Typical of Great Lakes schooner construction in the late nineteenth century, the Oak Leaf's framing comprises double frame sets placed on 24-inch centers, with forward frame sets slightly larger than their aft partners. Individual frame pieces, or futtocks, are butt scarfed and fastened with iron pins. The keelson is supported down most of its length with a single rider sided at 9.0 inches and molded at 8.5 inches. There are no sister keelsons. An interesting method of longitudinal strengthening is, however, readily apparent.

Iron bracing runs along the keelson, counteracting the weight of the heavy cargo that often compromised the vessel's longitudinal strength. On the keelson's starboard side, an iron brace measuring 16.0 by 0.75 inches runs from just forward of the foremast to a few feet aft of the mizzenmast. The bracing is reinforced in two places with five 10-foot overlapping pieces the same width as the main brace. Each of these overlapping reinforcements is secured to the longer, primary reinforcing brace with 1.5-inch rivets. It appears that the primary brace possesses a slight, gradual arch, adding further to its strengthening capacity. This was probably added during the vessel's conversion to a stone barge, although it may be been part of the original construction.

The Oak Leaf's inner hull planking.

The Oak Leaf has virtually no deadrise or roundness to its hull and a very sharp turn of the bilge. It would have been virtually rectangular in full cross section. The hull was constructed to sacrifice sailing qualities for cargo capacity and a shallow draft, qualities that are generic to Great Lakes ships of the later half of the nineteenth century.