The Comnav Mariner AIS that I installed a few weeks ago turned out to be defective. After installing, I checked my transmission history, and found that I was only transmitting about once a day if lucky. I brought this up to Comnav support, and initially, they insisted that I had misconfigured the settings. I exchanged setting and screen captures with them, and they finally agreed that the unit appeared to be defective in the transmission area. When I brought this up to my local vendor, he too doubted that it was the unit, and said that most likely, I had misconfigured the unit. He said that they had sold dozens of these units, and never had a problem. I stuck to my guns and sent the unit back to Comnav. After a few weeks and some prodding, I got a new unit and reinstalled. I'm happy to say that the new unit is behaving normally, transmitting every 15-20 minutes, and verifiable through http://www.marinetraffic.com/.
I wonder how many fishermen or sailors install the unit, test once and walk alway, thinking that this important collision avoidance system is working as designed. It's important to check that the technology is working as advertised.