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The Warship That Couldn’t Stay Afloat

During the American Civil War, the Union Navy designed a class of warships called “Casco” that could submerge its hull at will to make the boat smaller and a harder target to hit. At least, that was the idea.
Until the middle of the 19th century, all ships, including warships, were made of wood. Steam-propelled, ironclad warships first saw action in the Battle of Hampton Roads, also known as the Battle of Ironclads. The Confederate fleet had one ironclad ram named Virginia, and on the Union side was the ironclad USS Monitor. While Virginia was built from the remnants of an under-construction steam frigate, the USS Monitor was built from grounds up and had a very unique design. The ship sat low in the water, with its deck barely above the water level rendering the warship nearly invisible. The deck was flush with the hull, and the only visible parts of the ship above the deck was the pilot-house and the revolving gun turret—another design innovation of the USS Monitor that eventually made its way into every modern battleship.
Battle of Hampton Roads
The first battle between the ironclads: CSS Virginia (left) and USS Monitor, during the Battle of Hampton Roads.
On March 9, 1862, the two ironclads met each other during the Battle of Hampton Roads. For four hours, the two ships repeatedly tried to ram one another while shells were fired at them from close range. In the end, neither won and both ships returned, slightly battered, but otherwise unharmed, to their respective ports.
The battle attracted attention all over the world, and gave rise to a new type of warship called the monitor. Engineer John Ericsson, who developed the original design for the Monitor, designed several new classes of monitors. The Passaic-class monitors were larger than the original Monitor and had their pilothouses atop the turret, rather than near the bow, which gave the turret a wider field of view. The Passaic monitors saw the most combats in the war and proved their worth far beyond the original contract price. A second class of monitors, called the Canonicus, were slightly longer but marginally narrower than the Passaic.
A third class of monitors, called the Casco-class, was developed specifically for operating along the shallow waters of the Mississippi River and it various tributaries. These vessels had a shallow draft—the portion of the hull under the water—of not more than six feet, and a freeboard—the portion of the hull above the water— of only fifteen inches. They were to be lightly armored compared to their larger cousins the Passaic and the Canonicus.
 the USS Monitor at sea
The USS Monitor at sea.
The original plans were drawn by John Ericsson, but they were altered by naval chief engineer Alban Stimers, who was woefully inexperienced to the task. Stimers wanted the ships to have an even lower draft, of only four feet, but at the same time he increased the armor on the decking and turret. Stimers also arranged the Cascos to have internal ballast tanks that could be flooded to lower the ships profile when going into battle. He also put an improved heavier engine. Ericsson tried to protest that the additional weight would make the ship sink, but with Stimers’ approval the Assistant Secretary of the Navy Gustavus Fox passed the plans and ordered twenty vessels to be built.
When the first completed vessel was put on sea trial, the deck sank below the water. To rectify the error, the hull was raised by an additional two feet, but it only added more weight to the already overweight vessel. Finally, the turret was removed and a torpedo was added. After several more trials it was concluded that the vessels were unseaworthy and completely useless. All twenty ships were scrapped. The fiasco cost the public $14 million in losses. Ericsson resigned even before the ships went into production. The Navy held Stimer responsible for the failure and had him reassigned.
the USS Casco on the James River,
The USS Casco on the James River, Virginia, 1865, while serving as a spar torpedo vessel.
Overall, the Casco class was a tremendous failure. The monitor itself wasn’t all that useful, and many felt that it was not a legitimate seagoing warship, especially with its shallow draft and low freeboard which made the vessels risky on the high seas.
After the American Civil War, monitors saw action during the Spanish–American War in 1898, and also during the two World Wars, when several monitor-type ships were used as support vessels. The last true monitor is the Parnaíba operated by the Brazilian Navy as part of their inland waterway force. First commissioned in 1938, the Parnaiba is the oldest warship still in service.
USS Shawnee and USS Wassuc

USS Shawnee and USS Wassuc, two Casco-class monitors laid up at the Boston Navy Yard, circa 1871-72.

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