Battle of Johnsonville - Historical Background

The Sidewheeler and the Sternwheeler

The vessels sunk at Johnsonville, whether tinclad or transport, were either a western-rivers sidewheeler or sternwheeler, both designs "famed for an extraordinary cargo capacity in relation to draft" (Hunter 1949:72). While the first steamboats in the west did not differ much structurally from seagoing vessels, over a period of 30 years a vast technical change occurred, adapting the steamboats to the natural and economic conditions of travel along the Mississippi River system. To adapt steamboats to the natural constraints of the western rivers, they were increased in length and breadth of hull, and decreased in depth. In the late 1820s, experimentation with lighter methods of hull construction began, and by the 1840s hull lines had become rectangular throughout, with a flat bottom and straight sides, and with curved surfaces of the hull largely confined within the short distances of the bow and stern (Hunter 1949:77, 80).

In the late 1840s and early 1850s, the western steamboat assumed the lines historically associated with the western river. In the sidewheeler, length and paddle wheel size increased. Chimneys and the larger pilot house sat farther aft. The stacks passed up through the superstructure instead of directly forward of it. The extended, narrow flat-bottomed hull, a typical design feature of the western steamer, provided greater underwater stability and reduced listing tendencies, a feature crucial for steam power plant operation. Besides stability, the cost of building a straight-lined hull with flat surfaces paled in comparison to the sheered lines of a sailing ship. On the whole, the vessel lost the cumbersome appearance typical of early steamboats. By 1860 hulls measured less than 40 feet across, and after 1860 widened to less than 60 feet (Pearson et al. 1996:10). Steamboat plans from 1850 to 1880 indicate a consistent increase in hull length, width, and shallowness.

Similar to the changes in vessel hulls, the propulsion system was changing from low-pressure, condensing engines to high-pressure, non-condensing ones. Low-pressure engines, although safer and more fuel efficient, were replaced with high-pressure engines that were much faster and more easily maneuvered under diverse navigational conditions, such as variable water depths ranging from one to 50 feet, and differing current speeds. These engines were powered by long, horizontal, internal flue boilers. However, the major hazard associated with the high-pressure engines was boiler explosion, a common occurrence. These explosions were the greatest cause of death from steamboat accidents on the western rivers (Donovan 1966; Duay 1992:33-34; Hunter 1949:121-180).

Profile and main deck plan of an 1850s sidewheeler (as presented in Sawyer 1978:74).

The typical 1850s western-rivers steamboat was a flat-bottomed, shallow-drafted sidewheeler. Four-fifths out of the water, the fully-developed sidewheeler had three decks. The main deck covered and extended beyond the hull over the water as "guards." Above the main deck was the boiler deck; it was much narrower, housing passenger and state rooms. Above the boiler deck were the hurricane and Texas decks and the pilot house (Hunter 1949:90-91).

Used infrequently except on small vessels until after the Civil War, sternwheeler propulsion replaced sidewheeler in the post-bellum decades due to "(1) the removal of the paddle-wheel from its recess in the stern; (2) the application of two engines to cranks fixed at right angles to each other at opposite ends of the paddle-wheel shaft; (3) the incorporation of the paddle-wheel assembly in the hog-chain system; and (4) the introduction of the multiple balance rudder" (Hunter 1949:172-173). Cheaper to build and more effective in low water than sidewheelers and thus more economical, the sternwheeler had established itself as the dominant vessel type on the western rivers by 1880.

Profile and plan view of a mid-nineteenth century sternwheeler (as presented in James and Pearson 1993:13).


The vessels sunk at Johnsonville, whether tinclad or transport, were either a western-rivers sidewheeler or sternwheeler, both designs "famed for an extraordinary cargo capacity in relation to draft" (Hunter 1949:72). While the first steamboats in the west did not differ much structurally from seagoing vessels, over a period of 30 years a vast technical change occurred, adapting the steamboats to the natural and economic conditions of travel along the Mississippi River system. To adapt steamboats to the natural constraints of the western rivers, they were increased in length and breadth of hull, and decreased in depth. In the late 1820s, experimentation with lighter methods of hull construction began, and by the 1840s hull lines had become rectangular throughout, with a flat bottom and straight sides, and with curved surfaces of the hull largely confined within the short distances of the bow and stern (Hunter 1949:77, 80). In the late 1840s and early 1850s, the western steamboat assumed the lines historically associated with the western river. In the sidewheeler, length and paddle wheel size increased. Chimneys and the larger pilot house sat farther aft. The stacks passed up through the superstructure instead of directly forward of it. The extended, narrow flat-bottomed hull, a typical design feature of the western steamer, provided greater underwater stability and reduced listing tendencies, a feature crucial for steam power plant operation. Besides stability, the cost of building a straight-lined hull with flat surfaces paled in comparison to the sheered lines of a sailing ship. On the whole, the vessel lost the cumbersome appearance typical of early steamboats. By 1860 hulls measured less than 40 feet across, and after 1860 widened to less than 60 feet (Pearson et al. 1996:10). Steamboat plans from 1850 to 1880 indicate a consistent increase in hull length, width, and shallowness. Similar to the changes in vessel hulls, the propulsion system was changing from low-pressure, condensing engines to high-pressure, non-condensing ones. Low-pressure engines, although safer and more fuel efficient, were replaced with high-pressure engines that were much faster and more easily maneuvered under diverse navigational conditions, such as variable water depths ranging from one to 50 feet, and differing current speeds. These engines were powered by long, horizontal, internal flue boilers. However, the major hazard associated with the high-pressure engines was boiler explosion, a common occurrence. These explosions were the greatest cause of death from steamboat accidents on the western rivers (Donovan 1966; Duay 1992:33-34; Hunter 1949:121-180). Profile and main deck plan of an 1850s sidewheeler (as presented in Sawyer 1978:74). The typical 1850s western-rivers steamboat was a flat-bottomed, shallow-drafted sidewheeler. Four-fifths out of the water, the fully-developed sidewheeler had three decks. The main deck covered and extended beyond the hull over the water as "guards." Above the main deck was the boiler deck; it was much narrower, housing passenger and state rooms. Above the boiler deck were the hurricane and Texas decks and the pilot house (Hunter 1949:90-91). Used infrequently except on small vessels until after the Civil War, sternwheeler propulsion replaced sidewheeler in the post-bellum decades due to "(1) the removal of the paddle-wheel from its recess in the stern; (2) the application of two engines to cranks fixed at right angles to each other at opposite ends of the paddle-wheel shaft; (3) the incorporation of the paddle-wheel assembly in the hog-chain system; and (4) the introduction of the multiple balance rudder" (Hunter 1949:172-173). Cheaper to build and more effective in low water than sidewheelers and thus more economical, the sternwheeler had established itself as the dominant vessel type on the western rivers by 1880.

Profile and plan view of a mid-nineteenth century sternwheeler (as presented in James and Pearson 1993:13).