Benjamin Franklin Isherwood



Occupation 1

Naval Architect

Occupation 2

Engineering Precedents


NA/Mid-Atlantic region


Age of Steam and Steel (1866-1920)








Marine engineer�

As the shift began from sail to steam, the Engineer Corps of the U.S. Navy was established in 1842, and it interested Isherwood as a new career. To gain the required experience on marine engines he worked for two years for the engine- and ship-building firm of Novelty Iron Works in New York City. In 1844 he received an appointment as first assistant engineer in the U.S. Navy� His promotion to chief engineer in 1849 finally made him a commissioned officer.

Charles B. Stuart, appointed civilian engineer in chief of the navy in 1850, promptly assigned Isherwood as his assistant in Washington, D.C. In a new design for the steamer Allegheny, Isherwood replaced the paddlewheels with a screw propeller and set the engines crosswise to the ship, with horizontal connecting rods from the pistons to the propeller shaft. The sea trials in 1853 were a failure because of inadequate bracing against the hull, which convinced Isherwood to design stronger framing in later work, but the system was considered a success. Known as the "Isherwood engine," it was much used during the Civil War. For the Water Witch he devised a new type of paddlewheel, the "Isherwood wheel," in which the paddles remained vertical for greater effectiveness and speed. This was the first use of the technique by the U.S. Navy�

As head of a board of engineers in 1860, Isherwood tested a range of values for the cutoff of piston stroke on the engine of the Michigan, operated for a month at constant speed with carefully measured coal and water. This established that the use of early cutoff of the steam injection distinctly lowered efficiency�

In March 1861 Isherwood was appointed engineer in chief of the U.S. Navy, just before the Civil War began. When ordered to remove the Merrimack from Gosport Navy Yard at Norfolk, Virginia, as that state threatened secession, Isherwood supervised the ship repairs at top speed. Then the commodore of the yard refused to let the ship sail, and after Isherwood's departure he scuttled all the ships. Confederate forces salvaged the Merrimack and built an ironclad vessel on its hull which faced the Union's Monitor in March 1862�

In a reorganization in 1863 Isherwood became the first chief of the Bureau of Steam Engineering, which was separated from the Bureau of Construction and Repair. Between 1861 and 1865 he designed machinery for forty-six paddlewheel vessels and seventy-nine screw steamers, with detailed specifications. His goal was to provide reliable and durable engines that could be operated by inexperienced personnel�

Criticism of Isherwood continued--from civilian engineers, from members of Congress, and from line officers who contended that large steam engines reduced space for sleeping quarters and that funnels interfered with sails. Isherwood was ousted as chief of the Bureau of Steam Engineering in 1869. He continued in the navy until his retirement in 1884, serving from 1869 to 1870 at Mare Island Navy Yard in California, where he conducted useful experiments on ship propellers. He then moved back to New York City, where he served on many engineering boards of investigation, and took a long tour in Europe. After retirement he received the rank of rear admiral. Isherwood died in New York City.

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Naval engineer and ship designer
Naval engineer and ship designer