City Class Ironclad - City Class Gunboats; Pook Turtles

City Class Gunboats; Pook Turtles

In furtherance of Rodgers's orders, he and Eads drew up a set of requirements for a fleet of armored gunboats that would operate on the Mississippi. Rodgers knew, as his colleague did not, the characteristics that would be required for a successful war vessel. Eads's contribution was equally vital, as he knew the characteristics of boats that could operate on the Mississippi, and also how to assemble the industry to build them. Together, they decided that the gunboats should have adequate armor to withstand direct shot from the artillery of the day; speed sufficient to be able to move against the current; shallow draft; and enough guns to present a serious and credible threat to the enemy. Not stated but well understood was the necessity of providing adequate accommodations for the crew, who would likely be forced to fight inside the protective shell of armor in the heat of a Southern summer.

To assist in the design of a vessel that would satisfy all of these requirements, Rodgers called for help on John Lenthall, the head of the Navy Department's Bureau of Construction, Equipment, and Repair. Lenthall provided some preliminary plans, but he had to devote most of his attention to ocean-going ships, so he withdrew. Fortunately, he was able to provide a substitute. The Navy Department already had under contract a man who had experience in designing river craft, one Samuel M. Pook, working at the time in Cairo, Illinois.

Pook designed a vessel, or rather a set of vessels, that drew only six feet (1.9 meters) while carrying 13 guns. Capable of eight knots, each bore 2.5 inches (64 mm) of armor on the casemates and half that on the pilot house. In order to carry the machinery that would drive the great weight forward at speed while maintaining the light draft, the boats had to be made quite broad in relation to their length. Pook's solution was to give the hull three keels, the outboard pair somewhat longer than the one on the centerline. Propulsion was provided by a single paddle wheel at the after end of the center keel; the casemate armor that was carried back along the longer outboard keels provided the paddles a measure of protection from enemy gunfire from forward and abeam but not from astern. Each vessel as completed had a length overall of 175 feet (53 m) and a beam of 51 feet 2 inches (15.60 m). The length to beam ratio thus was a very small 3.4. The casemates had sloping sides, somewhat suggestive of the general shape of the best-known Confederate ship of the war, CSS Virginia (ex-USS Merrimack). When they were finally in the water, their awkward appearance struck the fancy of the farm boys who saw them, and they christened them "Pook's Turtles." The unofficial name stuck.

Eads submitted the winning bid for the contract to build seven boats to Pook's design. His bid was $89,600 per vessel, and he agreed to complete them by 10 October 1861. Because of changes in the design in the course of construction, the completion date was not met, and the cost more than doubled. By the end of January 1862, however, all had been delivered to the Army, where they were incorporated into the Western Gunboat Flotilla. The seven gunboats in the class were named for cities on the Mississippi or its tributaries. They were: USS Cairo, Carondelet, Cincinnati, Louisville, Mound City, Pittsburg, and St. Louis (later renamed Baron De Kalb). The first four of Eads's gunboats were built at the Carondelet Marine Ways (today part of St. Louis). This was a logical choice as St. Louis had the dry dock facilities, was a machinery center and had a ready supply of skilled tradesmen to do the required work. Most importantly, since the gunboats were to be used on the Mississippi River, building them at St Louis meant that at completion, the boat could be quickly put into service. This was 1861 and the thinking still was the war would be short. The three other gunboats were built at the Mound City Marine Railway & Shipyard facilities.