USS Koka—a single-turreted, twin-screw

Propeller

A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

 monitor

Monitor (warship)

A monitor was a class of relatively small warship which was neither fast nor strongly armoured but carried disproportionately large guns. They were used by some navies from the 1860s until the end of World War II, and saw their final use by the United States Navy during the Vietnam War.The monitors...

—was launched 18 May 1865 by Wilcox & Whiting, Camden, NJ. She was a Casco-class, light-draft monitor intended for service in the shallow bays, rivers, and inlets of the Confederacy

Confederate States of America

The Confederate States of America was a government set up from 1861 to 1865 by 11 Southern slave states of the United States of America that had declared their secession from the U.S...

. These warships sacrificed armor plate for a shallow draft

Draft (hull)

The draft of a ship's hull is the vertical distance between the waterline and the bottom of the hull , with the thickness of the hull included; in the case of not being included the draft outline would be obtained...

 and were fitted with a ballast

Sailing ballast

Ballast is used in sailboats to provide moment to resist the lateral forces on the sail. Insufficiently ballasted boats will tend to tip, or heel, excessively in high winds. Too much heel may result in the boat capsizing. If a sailing vessel should need to voyage without cargo then ballast of...

 compartment designed to lower them in the water during battle.

Design revisions

Though the original designs for the Casco-class monitors were drawn by John Ericsson

John Ericsson

John Ericsson was a Swedish-American inventor and mechanical engineer, as was his brother Nils Ericson. He was born at Långbanshyttan in Värmland, Sweden, but primarily came to be active in England and the United States...

, the final revision was created by Chief Engineer Alban C. Stimers following Rear Admiral

Rear Admiral

Rear admiral is a naval commissioned officer rank above that of a commodore and captain, and below that of a vice admiral. It is generally regarded as the lowest of the "admiral" ranks, which are also sometimes referred to as "flag officers" or "flag ranks"...

 Samuel F. Du Pont's failed bombardment of Fort Sumter

Fort Sumter

Fort Sumter is a Third System masonry coastal fortification located in Charleston Harbor, South Carolina. The fort is best known as the site upon which the shots initiating the American Civil War were fired, at the Battle of Fort Sumter.- Construction :...

 in 1863. By the time that the plans were put before the Monitor Board in New York, NY

New York City

New York is the most populous city in the United States and the center of the New York Metropolitan Area, one of the most populous metropolitan areas in the world. New York exerts a significant impact upon global commerce, finance, media, art, fashion, research, technology, education, and...

, Ericsson and Simers had a poor relationship, also Chief of Naval Construction John Lenthall had little connection to the board. This resulted in the plans being approved and 20 vessels ordered without serious scrutiny of the new design. $14 million US was allocated for the construction of these vessels. It was discovered that Stimers had failed to compensate for the armor his revisions added to the original plan and this resulted in excessive stress on the wooden hull frames and a freeboard of only 3 inches. Stimers was removed from the control of the project and Ericsson was called in to undo the damage. He was forced to raise the hulls of the monitors under construction by 22 inches to make them sea-worthy.

Fate

As a result, the Navy Department

United States Department of the Navy

The Department of the Navy of the United States of America was established by an Act of Congress on 30 April 1798, to provide a government organizational structure to the United States Navy and, from 1834 onwards, for the United States Marine Corps, and when directed by the President, of the...

 suspended completion of the ship 17 June 1865, and she was laid up at League Island

League Island

League Island was an island in the Delaware River, part of the city of Philadelphia, just upstream from the mouth of the Schuylkill River, which was the site of the Philadelphia shipyard, which eventually became the Philadelphia Naval Shipyard, now known as the Philadelphia Naval Business...

 Navy Yard, Philadelphia, PA, without any active service. Renamed Argos 15 June 1869, she was again renamed Koka 10 August that same year. She was broken up at Philadelphia, PA, 2 October 1874, by Harlan & Hollingsworth Co., Wilmington, DE, for use in the construction of the .