46 CFR § 136.215
Period of validity
April 15, 2021
(a) A COI for a towing vessel is valid for 5 years from the date of issue.
(b) For a towing vessel utilizing the TSMS option, the COI is invalid upon the expiration or revocation of the owner or managing operator TSMS certificate or the ISM Code Certificate.
(c) A COI may be suspended and withdrawn or revoked by the cognizant Officer in Charge, Marine Inspection at any time for noncompliance with the requirements of this subchapter.