Gibbs' rule no. 70; Keep digging 'til you hit bottom.
This was actually a rule that McGee mad up in the moment. Not an official Gibbs rule.
The Naval Vessel used in this show is DDG 79 USS Oscar Austin which is an Arleigh Burke-class destroyer (seen in the background when Gibbs boards the San Dominick.
Due to the length of the first act, the on-screen credits do not roll until the second act, which is uncommon for any TV series. This is the third time this has happened on NCIS (2003).
Jim Beaver who played Captain Tom O'Rourke in this episode, previously worked with Mark Harmon on Reasonable Doubts (1991).
If you look closely this is yet another episode where scenes "on board a US Navy ship" are spoiled by the use of plastic PVC pipe for set dressing.