Standard Horizon GX2200 VHF Radio with AIS Receive

Next was the new marine VHF radio with AIS capability (Automatic Identification System). My radio is mounted on top of the instrument panel so making this change was very simple and took just a few minutes. Because it was the same brand as my existing radio all the connectors and plugs mated so the electrical hookup was also easy. AIS is a very interesting feature and if you are buying a new radio I would certainly consider it - especially if you cruise in places that have commercial traffic. The extra cost are reasonably small and the benefit large.  Plus no additional antenna is needed - the normal VHF antenna serves a dual purpose.

 If you are not familiar with AIS it is a radio signal that provides real time tracking system for boats. It is required in most all commercial vessels and many larger pleasure craft are also adding it.  It sends out a signal containing the boat’s name, location, heading, speed, distance away and more.  Think of it as being very similar to the system air traffic controllers use to monitor aircraft in a given area.

 A true duplex AIS system provides the ability to both transmit your information and receive the data from others. The range is usually 10 miles or better so a wide area is covered. But like all things marine it does come at a cost. Typical equipment currently runs from $600 to $1000. An alternative is a simplex receive only system. The downside is others can’t see you but it does offer you the ability to see them. One of the easiest ways to add the simplex function is to buy a conventional marine VHF radio with AIS. These can be purchased for less than $250 and as I am finding it works very well. 

 On the VHF radio there is a screen that can be selected to display the AIS information.  The screen (similar to a radar screen) is small but still gives the general idea of the nearby vessels location in relation to your boat. Using a control knob I can rotate through the displayed AIS transmitting boats within up to 10 miles (range is selectable) and select one. Once done the text information about the boat displays - including the boats name.

Why is this important to me? As you may know I have a good many river miles logged. On a regular basis during those trips I find the need to share the river with LARGE barge/tow traffic. Often I need to communicate with them to safely pass or overtake. The problem is calling them on the radio. There may be two or three tows in the general area so how do I hail the right one? Their name is usually on their transom but often very hard to read at a distance. The name is also usually on the side but by the time I can read it I am already overtaking so it does not help. And approaching from the front offers absolutely no clues at all. Normally I try to use what ends up being a cryptic combination of their location and description but it is far from optimal. AIS solves this problem.

 But it makes it even easier.  With the press of a couple buttons I can make a direct call to the other craft using the radio’s DSC (Digital Selective Calling). The radio in the other boat sounds an tone like a “ring” and they answer allowing two way communication. I don’t have to hail them or know their call name (although I do at that point).

 But it gets even better if the radio’s NMEA interface is connected the GPS/Chartplotter.  Now the AIS vessel is overlayed on the chartplotter's chart and selecting it's icon provides the vessels info on the plotter screen.  This is particularly useful when cruising rivers because a ship maybe located just a half mile away - right around the next bend - but not visible from the helm.  Also, on my plotter I can set alerts based on distance and or time and a alarm will sound if the vessel crosses them (more below).  After a season of use I will say I have always spotted the crafts approaching forward before the alarm sounded BUT several times faster AIS equipped pleasure craft have been advancing from the rear unnoticed and the alarm made me aware of the situation.

 Once on a narrow section of the Cumberland River I was warned on a boat coming up aft.  I looked at the data and it showed a 60' craft running 30 MPH. I thought there was obviously an error of some type - 60' and 30 MPH, now way!  I was wrong.  I watch the speed drop as it came off plane to pass me (which I greatly appreciated) and then bounce back up as he advanced the throttle. Yes, he was cruising at 30 MPH.

 If you are curious about AIS here is a free web site that requires no download to view AIS ships - - although the data is a little delayed.  There are also several app’s available for both Android and Apple devices. They display the same AIS information as the VHF radio and place the boat icons over maps or charts like the plotter. In fact, If you have both cell service and data to burn the app could be used in place of the marine hardware.  For my Android tablets and phones I like “FindShip” which is available for free and provides real time information. I actually use the paid ($3.99) version, FindShip Pro. The main additional feature it offers is the ability to show the “track” of any ship over the past 30 days. Not real useful but certainly interesting. The paid version also eliminates the ads but honestly they aren’t very obtrusive on the free app. And you don't have to be near the water for these to work. I often  fire up the app while sitting at home to see what is going on at Kentucky Lake 150 miles away.

 In conclusion, I must say I have been very impressed with the capabilities of AIS.  Dollar for dollar I think it is the best value of all the equipment purchased in the electronics upgrade.

Additional Info

Circles/Dots Are Shaoing AIS Targets

The top photo of the small screen on the radio itself with AIS targets showing.  The AIS range on this radio is up to 10 miles and in this situation is is set to display up to 2NM.  The dots indicate the location of the AIS boats relative to your location.  The small line radiating from the dot points to the boats heading.  The dots change from a circle to a black dot as you rotate through the list of available targets. 

Pressing the LIST  button brings up the screen above showing either the name or the MMSI number of the available targets.  In this case Golden H is selected and you can see its black dot location is about 1 NM to the starboard and slightly aft and heading away. Selecting the INFO button brings up another screen with more detailed information of the boats speed, heading, ect.  By selecting the CALL button I can start the quick process to make a direct radio call to Golden H.

With the radio networked I can bring up this screen on the plotter.  It list the names or the MMSi numbers of all the AIS vessels in the area.  In this situation there are eight so I have to scroll through the screen to see them all.  Although the radio is maxed at a 10 mile range the plotter will usually pickup anything with in 15 to 18 miles. On this screen I have selected the Stan Humphreys.  Touching it brings up the screen below.

Here is the INFO screen showing the AIS info on the Stan Humphreys. The amount of data for the individual boat will vary but this one is fairly complete. This is a loaded (draught 9.8) river tow making 4.9 MPH on a heading of 301. The Length and Beam are shown (this is just the tug - not the load of barges).  It is 7.75 miles away from me on a bearing of 264 degrees.  The system tells me it's status is SAFE meaning there is no collision course at the present time.   The CPA (Closest Point of Approach) shows if we both stay on our present course the closest we will come to one another is 6.96 miles in 38 minutes and 34 seconds (TCPA -  Time To Closest Point Of Arrivial)   I can set alarms for both CPA and TCPA and if it is calculated the boats will pass nearer than those limits the alarm be activated.  For example, I can say as long as any approaching AIS vessels are more than a mile away or more than 3 minutes away thats OK but if it is calculated to pass closer let me know.  This is a great safety feature.

At the bottom there is a "CALL" button which will start the direct radio call and the "SHOW" button which brings up the screen below.

Above is how the icon of a vessel shows on the chart screen.  It places it right on the chart so I have a very good idea of it's location.  The line again shows its direction of travel.  If it is dead in the water only the triangle will show - no line. 

If I am just cruising and notice the triangle symbol on the chart, all I have to do is touch the triangle.  A text box will appear showing the boats name or MMSI #.  Touching the text box then brings up the INFO screen shown several photos above. It is just a quicker way to get to the boat's AIS data. 

NOTE - Class A AIS transmits the craft's MMSI number and other critical location information every 2 to 10 seconds BUT the other data like the vessel's name, draught and size are only broadcast every 6 minutes.  So  you may have to wait a little to get all the available info.  (see full list below)

List of data transmitted by AIS  


An AIS transceiver sends the following data every 2 to 10 seconds depending on a vessel's speed while underway, and every 3 minutes while a vessel is at anchor:

  • The vessel's Maritime Mobile Service Identity (MMSI) – a unique nine digit identification number.
  • Navigation status – "at anchor", "under way using engine(s)", "not under command", etc.
  • Rate of turn – right or left, from 0 to 720 degrees per minute
  • Speed over ground – 0.1-knot (0.19 km/h) resolution from 0 to 102 knots (189 km/h)
  • Positional accuracy:
    • Longitude – to 0.0001 minutes
    • Latitude – to 0.0001 minutes
  • Course over ground – relative to true north to 0.1°
  • True heading – 0 to 359 degrees (for example from a gyro compass)
  • True bearing at own position. 0 to 359 degrees
  • UTC Seconds – The seconds field of the UTC time when these data were generated. A complete timestamp is not present.

In addition, the following data are broadcast every 6 minutes:

  • IMO ship identification number – a seven digit number that remains unchanged upon transfer of the ship's registration to another country
  • Radio call sign – international radio call sign, up to seven characters, assigned to the vessel by its country of registry
  • Name – 20 characters to represent the name of the vessel
  • Type of ship/cargo
  • Dimensions of ship – to nearest meter
  • Location of positioning system's (e.g., GPS) antenna on board the vessel - in meters aft of bow and meters port or starboard
  • Type of positioning system – such as GPS, DGPS or LORAN-C.
  • Draught of ship – 0.1 meter to 25.5 meters
  • Destination – max. 20 characters
  • ETA (estimated time of arrival) at destination – UTC month/date hour:minute
  • optional : high precision time request, a vessel can request other vessels provide a high precision UTC time and datestamp