Is C-Retriever a U.S. Flag Vessel?

All the news reports are saying the C-Retriever is a U.S. Flag Vessel (the Captain and Chief
Engineer were kidnapped off of it and taken to Nigeria).

But....I cannot find this vessel listed on the MARAD web-site as a U.S. Flag Vessel.

Click here for the link to the list

Furthermore, unless something has changed, U.S. Flag Vessels must have an
entirely American Crew,  not just the Captain and Chief Engineer.

So what's the real story behind the C-Retriever?.

I think there is something funny going on.

Let me know what you think.