Riveting and caulking a watertight iron hull

Rivets join hull members and provide strength, but many joints must also keep water or oil out. Closely spaced rivets and good workmanship can produce a tight joint, with rust between the faying surfaces filling remaining gaps over time. Caulking adds a seal by displacing metal at the plate edges where workmanship or rivet spacing alone is insufficient. The text gives a maximum spacing of roughly 3.5 to 5 rivet diameters for watertight work; the explanation explicitly corrects an initial reference to plate dimensions. Lighter plating needs closer relative spacing because it can yield under the tool and lose its seal when strained. Splitting and setting tools form an edge shoulder held against the adjoining plate by elasticity. Butt caulking forces prepared plate edges together, with a fuller used where the surfaces do not make good contact.