That probably means that not only are the charts out of date, but the software that runs the chartplotter is obsolete too. What's a boater to do?
Certainly one option is to go out and buy a new chartplotter. But that expense may not be necessary.
Our chartplotter is a Garmin 520 - very old indeed. And when I hooked up an AIS receiver to it, I began to get an inkling that something was not quite right. The main shortcoming that started this whole thing was that only Class B AIS targets were being displayed. At first I faulted the AIS receiver, but no, it was actually the fault of the chartplotter.
So I did a search on the Intertubes. And guess what? Garmin has a whole host of updates available online. For free! And as for our 520? We were at software version 3.00, and the current version for our device is 5.60. Reading thru the changelog shows that we were missing years of bug fixes, improvements, chart updates and a whole lot of functionality! Including proper handling of Class A AIS signals.
So I downloaded the update. But there's a catch.
As it turns out, the actual update is a file which you put on an SD card, and have that card in the chartplotter when you turn it on. The chartplotter finds the file, and then goes thru an update cycle. But thru remarkably provincial micro$oftian thinking, the downloaded file is a micro$oft executable. If you have a micro$oft computer, you can run this executable, which, yes you guessed it, just puts the file on an SD card. Why Garmin didn't simply provide the native file for download is a mystery that only micro$oft fanboys would understand (curse them and their ancestry forever).
It is not often that you can update your marine electronics for free... I am more than happy with our "new" chartplotter. I suspect you will be too!
nb: I previously reported that Garmin had discontinued software support for the old devices... NOT TRUE! It's still there, at the bottom of the page in the above link!