The requirements for Load Lines are based upon United States Code of Federal Regulations (CFR) 46 CFR 42.03-5, which states:

U.S.-flag vessels subject to the requirements of this subchapter.

(a) Vessels engaged in foreign voyages or international voyages other than solely Great Lakes voyages. (1) All U.S. flag vessels which engage in foreign voyages or international voyages by sea (other than solely in Great Lakes voyages) are subject to this part; except the following:

(i) Ships of war;

(ii) New vessels of less than 79 feet in length;

(iii) Existing vessels of less than 150 gross tons;

(b) Vessels engaged in domestic voyages by sea. (1) All U.S.-flag vessels which engage in domestic voyages by sea (coastwise and intercoastal voyages) shall be subject to the applicable provisions of this part except the following:

(i) Merchant vessels of less than 150 gross tons.