By 1849 the shipping industry was in transition from sail-powered boats to steam-powered boats and from wood construction to an ever-increasing metal construction. There were basically three different types of ships being used: standard sailing ships of several different types. Clippers, and paddle steamers with paddles mounted on the side or rear. River steam boats typically used rear mounted paddles and had flat bottoms and shallow hulls designed to carry large loads on generally smooth and occasionally shallow rivers. Ocean-going paddle steamers typically used side-wheeled paddles and used narrower deeper hulls designed to travel in the often stormy weather encountered at sea. The ship hull design was often based on the clipper ship design with extra bracing to support the loads and strains imposed by the paddle wheels when they encountered rough water.