PRODUCT REVIEW : NASA AIS Engine 2

AIS receiver for use with a Computer or Chart Plotter

Having spent several very trying hours in fog the last time I crossed the approach to the shipping lanes off Finisterre, coaxing my brain to plot several simultaneous radar targets onto a manoeuvring board to work out the attitude and risk of collision, I vowed to have AIS to help me before my next encounter with this nautical version of space invaders.

AIS means ‘Automatic Identification System' and is a mechanism allowing vessels to broadcast their position, course, speed and identity to other vessels to complement their radar echoes. AIS is in no respect a substitute for radar - only vessels mandated by SOLAS chapter 5 have to fit AIS, so there are plenty of vessels out there which don't have to use it and other hard things which will damage your boat if you don't use radar to avoid them. What AIS does do, though, is let you know almost instantaneously what each radar target is doing, so you can then concentrate on using plots or ARPA (Automatic Radar Plotting Aid) to get the same information out of the radar targets not fitted with AIS.

There are two flavours of AIS, types A and B. Type A is the compulsory big ship system, and requires a high degree of integration with the ship's systems to generate the information it broadcasts - for example, rudder angle and rate of turn are required pieces of additional information. Type B is the voluntary fit of either a receiver or a transceiver (which transmits as well as receives), and is much less integrated with the boat's systems. Both types transmit their information as a radio signal in a digital format, using VHF on frequencies in the same bands as are used for marine voice communication. The range is therefor much the same - basically the visible horizon.

The interval between transmissions varies according to what the vessel is doing at the time: A rapidly moving craft will update its position, course and speed perhaps every 7 seconds, whilst a moored craft may only issue an update once every 6 minutes or so. Broadcasts from type A installations always have priority over broadcasts from type B, so if you are in a very crowded waterway you may see the updates from type B craft slow down whilst the updates from type A will continue at the same rapidity. None of this detracts in any way from the effectiveness of AIS - it just means that the system has been very well thought out and the potential for conflict from many AIS broadcasters carefully thought through.

I intend eventually to fit a Type B transceiver so that other vessels can be made aware, through AIS, of what I am doing, as well as me being aware of what they are up to. However first I wanted to gain experience by fitting the cheapest AIS receiver I could find ... which led me to NASA Marine Ltd's AIS Engine.

This device is a ‘black box' (actually it is white, but the industry has always called a box which has no knobs and only does something if connected it to a computer a ‘black box', so there you go). It can only function if connected to a computer running appropriate software, or to a chart plotter equipped to communicate with such a device. The receiver cost me just under £100 - very much less than its competitors, and less than half the cost of the NASA AIS receiver which incorporates its own display. Inside the package was the device itself a data cable for connecting to the computer's serial port, a power cable, a single sheet of paper with details of how the AIS Engine 2 differed from its predecessor, and a CD containing software and what NASA apparently thinks is an instruction manual. This did not even tell me which was positive and which negative for the power cable, and when I tackled the manufacturer about what is, frankly, the worst set of instructions for an electronic system I have ever seen, they told me that the single sheet of paper should have had connection details on the back.

Since I needed software to get anything out of the unit at all, I started by investigating the software on the supplied CD. This, incidentally, was labelled Software On Board, and made no mention of NASA or AIS whatsoever - not a propitious start. The disk had two applications on it - Software On Board and SeaClear. I started with the former, to be faced by an out-of-date message suggesting I wound back the clock on my computer to get the software to run. I declined and went on to SeaClear. SeaClear did install, it did have a manual, and seemed to be a charting programme of the type that requires a very laborious importation of charts as images which then have to be calibrated manually before use. No doubt SeaClear does communicate with an AIS receiver, but there was only one brief mention about it in the manual and no mention of NASA at all. Then I looked at the NASA manual on the CD, which basically was a specification for serial communications from the AIS Engine to the computer and vice-versa. At this point I might easily have given up, but instead I searched the internet and found a software application called ShipPlotter which, for me, transformed the situation.

ShipPlotter is mainly targeted at radio amateurs who are interested in AIS and want to display ships in their area. As such it has many facilities which skippers will not want or need, such as the ability to interface directly with a radio receiver and decode signals without the need for an AIS Engine at all. However it also has all the facilities that you could want for using the AIS Engine at sea. It also has an excellent manual - you will have gathered by now that I am a great fan of manuals!

Not only did ShipPlotter cost me nothing to download and try out, but it also has a sufficient following to have user groups set up. Within the hour I had advice from these groups as to how to connect the AIS Engine to ShipPlotter and, connecting it to my masthead VHF antenna, was receiving AIS messages from up to 30 miles away.

My ShipPlotter display, connected to the NASA AIS Engine in a ‘North Up', ‘My Vessel Centred', ‘Radar-Ring' display includes coastline which is a satellite view I downloaded in order to give an appreciation of position. (ShipPlotter has a facility to do this and calibrates the images for you). I've not yet tried to interface this to my computer-based chart software, as I've found this view and its compatibility with my radar display to be of greatest utility. The AIS targets are displayed with their names, past track and future projected track. When a target is selected an information panel is displayed with additional information, including their MMSI number in case it is necessary to call them on DSC VHF. A guard ring can be defined around ‘My Vessel', which generates automatic warnings of any projected vessel path crossing into the ring. In addition, a route can be defined for ‘My Vessel', and conflicts of projected tracks at the time ‘My Vessel' will be at any given position along the programmed route can be reported. In addition to the fact that this very nice piece of software did everything I wanted and only cost me €15 to register, it also provided full and complete facilities for connecting a serial communicating instrument such as the NASA AIS Engine, including the ability to suspend and start communications from within the application. This is important, as anybody who has turned on a computer with a charting programme and found that the GPS has suddenly been recognised as a computer mouse will attest!

So, finally, with the help of an excellent piece of free software, I managed to get the AIS Engine up and running, since when it has met all my requirements. There is a facility for connecting your own boat's GPS to the AIS Engine so that it can be relayed on to the software, but as ShipPlotter allows you to configure as many input data streams as you like I just leave the GPS connected in the same way as I do for my chart plotting software - ShipPlotter manages to find it and use it to centre the display. I can then keep both that application and my chart plotter open at the same time and swap between them.

I have only used the AIS engine in its default mode as, in order to change from the default serial communication, instructions have to be sent from the computer to the engine. I have yet to find out how to do this as the ‘manual' is, needless to say, silent on the question.

In conclusion, I am delighted with the performance of NASA's AIS Engine and just glad that I persevered beyond their dreadful set of instructions.

The NASA dual frequency AIS receiver Engine 2 is available from all major marine electronics distributors. NASA Marine Instruments were contacted for missing instructions during the writing of this review but despite repeated requests did not provide them.

ShipPlotter software can be downloaded at www.coaa.co.uk/shipplotter. One of the user groups mentioned in the text will be found at groups.yahoo.com/group/shipplotter/.