Harlan & Hollingsworth's experience with railcars and other ironwork led them to become early experimenters in iron shipbuilding. In 1842 the company hired Alexander Kelly to supervise all the millwright work. In 1843, under the encouragement of Samual Harlan, the company started engaging in marine engine building and repair. Their first ship-related project was repairing the cylinder and other machine parts of the steamboat "Sun". This small step was the beginning of what would become one of the first iron shipyards in the United States.