I've been wondering what happened to the Coast Guard's plan to require AIS on lots more commercial vessels plying U.S. waters, first discussed here in December '08.  Unfortunately the legalese around federal rulemaking means that the normally very informative Jorge Arroyo -- project manager in the CG's Office of Navigation Systems -- can only say that the comments collected in early 2009 are being analyzed.  I hope the Final Rule comes out soon, because looking at that slide above I see that compliance after the rule will take about half a year and, man-o-man, I'd like see those particular 17,442 vessels transmitting AIS ASAP...

For instance, among those 5,520 fishing vessels over 64' are a bunch that have caused me a fair bit of night watch anxiety; when they're at work out on the Gulf of Maine they're usually burning wicked bright deck lights (that must obscure their vision) and going every which way, sometimes in widespread gangs.  (AIS could also help protect those guys from greater dangers than yacht jockeys like me.)  And among the 2,167 passenger vessels over 64' are lots of Maine State Ferries that are often the biggest, scariest moving object encountered during a foggy day cruise.  AIS on all those boats is going to be very good thing, and I'll bet that many of you can visualize similar examples off that list.  Which came, incidentally, from a presentation that Arroyo gave to various key groups, and which you can find in full here.
   That's also where I found the table below, which shows how many feet a vessel will move between AIS transmissions, depending on its speed and which type of AIS it's carrying.  I've been nattering about this situation for years, but these numbers cast it in a new way.  A Class A vessel going 30 knots transmits every 2 seconds, or 100 feet, while a Class B is still transmitting at 30 seconds, which equals 1,500 feet, which equals a quarter mile, which equals close-in plotting that's pretty darn "jumpy".  (And never mind the inexpensive "multiplexing" AIS receivers that flip flop from one channel to other, and thus will probably only see that fast Class B once per half mile; if you own one, consider an uprade.)  As discussed in that original entry, and in Arroyo's presentations, the USCG went into this rulemaking process unsure which commercial vessels would be allowed to carry Class B and which might be made to install Class A.  I'm wondering if what seems like a long period of "comment analysis" (it may not be long in government terms) may be partially about waiting for less expensive Class A transponders to come to market.   Like the ComNav Voyager X3, which hopefully is just the first of many. Whatever, I, for one, would like to see this deal get done.