The Civil War Connections Blog

…zealously claiming the attention…

The Ironclad Board is not impressed...

Report on Ironclad Vessels

Navy Department
Bureau of Yards and Docks,September 16, 1862


The undersigned, constituting a board appointed by your order of the 8th ultimo, proceeded to the duty assigned to them, in accordance with the first section of an act of Congress, approved 3d of August 1861, directing the Secretary of the Navy “to appoint a board of three skillful naval officers to investigate the plans and specifications that may be submitted for the construction or completing of iron-clad steamships or steam batteries to be built; and there is hereby appropriated, out of any money in the treasury not otherwise appropriated, the sum of one million five hundred thousand dollars.”

Distrustful of our ability to discharge this duty, which the law requires should be performed by three skillful naval officers, we approach the subject with diffidence, having no experience and but scanty knowledge in this branch of naval architecture.

Application was made to the department for a naval constructor, to be placed under our orders, with whom we might consult; but it appears that they are all so employed on important service that none could be assigned to this duty.

The construction of iron-clad steamships of war is now zealously claiming the attention of foreign naval powers.France led off; Englandfollowed, and is now somewhat extensively engaged in the system; and other powers seem to emulate their example, though on a smaller scale.

Opinions differ amongst naval and scientific men as to the policy of adopting iron armature for ships-of-war. For coast and harbor defense they are undoubtedly formidable adjuncts to fortifications on land. As cruising vessels, however, we are sceptical as to their advantages and ultimate adoption. But whilst other nations are endeavoring to perfect them, we must not remain idle.

The enormous load of iron, as so much additional weight to the vessel; the great breadth of beam necessary to give her stability; the short supply of coal she will be able to stow in bunkers; the greater power required to propel her and the largely increased cost of construction, are objections to this class of vessels as cruisers which we believe it is difficult successfully to overcome. For river and harbor service we consider iron-clad vessels of light draught, or floating batteries thus shielded as very important; and we feel at this moment the necessity of them on some or our rivers and inlets to enforce obedience to the laws. We, however, do not hesitate to express the opinion, notwithstanding all we have heard or seen written on the subject, that no ship or floating battery, however heavily she may be plated, can cope successfully with a properly constructed fortification of masonry. The one is fixed and immovable, and though constructed of a material which may be battered by shot, can be covered, if need be, by the same or much heavier armor than a floating vessel can bear, whilst the other is subject to disturbances by winds and waves, and to the powerful effects of tides and currents.

Armored ships or batteries may be employed advantageously to pass fortifications on land for ulterior objects of attack, or run a blockade, or to reduce temporary batteries on the shores of rivers and the approaches to our harbors.

From what we know of the comparative advantages and disadvantages of ships constructed of wood over those of iron, we are clearly of opinion that no iron-clad vessel of equal displacement can be made to obtain the same speed as one not thus encumbered, because her form would be better adapted to speed. Her form and dimensions, the unyielding nature of the shield, detract materially in a heavy sea from the life, buoyancy, and spring which a ship built of wood possesses.

Wooden ships may be said to be but coffins for their crews when brought in conflict with iron-clad vessels; but the speed of the former, we take for granted, being greater than that of the latter, they can readily choose their position, and keep out of harm’s way entirely.

Recent improvements in the form and preparation of projectiles, and their increased capacity for destruction, have elicited a large amount of ingenuity and skill to devise means for resisting them in their construction of ships-of-war. As yet we know of nothing superior to the large and heavy spherical shot in its destructive effects on vessels, whether plated or not.

Rifled guns have greater range, but the conical shot does not produce the crushing effect of spherical shot.

It is assumed that 4 inch plates are the heaviest armor a sea going vessel can safely carry. These plates should be of tough iron, and rolled in large long pieces. This thickness of armor, it is believed, will resist all projectiles now in general use at a distance of 500 yards, especially if the ship’s sides are angular.

Plates hammered in large masses are less fibrous and tough than when rolled. The question whether wooden backing, or any elastic substance behind the iron plating will tend to relieve at all the frame of the ships from the crushing effect of a heavy projectile, is not yet decided. Major Barnard says “to put an elastic material behind iron is to insure its destruction.” With all difference to such elastic substance (soft wood, perhaps, is best) might relieve the frame of the ship somewhat from the terrible shock of a heavy projectile, though the plate should be fractured.

With respect to a comparison between ships of iron and those of wood, without plating, high authorities inEnglanddiffer as to which is best. The tops of ships built of iron, we are told, wear out three bottoms; whilst the bottoms of those built of wood will outwear three tops. In deciding upon the relative merits of iron and wooden-framed vessels, for each of which we have offers, the board is of opinion that it would be well to try a specimen of each as both have distinguished advocates. One strong objection to iron vessels which, so far as we know, has not yet been overcome, is the oxidation or rust in salt water, and their liability of becoming foul under water by the attachment of sea grass and animalcules to their bottoms. The best preventative we know of is a coating of pure zinc paint, which, so long as it lasts, is believed to be an antidote to this cause of evil.

After these brief remarks on the subject generally, we proceed to notice the plans and offers referred to us for construction of plated vessels and floating batteries.

It has long been suggested that the most ready mode of obtaining an iron-clad ship-of-war would be to contract with responsible parties in England for its complete construction; and we are assured that parties there are ready to engage in such an enterprise on terms more reasonable, perhaps, than such a vessels could be built in this country, having greater experience and facilities than we possess. Indeed, we are informed there are no mills and machinery in this country capable of rolling iron 4 inches thick, though plates might be hammered to that thickness in many of our workshops. As before observed, rolled iron is considered much the best, and the difficulty of rolling it increases rapidly with the increase of thickness. It has, however, occurred to us that a difficulty might arise with the British government, in case we should undertake to construct ships-of-war in that country, which might complicate their delivery; and moreover, we are of opinion that every people or nation who can maintain a navy should be capable of constructing it themselves.

Our immediate demands seem to require, first, so far as practicable, vessels invulnerable to shot, of light draught of water, to penetrate our shoal harbors, rivers and bayous. We, therefore, favor the construction of this class of vessels before going into a more perfect system of large iron-clad sea-going vessels of war. We are here met with the difficulty of encumbering small vessels with armor, which, from their size, they are unable to bear. We, nevertheless, recommend that contracts be made with responsible parties for the construction of one or more iron-clad vessels or batteries of as light a draught of water as practicable consistent with their weight of armor. Meanwhile, availing of the experience thus obtained, and the improvements which we believe are yet to be made by other naval powers in building iron-clad ships, we would advise the construction, in our own dock-yards, of one or more of these vessels upon a large and more perfect scale, when Congress shall see fit to authorize it. The amount now appropriated is not sufficient to build both classes of vessels to any great extent.