What is a vessel? In maritime law, important rights and duties turn on whether something is a vessel. For example, the owner of a vessel can limit his liability for damages caused by the vessel under the Limitation of Shipowners’ Liability Act, and an injured seaman who is a member of the crew of a vessel can claim remedies under the Jones Act. Under the general maritime law, a vendor who repairs or supplies a vessel may acquire a maritime lien over the vessel. In these and other areas, vessel status plays a crucial role in setting the limits of admiralty jurisdiction. Clear boundaries are important because with admiralty jurisdiction comes the application of substantive maritime law—the specialized body of statutory and judge-made law that governs maritime commerce and navigation.