The oldest known concrete ship was a dingy built by Joseph Louis Lambot in Southern France in 1848 and featured in the 1855 World's Fair. In the 1890s, an engineer in Italy named Carlo Gabellini built barges and small ships out of concrete; the most famous being the Liguria. On August 2, 1917, N.K. Fougner of Norway launched the first ocean-going concrete ship—an 84-foot-long boat named Namsenfjord. In the 1917, the Violette was built and currently is used as a boating clubhouse on the Medway River in England. This makes her the oldest concrete ship still afloat.
In 1917, the United State finally entered World War I and steel became scarce while the demand for ships went up. Businessman W. Lesie Comyn formed the San Francisco Ship Building Co., Oakland, Calif., to begin constructing concrete ships. The first American concrete ship, a steamer named the S. S. Faith, was launched March 18, 1918. She cost $750,000 to build. She was used to carry cargo for trade until 1921, when she was sold and scrapped as a breakwater in Cuba.
With the advent of World War II, the U.S. government contracted McCloskey & Co., Philadelphia, Pa., to construct a fleet of 24 concrete ships. Innovations in cement mixing and composition made these ships stronger than the previous attempts. After the war, several of the ships were turned into a floating breakwater in Canada and 10 more were sunk as a breakwater in Virginia. Source: Concreteships.org