S.C. Code Ann. § 54-15-120
(A) An apprentice in the Lower Coastal Area shall serve three years before being eligible to take an examination for the initial short branch license. During an apprenticeship, licensed pilots shall take an apprentice on board all types of vessels, so that the apprentice may become thoroughly competent for the discharge of piloting duties. An apprentice successively shall hold a:
(4) fourth branch license in service one year before being eligible to take an examination for a full license or branch.
The South Carolina Commissioners of Pilotage for the Lower Coastal Area shall establish in regulation the tonnages and draft restrictions for each short branch license.