Disappearing AIS targets

[Jim.Pope]

After more careful review, I do not have problems with AIS targets disappearing inappropriately. My problem is that AIS Class B targets are not being displayed on my e125 connected to N2K network. Class A targets display as expected. Both Class A & B targets are displayed on a PC running Coastal Explorer.

To verify that the N2K messages were being received by the e125, I reviewed the attached log file in which I see 3 Class B Vessels that have transmitted the three Class B PGN's I would think would be sufficient to display the target. They are 129809 (Static B, Part A), 129810 (Static B, Part B) and 129039 (Class B Position). I have the entire log file, but it is 1.8 MB. The attached file is only the lines I believe are the messages for these PGN's & particular AIS targets.

For the three vessels, I believe the messages & times at which the messages appear in the log file are as follows: Since AIS messages are long, the complete message takes several lines in the log file and can be a few msecs from these time references below.

mmsi # 338006000
216.218 Part A
216.299 Part B
279.711 Position

mmsi # 338133193
252.516 Part A
254.383 Part B
343.208 Position

mmsi # 338151319
246.702 Part A
248.517 Part B
338.515 Position

These boats were transients in the same marina with my boat and continued to transmit their AIS data. Checking the ICOM 605 AIS list and Coastal Explorer over time showed the signal to be present, so it isn't a matter of signal loss. I also took photos of the e125 & Coastal Explorer displays showing the targets (or absence thereof). In a nearby harbor several Class A ships were present. I have photos showing how Coastal Explorer and the e125 both display the Class A targets correctly.

Hopefully this will provide some insight as to how to remedy my problem.

Thank you for the help.