Cargo means oil that is transported to and off-loaded at a destination by a vessel. It does not include -
(1) Oil carried in integral tanks, marine portable tanks, or independent tanks for use by machinery, helicopters, and boats carried aboard the vessel, or for use by helicopters that are directly supporting the vessel's primary operations; or
(2) Oil transferred from a towing vessel to a vessel in its tow to operate installed machinery other than the propulsion plant.
33 CFR § 155.1020
Except as otherwise defined in this section, the definitions in 155.110 apply to this subpart and subparts F and G of this part. For the purposes of this subpart only, the term: