46 CFR §69.153

1. (a)If a vessel is assigned two gross register tonnages under § 69.175(b), the higher gross register tonnage is the tonnage used when applying inspection, manning, and load line laws and regulations to the vessel.
2. (b)Tonnage marks are not to be construed as additional load line marks. Whether or not a tonnage mark is submerged under § 69.171 has no effect on the applicability of load line laws and regulations.