What Submarine Am I?

["Allan E. Gaines" <exfloridians@ecsu.campuscwix.net>]

I was out flying around Puerto Rico with the Coast
Guard recently.  While out, we flew over a surfaced
submarine (several crewmembers were on deck).
It was black, with a conventional conning
tower.  However, it looked smaller than most U.S.
Navy subs I've seen.  Also, the stern "tail fins"
(what do you call them?)  *appeared* to be in an "x"
configuration.  What I mean is, if you
saw this sub from the rear, the tail fins would appear
as an "x" instead of a "+" like most subs I've seen.

[I presume it would look like an "x"; I don't know
what the fins below the water looked like.]