Riverboat Construction

 

In the beginnings of steamboating on America’s western frontier – which in the early years of the 19th century encompassed most of the continent west of Pittsburgh – the technology of the craft was new and uncertain. Robert Fulton and his partner, Nicholas J. Roosevelt, built the first steamboat on what would come to be called the Western Rivers at Pittsburgh in 1811. This little boat, New Orleans, managed to reach her namesake port early the next year, marking the inauguration of steam navigation on the Mississippi. By the time New Orleans was sunk on a snag near Baton Rouge in July 1814, several other boats were running on the river.

These early boats were little different from the small steamers that ran on the Hudson and the Delaware; New Orleans was reportedly very similar in design to Fulton’s North River Steam Boat, which is today more commonly known as Clermont. What the early boatmen discovered, though, was that those designs were poorly suited to the Mississippi and its tributaries, the Ohio, the Missouri, the Red and a hundred other streams. Their full-bodied hulls ran aground too often, they were too heavy, and their engines lacked the power necessary to stem the current of the Mississippi. Navigating the falls at Louisville or the horseshoe bends around Vicksburg, it turned out, was nothing like steaming on the Hudson.


Fulton’s North River Steamboat, better known today as Clermont.

But they adapted. Through the 1810s and 1820s, by trial and error, the steamboatmen systematically determined what worked and what didn’t. Boat builders experimented with all aspects of the craft, from hull form to cabin arrangement to the types of engines used. Gradually, very gradually, a series of features were settled upon that seemed to function most efficiently. Shallow, flat-bottomed hulls replaced deeper, rounded hulls. Machinery that had been situated inside the hull, below the boat’s deck, could no longer find a place there, and so ended up on the main deck, above the waterline. Passenger cabins that had been on the main deck now had to be relocated to a deck above – a deck that came to be called the boiler deck, even though the boilers themselves were situated below it. Sidewheels gradually moved from midships aft to a position about two-thirds back along the overall length of the vessel. Decks were extended outboard of the hull to enclose the sidewheels and provide additional space for cargo.

Guiding all these changes was the necessity to reduce weight, to allow the boat to draw as little water as possible. The earliest steamboats on the Western Rivers were mostly built in and around Pittsburgh. The construction of these boats generally followed forms developed on waterways of the Atlantic seaboard, due in part to the influx of shipwrights, carpenters and other craftsmen from ports on the east coast. Working at yards around Pittsburgh, and later at Louisville and Cincinnati, these craftsmen initially built what they knew best – rounded, deep-draft hulls, solidly timbered inside and out, that could stand the motion of a heavy sea. But these hull forms were heavy, drew a great deal of water, and were difficult to maneuver using the inefficient steam engines of the day. Over time, rounded bottoms gave way to flat ones, the ends of the boats became “sharper,” the better to cut through the water, and the boats became longer and narrower, with length-to-beam ratios of 5- or 6-to-1, much narrower than contemporary ocean-going vessels. Over time, the steamboat builders also largely abandoned the compound curves of marine hulls for hull forms that maintained the same cross-section for most of the boats’ length, greatly simplifying and speeding construction.

In addition to changes in hull form, the structure itself was made lighter by the use of increasingly smaller dimensions of timber. While the hulls of seagoing vessels derived their rigidity and strength largely through the use of heavy, closely-spaced timbers, each drawn out to an individual pattern and hewn to a precise curve, steamboat builders began relying on standard dimensions of lumber, with as much spacing left between the frames as they dared.


Archaeology volunteers examine the wreck of the former Buffalo Bayou steamer A. S. Ruthven, in the Trinity River near Palestine, Texas. The relatively small dimensions of the hull framing timbers are evident. Author’s photo.

These changes resulted in a buoyant, very light-draft hull, but they came at a price. The resulting hulls were light enough, but flimsy and prone to twisting. A particular problem was “hogging,” in which the ends of the vessel tend to sag while the middle section of the hull, the most buoyant part, retains its intended form. By the mid-1830s, just about the time steamboats were making their first, tentative attempts to ascend Buffalo Bayou, it had become clear that a different, or at least additional, approach was needed to improve the structural integrity of the hull. The answer proved to be a system of posts, called “braces,” running fore and aft, over which a series of wrought-iron rods, or “chains,” were arranged. These chains kept tension on either end of the hull, while the braces transmitted this stress more evenly along the hull of the boat. Between each pair of braces the chain was cut, threaded, and fitted with a simple turnbuckle that allowed the structure to be tightened or slacked off as needed. It was an elegant system, not unlike the structure of a truss bridge, lightweight and sturdy. Similar arrangements of “cross chains,” running across the ship from side to side, helped support the overhang of the main deck on either side of the boat, as well as the tremendous weight of the boat’s sidewheels.


Hogging chains running over braces on an early 20th century sternwheel towboat. Image via the Egregious Steamboat Journal.


 

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