Concrete ships are ships
built of steel and
ferrocement (
reinforced concrete) instead of more traditional materials, such as steel or wood. The advantage of ferrocement construction is that materials are cheap and readily available, while the disadvantages are that construction labor costs are high, as are operating costs. (Ferrocement ships require thick hulls, which means extra mass to push and less space for cargo.) During the late 19th century, there were concrete river barges in Europe, and during both
World War I and
World War II, steel shortages led the US military to order the construction of small fleets of ocean-going concrete ships, the largest of which was the
SS Selma. Few concrete ships were completed in time to see wartime service during World War I, but during 1944 and 1945, concrete ships and barges were used to support U.S. and British invasions in Europe and the Pacific. Since the late 1930s, there have also been ferrocement
pleasure boats.