The gross and net tonnage and dimensions of a vessel must be determined:

(a) For initial documentation;

(b) Whenever there is a change in the gross or net tonnage or dimensions of a documented vessel; or

(c) When the gross or net tonnage of a vessel returning to documentation has changed since the vessel was last documented.

(a) The gross and net tonnage and dimensions of a vessel for purposes of this part are determined in accordance with 46 CFR part 69.

(b) A certificate of measurement issued by an authorized official is the only acceptable evidence of the gross and net tonnage of a vessel measured in accordance with subpart B, C, or D of 46 CFR part 69. A certificate of measurement is not issued for vessels measured under subpart E of 46 CFR part 69 since the gross and net tonnage are determined as part of the documentation process.