Hi,
we wrote own small VB6 parser for data from AIS receiver RS232 port to SQL Server 2005 Express database (1, 4, 5 messages) and join data as X, Y event theme in ArcMap.
We used last #1 message from ship for last ship's position.
Also we published ship position at ArcGIS Server as map and kml service.
You can use ITU1370 instruction for conversion formula.
Oleg Lukyanov
Russia