So the boats were CB90s of the Coastal Riverine Force....

via Defense Tech.

The U.S. Defense Department on Tuesday released photos showing the type of small Navy patrol boats that are being held by Iranian authorities, along with 10 U.S. crew members.
Two of the riverine boats drifted into Iran’s territorial waters in the Persian Gulf after one of the reportedly experienced mechanical problems while traveling from Kuwait to Bahrain. Rescue teams from the Harry S. Truman Strike Group — which includes the nuclear-powered aircraft carrier USS Harry S. Truman — responded, apparently too late, and remain in the vicinity.
A senior defense official confirmed the incident and said the crew members will be freed. But the statement didn’t specify when — one report indicated they may have to spend the night in Iran — or whether the vessels would also be returned.

Uh.  Wow.

So it was Riverines and not the Maritime Security bubbas.

The Riverines had fashioned themselves to be the "new" Naval Infantry.  They have been doing missions ashore and have trained with Dutch Marines.  Additionally they've been trying to (and with success) muscle themselves aboard amphibious ships, displacing US Marines because they were "Forward" and "Faithful".

But they surrendered without a shot?  I can't wait to read the after action on this one.