CPV code 63726400 designates Ship chartering services in the Common Procurement Vocabulary (CPV 2008), the EU classification used to describe the subject of public contracts.
63726400 is a leaf code — the most specific level of its branch — so it can be used directly as the main CPV code of a contract notice. If it does not quite fit, check the neighbouring codes under 63726000 (Miscellaneous water transport support services).