I don't usually see military ships sending an AIS signal, but a couple of
days ago I monitored (from my house) the USS John C. Stennis, a Nimitz-class
nuclear-powered aircraft carrier ( http://www.cvn74.navy.mil/ ). The
Stennis was steaming north, about 60NM offshore of San Francisco, on her way
to her home port of Bremerton, Washington. The Stennis has just completed
service in the Mideast. I sent her some "welcome home" email, and got a
nice reply from her navigator. The Stennis arrived in Bremerton yesterday.

The AIS data was interesting:
---------
Name: AIRCRAFT CARRIER 74
Position at 08/29/2007 21:40:24
MMSI: 111111111
Call: NJCS
Type: reserved, No additional information
Length: 1,115.5 ft
Beam: 255.9 ft
Draft: 40.0 ft
Destination:
SOG: 21.8 Kt, COG: 326.6° T
---------

That MMSI has to be "non-standard". I saw the name, did some googling, and
discovering that the Stennis is "CVN 74", which indicates (from Wikipedia):
---
The Nimitz-class supercarriers are a line of nuclear-powered aircraft
carriers in service with the US Navy, and are the largest capital ships in
the world. These ships are numbered with consecutive hull numbers starting
with CVN 68. The letters "CVN" denote the type of ship: CV is the hull
classification symbol for Aircraft Carriers, and N to indicate
nuclear-powered propulsion. The number after the "CVN" means that this is
the 68th "CV", or aircraft carrier.
---

I do wonder what the Navy policy on AIS is. You may have seen my posting
back in April, about receiving AIS and corresponding via email with the
SBX-1 Sea-Based X-Band Radar -- a floating, self-propelled, mobile radar
station designed to operate in high winds and heavy seas.

-Paul