46 C.F.R. § 140.605

(a) Prior to getting underway, and at all other times necessary to ensure the safety of the vessel, the master or officer in charge of a navigational watch must determine whether the vessel complies with all stability requirements in the vessel's trim and stability book, stability letter, COI, and Load Line Certificate, as applicable.

(b) A towing vessel must be maintained and operated so the watertight integrity and stability of the vessel are not compromised.