A platform supply vessel (PSV) is a ship specially designed to supply offshore oil and gas platforms. These ships range from in length and accomplish a variety of tasks. The primary function for most of these vessels is logistic support and transportation of goods, tools, equipment and personnel to and from offshore oil platforms and other offshore structures. In recent years, a new generation of platform supply vessels entered the market, usually equipped with Class 1 or Class 2 dynamic positioning system. They belong to the broad category of offshore vessels (OSVs) that include platform supply vessels (PSVs), crane vessels (CV) and well stimulation vessels (WSVs), anchor handling tug supply vessels (AHTSVs) and offshore construction vessels (OCVs). Larger offshore vessels have extensive sophisticated equipment including remotely operated underwater vehicles (ROVs) and tend to accommodate a larger number of people (more than 100). Capabilities Cargo A primary function of a platform supply vessel is to transport supplies to the oil platform and return other cargoes to shore. Cargo tanks for drilling mud, pulverized cement, diesel fuel, potable and non-potable water, and chemicals used in the drilling process comprise the bulk of the cargo spaces. Fuel, water, and chemicals are almost always required by oil platforms. Certain other chemicals must be returned to shore for proper recycling or disposal, however, crude oil product from the rig is usually not a supply vessel cargo. Support Common and specialty tools are carried on the large decks of these vessels. Most carry a combination of deck cargoes and bulk cargo in tanks below deck. Many ships are constructed (or re-fitted) to accomplish a particular job. Some of these vessels are equipped with a firefighting capability and fire monitors for fighting platform fires. Some vessels are equipped with oil containment and recovery equipment to assist in the cleanup of a spill at sea. Other vessels are equipped with tools, chemicals and personnel to "work-over" existing oil wells for the purpose of increasing the wells' production. Vessel types Platform supply vessels (PSV): High capacity supply ship, either in deck or cargo hold. Anchor handling tugs supply (AHTS): Similar to PSV, they can anchor and tow floating oil platforms (jack-ups and semi-submersible ones) Multi purpose supply vessels (MPSV): Universal vessels able to provide a large variety of maintenance services. They are most of the time equipped with a high capacity crane (100 tons and more). "Jumpers", particular MPSV