AIS – Not Just for Big Boats Any More

We all know that keeping watch for other vessels and “objects” in the water is one of the basic requirements of good seamanship, whether you’re out on the lake, bay, coastal cruising or making a trans-Atlantic passage.  It’s my 2nd Rule of Sailing, “Don’t hit anything!” (1st Rule: Keep everyone on the boat!). For centuries a “weather eye” was our only source of collision avoidance information. Then came RADAR if you happened to have it. But with the advent and evolution of AIS, Automatic Identification System), we all, from the biggest to smallest boat, now have much better capabilities available to proactively see and respond to potential collision threats – and find people in the water.

Check this out…there are a LOT of boats out there! https://www.marinetraffic.com/en/ais/home/centerx:-96.5/centery:32.1/zoom:4

Big boat collision avoidance is where AIS has its roots. AIS was developed in the 1990s and Class A AIS Transceivers became a requirement for vessels over 300GT back in 2002.  Continued evolution by the AIS technical standard committee has produced AIS standards and product versions to fit all types of vessels, right down to your centerboard dinghy or fishing boat, and more recently all the way down to your own personal pocket flashlight size AIS transmitter.

So what is AIS? AIS per USCG rules is: “a maritime navigation safety communications system standardized by the International Telecommunication Union (), adopted by the International Maritime Organization (), that–

(1) Provides vessel information, including the vessel’s identity, type, position, course, speed, navigational status and other safety-related information automatically to appropriately equipped shore stations, other ships, and aircraft;

(2) Receives automatically such information from similarly fitted ships, monitors and tracks ships; and

(3) Exchanges data with shore-based facilities.

transmitters are not required on all vessels, but AIS transceivers have become a very popular method for pleasure boaters to improve their safety, even if only in “Receive Only Mode”.  With an AIS receiver aboard your boat you are able to see other boats AIS transmissions – IF THEY ARE TRANSMITTING AIS – telling you their boat name and type, position, course and speed.  When processed by your navigation software it’s like watching a video game rather than watching and tracking RADAR “blobs” – if you have RADAR – or standing out on the bow scanning the horizon for potential threats.  On your chart plotter AIS give you a visual location of other boats and the AIS software can compare your position, course and speed with that of other vessels and estimate your CPA (Closest Point of Approach) and your TCPA (the Time till your CPA). CPA and TCPA can help you to take evasive action before you even see that 900’ freighter doing 18kts toward you. (More about CPA, TCPA and Collision Avoidance in future posts.)

Taking AIS tracking ability even further, there are now Personal AIS beacons (Check them out here)  that allow AIS Receivers to electronically track the location of a Person In the Water on your chart plotter. So in addition to maintaining visual contact and “dropping an MOB WAYPOINT” on your chartplotter the personal AIS allows you to “see” where the PIW is on your chart plotter and help you navigate to them even if they are moving with current and waves.

Helping us keep watch to avoid collisions – we still need to keep watch as NOT EVERYONE HAS AIS! – and quickly recovering anyone that goes overboard are critical capabilities for boating safety.  Using AIS systems on your boat, and transmitters on your PFD, can help improve your success at both.