Yesterday Roger (a true DYI guy I’ve noted before) commented enthusiastically on Nasa Marine’s “AIS Radar.” It certainly does seem to provide a complete AIS listener for a very reasonable price, about $365, but I have some concerns. The main one is that Nasa “chose to simulate the plan position indicator (PPI) of a conventional radar display” (hence the name). In other words the target vessels are plotted relative to your own boat’s course and speed, not their true course and speed (though that’s shown in the data window). The goal is simplicity; a target on a collision course will generate a trail headed right at you. The problem is the plotting confusion possible when you change course or speed. Plus AIS Radar, like Nasa’s AIS Engine, only uses one frequency at a time—though that may not be an issue. And, finally, it does not support output to a PC. For more information, allGadgets has the manual posted here. Of course, my concerns may be unwarranted; I’d like to hear from users and/or try one myself.
In addition to Kees’ report yesterday, Dan sent in a link describing another successful test of the Nasa AIS engine, this time in conjunction with GPSNavX charting software for Mac computers. (Thanks, Dan, and I’ll follow up on your other Mac navigation suggestions soon). PC Maritime's interesting Navmaster Superyacht AIS package (look in the Leisure section) includes the same Nasa engine, which passed the company’s own testing and is reportedly pleasing early users. Superyacht’s AIS display looks like the best I’ve seen to date. Click here for the full screen shot and notice how the vessel is drawn to correct scale and its predicted track, i.e. rate of turn, is shown along with its heading. The user gets to control what data gets shown with the AIS target, plus the sidebar neatly categorizes all possible AIS info. I still want to know if there's a downside to only receiving one AIS channel at a time (I've asked Nasa), but it sure is exciting to see AIS hardware, and software, rapidly becoming affordable for even medium size yachts.
Update: “The same data is sent alternately on both channels so listening on one channel only is not much of a limitation. (It means the unit would 'hear' data every 6 seconds rather than 3 seconds from a vessel travelling at speed.)” — Nasa Marine
I’d never heard of this Nasa AIS “Engine” before, but oddly got two e-mails yesterday that referenced it. It seems almost too good to be true: a simple AIS listener that can feed ship information to a PC’s serial port for a mere $200 (plus cost of VHF antenna). It’s sold by a U.K. firm here, but does not seem to be listed at its manufacturer’s site here. One spec I see that might be a deal breaker is that a user must “Select 161.975 or 162.025 MHZ operation”. I thought AIS devices automatically use both. Please, someone, educate me on these mysteries!
Update: Be sure to read the comment from reader Kees who owns one of these listeners, reports good performance, and terms it an �outstanding no unbelievable value...� Thanks, Kees!
For a while now, a free registration at AISlive.com was possibly the best way to appreciate how valuable this anti-collision transponder technology actually is…short of, say, getting in trouble crossing the English Channel in zero visibility. AISlive has numerous coastal receivers listening for AIS messages, which it then charts on the Web in nearly real time. The screen shot below shows Amsterdam Harbor a few minutes ago. I’ve clicked on a boat called Unfurled and learned that it’s an 34m sailboat, one of the growing number AIS equipped yachts; Yme could probably stroll over and check it out! I can also go to the Straits of Dover, New York Harbor, and lots of other places and imagine how fabulous this information would be if I were cruising there right now (I wish).
But the IMO never contemplated Web broadcasting when it developed the AIS standard and some ships (and megayachts) apparently aren’t that pleased to see themselves so publicly tracked. There was talk of shutting AISlive down, but a much better resolution has been achieved. On May 3, what you see now on the site will become an expensive service limited to commercial and government subscribers. It’s an understandable change and the great news for us “private users/ship enthusiasts” is that “We have decided to create a public website (at our own cost) which is similar to the current AISLive but delayed by a minimum of one hour. We will not be charging for this service and hope you continue to enjoy the website.” Thank you, AISlive.com.
In addition to Kees’ report 
I’d never heard of this Nasa AIS “Engine” before, but oddly got two e-mails yesterday that referenced it. It seems almost too good to be true: a simple AIS listener that can feed ship information to a PC’s serial port for a mere $200 (plus cost of VHF antenna). It’s sold by a U.K. firm 