page_title: John Lenthall (shipbuilder)
section_title: Philadelphia Navy Yard
hierarchical_section_title: John Lenthall (shipbuilder) / Career / Philadelphia Navy Yard
caption_attribution_description: Original caption read: Photo # NH 325 USS Decatur "Beating round 'Cape Freward': Straits of Magellan, Dec: 1854"
context_page_description: John Lenthall was an important American shipbuilder and naval architect. He was responsible for the construction and repair of United States Navy ships during the American Civil War, as well as in the years immediately before and after it. His career spanned the U.S. Navy's transition from sail to steam propulsion and from wooden ships to ironclads, and in retirement he participated in early planning for an eventual steel navy.
context_section_description: Around 1827, Lenthall became the apprentice of Samuel Humphreys; Humphreys had become Chief Constructor of the Navy in 1826 while retaining his position as the Naval Constructor at the Philadelphia Navy Yard in Philadelphia, Pennsylvania, where he continued to spend most of his time. Humphreys took on all the design work at the navy yard himself, and Lenthall worked closely with him and excelled as his assistant and draftsman. Lenthall also was exposed to the work of the noted naval architect William Doughty.
  Humphreys nominated Lenthall to become an assistant naval constructor at the Philadelphia Navy Yard in 1828. With Humphreys monopolizing naval ship design, Lenthall and his fellow constructors and assistant constructors occupied at least some of their time with designing merchant ships, and papers survive from the Philadelphia shipbuilding firm of John Lenthall and Company.
  Various sources state that Lenthall "entered" the U.S. Navy on 1 May 1835, but none provide any further information on any career he had as a naval officer. He continued to work mainly at the Philadelphia Navy Yard through the 1830s and 1840s, and by about 1860 was referred to as a civilian employee of the Navy and as "Mr. Lenthall," so any career he had in uniform appears to have ended by that time.
  Surviving papers from the 1830s demonstrate that Lenthall was well informed about the latest ship design theories of the era and used extensive calculations in his design work. Under his superintendence at Philadelphia the first American first-rate ship-of-the-line, USS Pennsylvania, was completed and the  supply ship USS Relief was built. He was promoted from assistant naval constructor to naval constructor on 21 July 1838, and in that year he appears to have been solely responsible, albeit in consultation with Humphreys, for the design of a particularly handsome and popular class of sloops-of-war made up of USS Decatur, USS Dale, USS Marion, USS Preble, and USS Yorktown. He also continued his commercial endeavors, designing ships for Philadelphia merchants, including packet ships for the  famous Cape Line. In the early 1840s he completed his efforts to refine the plans of the sailing frigate USS Raritan, laid down in 1820 but not launched until 1843, and she emerged as a speedy ship for her day. In the mid-1840s he designed the sloop-of-war USS Germantown, renowned as a fast sailer, particularly in light winds.
caption: USS Decatur.
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