537. You are in charge of a towing vessel that operates exclusively on inland waters. You regularly tow barges that provide services (cargo lighters, fuel barges, etc.) to foreign flag vessels in port. What will be accepted as proper credentials for you and your crew?

Merchant Mariner Credentials are required for U.S. towing vessels in commercial service, even on inland waters. State identification or Social Security cards are not substitutes, and operating solely on inland waters does not exempt the vessel from Coast Guard credentialing requirements.