Sunday, August 6, 2017

AIS & Internet Position Reports

A relatively recent addition to maritime electronics are Automatic Identification Systems (AIS.) These are ship mounted transponders that both broadcast the ships location, COG and SOG and report the same data from ships in the vicinity. Since they operate on the marine VHF bands their reach is about 25 nautical miles for big ships, 10 to 15 nautical miles for pleasure craft.* They are a real plus for sailboats as we are almost invisible on radar. Under the COLREGS sailboats have almost unlimited privilege. The powered vessels have to stay out of our way. In the old days ships frequently had to be in visual range to see a sailboat. This resulted in lots of close calls. Now they know we are here way out. It is fun to watch them tweek their heading a degree or two to give us a one nautical mile closest point of approach. One nautical mile seems to be the courtesy distance. They are a real safety boost.

But, as usual, I digress.

An unanticipated benefit of AIS is that it can be a passive way for friends and family to keep track of your location. Several companies have taken the strategy introduced (I think) by Wunderground for weather. They are seeding the world with shore mounted AIS receivers attached to the Internet as Wunderground did with weather receivers. Sail into the vicinity of one of these receivers and the boat's location is reported. Very nice.

The problems unfortunately are two. There are no receivers in the open ocean**. If you sail like I do you can disappear for days. And if you visit fun places like South Buru, Indonesia there are no AIS receivers either. Fortunately there is a way to overcome this limitation - at least with the provider Marine Traffic ( you can email position reports keeping your friends, enemies, and creditors up to date.

I am participating in the Wonderful Sail 2 Indonesia rally. There are about sixty boats. On a whim I upgraded in Marine Traffic so I could keep track of all sixty. (I think 5 are free.) The results were enlightening. Of all the boats in the rally only Reboot shows in South Buru. The other twenty I can see visually and on my multifunction display are somewhere else. Reboot is only here because I filed an email position report as there is no AIS receiver here. The rest are spread out from Horn/Thursday Island Australia to wherever they happened to pass a receiver (e.g. Some but not all the boats triggered the receiver in the Banda Island group.) So perhaps not so useful for keeping friends informed unless you fill in the reception blanks.*** But fun none the less.

Fair winds and following seas :)

* Due to power and antenna height differences.

** AIS reception by satellite works with limitations. To my knowledge no one provides AIS satellite tracking on the Internet for free. Also, I think some cruise ships echo the received data from their AIS to the Internet. Reboot's position has popped up from time to time when passed by a cruise ship in the Caribbean.

*** If you sail in highly populated areas like the United States you will get an almost continuous track.

Posted at anchor, South Buru Indonesia

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