46 CFR 144.315: Weight and moment history for approved lightweight vessels

Last reviewed: October 14, 2026

A vessel with approved lightweight characteristics must keep a weight and moment history of all weight changes. Lightweight characteristics must be recalculated after each modification. Certain weight or LCG changes trigger a deadweight survey, and some results or changes trigger a stability test.

Applies toA vessel with approved lightweight characteristics (displacement, LCG and VCG).

What it says

  1. The vessel must maintain a weight and moment history of changes since approval of its lightweight characteristics.

    46 CFR 144.315(a)“A weight and moment history of changes to the vessel since approval of its lightweight characteristics”

  2. All weight additions, removals and relocations must be recorded in the history, including a calculation of the aggregate weight change, a description of the change, when and where it was done, and moment arms.

    46 CFR 144.315(a)“All weight modifications to the vessel (additions, removals, and relocations) including a calculation of the aggregate weight change”

  3. The lightweight characteristics must be recalculated after each modification.

    46 CFR 144.315(a)“After each modification, the lightweight characteristics must be recalculated.”

  4. A deadweight survey must be performed when the aggregate weight change is more than 2 percent of the approved lightweight displacement, or the recalculated change in lightweight LCG is more than 1 percent of the LBP.

    46 CFR 144.315(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”

  5. If the deadweight survey results are 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.

    46 CFR 144.315(b)(1)“the recalculated lightweight VCG can be accepted as accurate;”

  6. If the deadweight survey results do not meet the criteria of paragraph (b)(1), the vessel must undergo a stability test in accordance with 46 CFR 170, subpart F.

    46 CFR 144.315(b)(2)“the vessel must undergo a stability test in accordance with 46 CFR 170, subpart F;”

  7. If the aggregate weight change is more than 10 percent of the approved lightweight displacement, the vessel must undergo a stability test in accordance with 46 CFR 170, subpart F.

    46 CFR 144.315(b)(3)“The aggregate weight change is more than 10 percent of the vessel's approved lightweight displacement,”

Common questions

When is a deadweight survey required?

A deadweight survey must be performed when the aggregate weight change is more than 2 percent of the approved lightweight displacement, or the recalculated lightweight LCG change is more than 1 percent of the LBP.

“a deadweight survey must be performed to determine the vessel's current lightweight displacement and LCG.”

When must a vessel undergo a stability test?

A vessel must undergo a stability test if the deadweight survey results do not meet the criteria of paragraph (b)(1), or if the aggregate weight change is more than 10 percent of the approved lightweight displacement.

“The aggregate weight change is more than 10 percent of the vessel's approved lightweight displacement,”

What counts as aggregate weight change?

Aggregate weight change is the absolute total of all additions, removals, and relocations.

“(absolute total of all additions, removals, and relocations)”

The text of 46 CFR 144.315

Electronic Code of Federal Regulations (eCFR), current as of April 16, 2026 · Read it on eCFR

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.

Sections it refers to

  • 46 CFR 170, subpart F

The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of April 16, 2026. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.