A distinguishing characteristic developed on eastern North American steamboats during the 19th-century was the longitudinal sponson hull. On early side wheel steamers, the paddle wheels extended from the side of the hull with short guards. In the 1840's shipbuilders developed the sponson hull to utilize existing ship architecture to create more deck space. The main deck was carried out to the edge of the paddle guards and tapered in to meet the stem and stern. Angled braces fastened to the hull supported the overhanging guard from below. The sponson, or guard, often added twenty feet or more to the vessel's beam on the main deck depending on the width of the paddle wheels (Cuthbertson 1931:243-244; Russell 1861:108,113).
The section of guard examined during the 1993 investigation extended from 60 to 102 feet along the starboard side. This portion is forward of the paddle shaft and includes the forward half of the opening for the paddle wheel. For discussion this opening will be called the paddle box. The structure's general condition is very good but the entire guard has broken off the main hull. Deck beams that once extended from the side of the ship to support the guard have broken where they pass through the hull. As a result, the guard sags at a 10 to 15 degree angle (Figure 9A). The gap created by the break allowed a close examination of hull construction.
Deck beams support the guard which extends 9.6 feet from the side of the hull. Construction details, including the attachment of the guard beam, are covered by deck planks and were not examined. Deck construction is identical to the rest of the main deck. Planks measure 2 1/2 inches thick and average 6 inches wide. They are fastened with iron spikes set in counter sunk holes and capped with wooden plugs. Two fasteners were used on each deck beam and placed in a diagonal pattern.
Guards were normally supported underneath by diagonal bracing fastened to the hull (Cuthbertson 1931:244; Russell 1861:113). Diver safety precluded digging under the guard, therefore the type of bracing used on the Maple Leaf was not observed. The guard beam that marks the edge of the guard was recorded in the paddle box, as shown in Figure 9. The structure is 6 inches molded, 36 inches sided and composed of two horizontal timbers, one on top of the other. A wooden rub rail is fastened to the exterior side.
The large rectangular opening in the guard that contained the paddle wheel begins at 86 feet on the baseline. The inside width of the box is 8 feet 6 inches making the maximum width of the paddle wheel somewhat less. The end of the paddle shaft rested on an A-frame structure built on the outer edge of the guard (Figure 10). The paddle shaft support is centered 102 feet on the baseline, 16 feet from the forward edge of the paddle box. Doubling the measurement makes the paddle box 32 feet long, probably ending at 118 feet on the baseline.
The paddle shaft support was only examined on the forward half but is considered symmetrical in construction. It rises approximately 6 feet above main deck level on timber legs measuring 8 1/2 inches wide and 10 1/2 inches high. The top measures 13 1/4 inches wide by 6 feet 8 inches long, with a large, 34 inches long and 5 1/2 inches deep, square mortise in the center. This once held a bearing block to secure the end of the paddle shaft. The bearing block has been completely removed and the paddle shaft has been dislodged from its original position. This support provides the most reliable evidence of the shaft's original position along the length of the hull.