46 C.F.R. § 144.315 – Weight and moment history requirements for a vessel with approved lightweight characteristics.

(a) A weight and moment history of changes to the vessel since approval of its lightweight characteristics (displacement, Longitudinal Center of Gravity (LCG) and Vertical Center of Gravity (VCG)) must be maintained. All weight modifications to the vessel (additions, removals, and relocations) including a calculation of the aggregate weight change (absolute total of all additions, removals, and relocations) must be recorded in the history, along with a description of the change(s), when and where accomplished, moment arms, etc. After each modification, the lightweight characteristics must be recalculated.

(b) When the aggregate weight change is more than 2 percent of the vessel's approved lightweight displacement, or the recalculated change in the vessel's lightweight LCG is more than 1 percent of the LBP, a deadweight survey must be performed to determine the vessel's current lightweight displacement and LCG. Use the following table to determine when the deadweight survey results or the vessel's aggregate weight change requires the vessel to undergo a specified stability test:

Table 144.315
If—	Then—
(1) The deadweight survey results are both within 1 percent of the recalculated lightweight displacement and within 1 percent LBP of the recalculated lightweight LCG,	the recalculated lightweight VCG can be accepted as accurate;
(2) The deadweight survey results do not meet the criteria of paragraph (b)(1) of this section,	the vessel must undergo a stability test in accordance with 46 CFR 170, subpart F;
(3) The aggregate weight change is more than 10 percent of the vessel's approved lightweight displacement,	the vessel must undergo a stability test in accordance with 46 CFR 170, subpart F.