S.C. Code Ann. § 50-23-310: Numbering of vessels.

Every vessel using the waters of this State shall be numbered except those exempt by Section 50-23-320. No person shall operate or give permission for the operation of any such vessel on such waters unless the vessel is numbered in accordance with this chapter or in accordance with applicable Federal law or in accordance with a Federally-approved numbering system of another state and unless

(1) The certificate of number issued to such a vessel is on board and in full force and effect.

(2) The identifying number set forth in the certificate of number is displayed on each side of the forward half of the vessel.

(3) The decals issued by the department are attached to each side of the bow of the boat within six inches following the identifying number. Such decals, when a certificate of number is issued or renewed, shall be deemed a part of the registration number.