Naval Architecture Analysis of Civil War Ironclad CSS VIRGINIA

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Virginia Tech

This thesis presents the results of a naval architecture analysis of the Civil War Ironclad CSS Virginia, built by the Confederate States Navy to break the Union Blockade of Hampton Roads, and which famously engaged the USS Monitor on the second day of the Battle of Hampton Roads, March 9th, 1862.

The purpose of the analysis was to examine the ship from a naval architectural standpoint pertaining to hydrostatics, stability, weight and center of gravity, sea keeping, and basic resistance/powering requirements. The overall objective was to see if the story of the CSS Virginia, destroyed on May 11th, 1862 by its own crew to keep it from falling into Union hands, could have ended differently with an attack on Washington, a northern city such as New York or Boston, or a run to a friendly Southern port such as Savannah or Charleston.

Paramarine software was used to build a geometry model based on lines included in a book by Sumner B. Besse for ship modelers. The geometry model provided the basic measures of displacement for the hull form at a draft of 21 ft forward and 22 ft aft which in turn allowed for a weight estimate to be undertaken. The goal of the weight estimate was to obtain, in particular, an estimate for the VCG of the vessel. It also allowed for gyradius calculations based on the resultant weight distribution to be calculated. Historical information coupled with the Paramarine geometry was used for the weight analysis.

Paramarine was used to obtain Random Amplitude Operators (RAOs) for a sea keeping analysis and long term effectiveness ratings considering MSI and Deck Wetness criteria were obtained based on statistical wave data from NOAA taken from stations in the Chesapeake Bay and in the Atlantic, 64 miles east of Virginia Beach.

A NAVCAD analysis was made for resistance requirements, though any resistance analysis of such an antiquated hull form that is also in its way unique has large uncertainties associated with it.

The results of the analysis shed some light on the CSS Virginia and its history.

The hydrostatic analysis leads one to speculate that draft reduction efforts made to allow the Virginia to escape Union capture by sailing up the James River were known to be hopeless, but undertaken anyway to save the honor of those involved and shift blame for the loss of the ship elsewhere.

The resistance and powering analysis suggests that an upper speed of 6 knots was probably not outside the CSS Virginia's capabilities. Speeds much higher seem unlikely. The only way to know more would be to get better estimates of power provided by the ship's steam engines and do a tow tank test of a ship model. Assuming a speed of 6 knots and based on a coal consumption rate, it was found that range of the CSS Virginia was at best around 614 nautical miles, giving it the distance to attack New York or sail to Charleston or Savannah.

However, the sea keeping analysis shows that the Virginia was very much at home on the relatively calm waters of the Chesapeake Bay, but would have run great risks in sailing on the open sea either to attack a Northern city or make a run to the South for safer waters to fight another day. The officers of the Virginia felt that the ship was likely to flounder; based on the deck wetness criteria chosen for the sea keeping analysis their professional judgment was correct.

Details of the weight analysis and a full set of RAOs are provided in the Appendices.

Ironclad, Naval Architecture