USS Monitor - Design and Construction

Design and Construction

Designed by the Swedish engineer and inventor John Ericsson, Monitor was described as a "cheesebox on a raft," consisting of a heavy round revolving iron gun turret on the deck, housing two 11 in (280 mm) Dahlgren guns side by side. The original design used a system of heavy metal shutters to protect the gun ports while reloading. However, the operation of the shutters proved so cumbersome, the gun crews simply rotated the turret away from potential hostile fire to reload. Further, the momentum of the rotating turret proved to be so great that a system for stopping the turret to fire the guns was implemented on later ships of the type. Monitor's gunners solved the turret momentum problem by firing on the fly while the turret rotated past the target. While this procedure resulted in a substantial loss of accuracy, this was not critical, given the close range at which Monitor operated.

The armored deck was only 18 in (460 mm) above the waterline. Aside from the turret, a small boxy pilothouse, a detachable smokestack and a few fittings, the bulk of the ship was below the waterline to prevent damage from cannon fire. The turret comprised eight layers of 1 in (25 mm) plate, bolted together, with a ninth plate inside to act as a sound shield. A steam donkey engine turned the turret. The heavily armored deck extended beyond the waterproof hull, only 5⁄₈ inches (16 mm) thick. The vulnerable parts of the ship were completely protected, as was proved during her battle with the Virginia during the Battle of Hampton Roads: the Virginia's shot bounced off of Monitor's turret and deck, sometimes denting them but never breaching them. These dents can be seen today on the recently recovered turret. The only weak spot proved to be the pilothouse, both due to its location relative to the turret (poor aim on the part of Monitor's gunners would cause them to strike their own pilothouse) and in or near its viewing slot, which, along with one of the iron beams that reinforced the pilothouse, was smashed by an exploding shell.

Monitor's hull was built at the Continental Iron Works in the Greenpoint section of Brooklyn, New York, and the ship was launched there on 30 January 1862. The innovative vibrating lever, or half-trunk, steam engines, designed by John Ericsson, and machinery were constructed at the DeLamater Iron Works in Manhattan, The boilers and engines were installed dead aft.

Monitor was innovative in construction technique as well as design. Parts were forged in nine foundries and brought together to build the ship; the whole process took less than 120 days. Portions of the heavy iron armor plating for the vessel were made at a forge in Clintonville, New York. In addition to the "cheesebox", its rotating turret, Monitor was also fitted with Ericsson's novel marine screw, whose efficiency and reliability allowed her to be one of the first to rely exclusively upon steam propulsion. Monitor had an unusually low 18 in (460 mm) freeboard, with the pilothouse and turret being the only permanent protrusions from the deck. Though this low freeboard greatly reduced the Monitor's vulnerability to gunfire compared to other naval vessels of the day, it also greatly reduced the ship's seakeeping capabilities.

Monitor was also noteworthy for her social architecture. Unlike other ships of the time, in which common sailors slept near the bow, with those of increasingly higher rank being found as one worked back to the captain's cabin in the stern, on the Monitor the captain's cabin was in the bow, followed by his officers and then the berth deck, where the junior officers, engineers, and sailors slept.