46 CFR §42.20-13

1. (a)A lighter, barge, or other vessel without independent means of propulsion is assigned a freeboard in accordance with the provisions of this subpart as modified by paragraphs (b), (c), and (d) of this section.
2. (b)A barge that meets the requirements of § 42.09-5(b) may be assigned Type “A” freeboard if the barge does not carry deck cargo.
3. (c)An unmanned barge is not required to comply with § 42.15-75, § 42.15-80(b), or § 42.20-70.
4. (d)An unmanned barge that has only small access openings closed by watertight gasketed covers of steel or equivalent material on the freeboard deck, may be assigned a freeboard 25 percent less than that calculated in accordance with this subpart.