During the winter she was overhauled and enlarged, and her speed improved. In the spring of 1808 she resumed her regular trips, and since then steam navigation on the Hudson has not ceased for a single day, except during the closing of the river by ice.
In 1811 and 1812, Fulton built two steam ferry-boats for the North River, and soon after added a third for the East River. These boats were the beginning of the magnificent steam ferry system which is to-day one of the chief wonders of New York. They were what are called twin-boats, each of them consisting of two complete hulls, united by a deck or bridge. They were sharp at both ends, and moved equally well with either end foremost, so that they could cross and re-cross without being turned around. These boats were given engines of sufficient power to enable them to overcome the force of strong ebb tides; and in order to facilitate their landing, Fulton contrived a species of floating dock, and a means of decreasing the shock caused by the striking of the boat against the dock. These boats could accommodate eight four-wheel carriages, twenty-nine horses, and four hundred passengers. Their average time across the North River, a mile and a half wide, was twenty minutes.