Type B ship

The Type B ship is a United States Maritime Administration (MARAD) designation for World War II barges. Barges are very low cost to build, operate, and move, and can transport bulky cargo. Because barges lack engines for self-propulsion, they are usually moved by a tugboat, some classed as Type V ships. Once the barge is moved into position, the tugboat departs and can do another task. This means there is no immediate rush to load or unload the barge.

Toward the end of World War II, some ships that had not been completed in time for the war were converted into barges. US Navy water barges are given the hull classification symbols YWN or YW. Some barge classification symbols contain -N, indicating that the barge was not self-propelled. Due to the shortage of steel during World War II, concrete ship constructors were given contracts to build ferrocement barges for oil or gasoline, which were given the hull symbols YO, YOG, and YOGN; built in 1944 and 1945, some were named after chemical elements.