Demologos: an early steam-powered floating battery

The Demologos, also called Fulton, is described as a steam-powered harbour-defence floating battery rather than a practical ocean-going ship. Its catamaran hull placed the paddlewheel between the hulls, an arrangement that helped protect the machinery but did not solve its operational limitations. The U.S. Navy considered more vessels but faced the awkward fact that they could not make ocean passages and would have to be built locally for each defended harbour. The example shows that a new propulsion technology could appear long before navies found a mature military use for it.