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The Design of America’s First Iron Steamboat

America’s First Iron Steamboat Marker (Located a short distance west of Wrightsville on the south side of Route 462, opposite Blessing Lane; 2015 Photo by S. H. Smith)
America’s First Iron Steamboat Marker (Located a short distance west of Wrightsville on the south side of Route 462, opposite Blessing Lane; 2015 Photo by S. H. Smith)

America’s First Iron Steamboat marker is located a short distance west of Wrightsville, York County, Pa., on the south side of Route 462, opposite Blessing Lane. It states, “The Codorus, built in York by John Elgar, was launched at present-day Accomac, on the Susquehanna River, Nov. 22, 1825. The site is about two miles distant.”

In 1824, a group of Baltimore businessmen wanted to test the practicality of running steamboats on the Susquehanna River. The rocky, steep swift flow at some places and wide shallows at other places, nature of the Susquehanna did not lend itself to the deeper draw, wood-hulled, steamboats that already traveled the relatively placid rivers in America, such as the Hudson River. The businessmen, many of whom were already associated with the Merchant Flouring Mills at York Haven in York County, advertised in Baltimore papers requesting proposals for a steamboat capable of navigating the erratic nature of the Susquehanna River.

Continue reading to discover how the design of America’s First Iron Steamboat evolved.


Since about 1820, John Elgar was associated with the well established firm, of Phineas Davis, Israel Gartner and James Webb, which operated a foundry and machine shop on the corner of West King and South Newberry Streets in York, Pa.; located less than a block from the Codorus Creek. John Elgar’s expertise was nail manufacturing; having already invented machinery to efficiently cut nails out of strips of iron, when he became associated with this firm at the age of 36.

The Baltimore backers accepted John Elgar’s innovative proposal to build an iron-hulled steamboat as the solution to create a high strength boat hull, with very shallow draw; the two key requirements needed to navigate the erratic Susquehanna River. John Elgar was in charge of designing and building the iron-hull of the first iron steamboat in America. Phineas Davis, who had prior experience with steam engines, took charge of the propulsion system for the steamboat.

Iron Plate from the Brandywine Rolling Mill

John Elgar likely proposed an iron-hulled steamboat because of his iron-working expertise and knowledge of where to obtain quality iron plate. The iron plate used to fabricate the iron-hull of The Codorus came from the Brandywine Rolling Mill in Coatesville, Pa. This facility began as the Brandywine Iron & Nail Factory and eventually became the huge Lukens Steel Mill. John Elgar’s original correspondence, dated March 31, 1825, with Dr. Charles Lukens, owner of the Brandywine Rolling Mill is now preserved in the collections of the Hagley Museum and Library, Wilmington, Delaware.

In this correspondence, John Elgar addresses Dr. Lukens as “Respected Friend,” and discusses the exacting nature of the iron required. Elgar states, “The iron to be of the best quality and sound, and particularly clear of buckles or bilges that prevent the sheet from lying flat.” The precise dimension of the iron plates and angle iron are spelled out. As a postscript to his letter, John Elgar notes, “Please return the gauge with the iron.” It is evident that Elgar supplied Lukens with an inspection gauge, for the mill to check the iron thickness; exhibiting the attention to detail that was required.

The Dimensions of The Codorus

The draw, i.e. the depth the iron steamboat would sit in water, had to be kept shallow, due to the many shallow areas; particularly in the upper branches of the Susquehanna River. The smallest draw is obtained with the largest boat footprint.

The 19-foot drop of the Conewago Falls on the Susquehanna River at York Haven could be navigated easily via the canal and locks, which opened in 1797. (See the post First Working Canal in Pennsylvania was in York Haven) The Conewago Canal locks were 80-feet long by 12-feet wide.

The dimensions of the Conewago Canal locks essentially set the footprint of The Codorus. Needing some distance to open lock gates and safety distances the 60-foot keel length was selected. A 9-foot beam, or width, allowed up to 18-inch wide paddle wheels on the sides.  If it had not been for the constraints of these locks, I suspect that Elgar would have selected a wider beam, to reduce the draw further, while increasing stability.

Folk artist Lewis Miller visited the Davis, Gartner, and Webb shops during the construction of The Codorus in 1825. Miller sketched the iron hull in the process of construction with the hull turned upside down and workmen busily riveting the iron plates to the angle iron framework.

No drawings of The Codorus have yet to surface. The correspondence with Dr. Lukens and newspaper descriptions from the voyages of The Codorus provide the only details. William S. Stair did the following drawing of The Codorus, based upon those details, for this illustration in the 1968 publication Greater York in Action, by The York Area Chamber of Commerce.

The Codorus, from a drawing by William S. Stair (Greater York in Action, by The York Area Chamber of Commerce, 1969; page 261)
The Codorus, from a drawing by William S. Stair (Greater York in Action, by The York Area Chamber of Commerce, 1969; page 261)

In 1825, the majority attitude was, “wood floated and iron sank, why would anybody build a boat out of iron?” However those individuals familiar with the work of Archimedes, knew an iron-hulled boat was possible.

Archimedes Principle

In designing his Iron Steamboat, it is obvious that John Elgar knew about the principle of buoyancy. His formal education consisted of no more than the third grade, however that did not keep him from being self taught; reading any book that he could get his hands on. Likely one of those books presented principles developed by the ancient Greek scientist Archimedes; one of which established that the buoyant force, i.e. upward force, of an object in a fluid is equal to the weight of the fluid displaced by the object.

The specific weigh of water is 62.4 pounds per cubic feet. The Codorus was 60-feet long and 9-feet wide. For every inch that The Codorus was immersed in water, it displaced 45-cubic-feet of water. The buoyance force per inch of immersion of The Codorus, per Archimedes Principle, is thus 62.4 x 45 = 2,808 pounds. The weight of The Codorus allows one to determine the draw; i.e. how shallow the iron steamboat would sit in water.

The boat hull was fabricated entirely of 1/12th-inch thick plate iron riveted to angle iron ribs spaced a foot apart. The whole weight of the iron-hull was 1,400 pounds. The weight of the deck, boathouse and supports for the power plant was an additional 2,600 pounds. The boiler, steam engine, and propulsion paddle wheels contributed another 4,000 pounds. When complete, the total weight of The Codorus was 8,000 pounds.

With typically 60 individuals on board, averaging 150 pounds each, that is another 9,000 pounds. A fully loaded Iron Steamboat Codorus thus weighed about 17,000 pounds, resulting in a very shallow draw of about 6-inches (6.054-inches x 2,808 pounds of buoyancy per inch of immersion of The Codorus = 17,000 pounds of buoyancy; to counteract the 17,000 pounds of weight attempting to sink the boat).

America’s First Iron Steamboat

On November 15, 1825, The Codorus was loaded on two large wagons that had been coupled together, for its journey to the Susquehanna River; at what is now known as Accomac in Hellam Township. John Edgar was busy the following week, getting the machinery installed.

On November 22, 1825, The Codorus was launched. She did not sink! Instead she operated flawlessly; traveling at a respectable six miles per hour against the current. The first iron steamboat in America went into the history books, owing to the vision of John Elgar.

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