Section 21
SEC. 21. Maritime Lien for Necessaries; persons entitled to such lien—Any person furnishing repairs, supplies, towage, use of dry dock or marine railway, or other necessaries to any vessel, whether foreign or domestic, upon the order of the owner of such vessel, or of a person authorized by the owner, shall have a maritime lien on the vessel, which may be enforced by suit in rem, and it shall be necessary to allege or prove that credit was given to the vessel.