1861, who had the following order made out, and placed in my hands by himself:
I came immediately back to the Navy Yard and commenced this great work, unassisted by mortal man so far as the plans and responsibilities of the hull and its workings were concerned as an ironclad. The second letter which came from the department about this great piece of work is as follows:
In April, 1846, I had been stationed in Pittsburg superintending an iron steamer, when I conceived the idea of an iron-clad, and made a model with the exact shield which I placed on the Merrimac. Lieutenant Brooke tried for over a week to carry out the wish of the department, but failed entirely to produce anything, whereupon I was called on by the secretary. After I had made the plan of the Merrimac, and had submitted it to the department, not to Lieutenant Brooke, and when everything was fresh in the mind of the secretary, he had the order of July 11th made out and placed in my hands, to Flag-Officer Forrest, to proceed with the work with all dispatch. No man save myself had anything to do with the converting of that ship into an ironclad,--I calculated her displacement, weight, etc., and cut her down to suit, and no man save myself knew what she would bear. Lieutenant Brooke came to the yard once while the ship was being prepared, and stated that he had tried experiments on three inches of iron and it would not stand the fire. I then told him to put on another inch, making four inches; he asked me if she would bear it. I told him she would, and the armor was changed to four-inches. All the inboard plans and arrangements were made by myself, and the whole working of the ship; Lieutenant Brooke superintended the armor and guns; Engineer Williamson superintended the machinery, and John L. Porter the construction of the hull. The accompanying drawing is a correct representation of a cross-section amidships. She had only decks, gun and berth. Her shield sloped at an angle of 35 degrees; her rudder and propeller were well protected by a heavy fan-tail; her prow was of cast-iron securely fastened to the ship, and so well secured that though it was broken in two by striking the Cumberland a glancing blow, the fastenings to the vessel were not broken loose. Her deck ends were two feet below water and not awash, and the ship was as strong and well protected at her center-line as anywhere else, as her knuckle was two feet below her water-line, and her plating ran down to the knuckle and
|Cross-section of “Merrimac,” from a drawing by John L. Porter, Constructor. a-4 inches of iron. B--22 inches of wood.|