46 CFR §136.105

1. (a)This subchapter is applicable to all U.S.-flag towing vessels as defined in § 136.110 engaged in pushing, pulling, or hauling alongside, except—
   1. (1)A vessel less than 26 feet (7.92 meters) in length measured from end to end over the deck (excluding the sheer), unless that vessel is pushing, pulling, or hauling a barge that is carrying oil or hazardous material in bulk;
   2. (2)A vessel engaged in one or more of the following:
      1. (i)Assistance towing as defined in § 136.110;
      2. (ii)Towing recreational vessels for salvage; or
      3. (iii)Transporting or assisting the navigation of recreational vessels within and between marinas and marina facilities, within a limited geographic area, as determined by the local Captain of the Port (COTP);
   3. (3)A workboat operating exclusively within a worksite and performing intermittent towing within the worksite;
   4. (4)A seagoing towing vessel of 300 gross tons or more subject to the provisions of subchapter I of this chapter;
   5. (5)A vessel inspected under other subchapters of this chapter that may perform occasional towing;
   6. (6)A public vessel as defined in 46 U.S.C. 2101;
   7. (7)A vessel that has surrendered its COI and is laid up, dismantled, or otherwise out of service; and
   8. (8)A propulsion unit used for the purpose of propelling or controlling the direction of a barge where the unit is controlled from the barge, is not normally manned, and is not utilized as an independent vessel.
2. (b)[Reserved]