New: Version 5.2.7 Click here for new features

AIS display on a Pocket PCHave you ever looked around, at sea, and been startled by the sight of a ship close by, and bearing down on you? Modern ships, especially passenger ferries, travel fast, and unless you keep a very vigilant lookout, they can appear out of nowhere!

AIS (Automatic Identification System) is a system of VHF transponders carried by commercial ships and by some smaller vessels. Each vessel broadcasts it's position, course and speed, and other useful information, which can be plotted on the digital chart. Together with your own GPS information, AIS can be used to alert you of a potential collision with a ship.

The purpose of PocketAIS is to provide the recreational boater with an additional tool to help keep clear of commercial shipping. With the audible collision alarm, the device will beep when your present course will pass too close to a ship.

The software can be downloaded here, and is a free add-on for existing Memory-Map Professional uses.


Remember that many vessels are not equipped with AIS transponders, and the hardware and software used to transmit, receive and plot the vessels may be prone to failure. Please exercise good seamanship, and keep a lookout at all times. To determine manually whether a vessel is on a collision course, take a series of bearings of it with a hand bearing compass. If the bearing is steady, you are on a collision course.

When you are navigating near large ships, remember that they may have very limited ability to maneuver. What seems like the wide open sea to you, may be a narrow, shallow, congested waterway to the ship. Never assume that you have right of way over a ship. If you are on a collision course, you should give way by making a large alteration of course, so your intentions are clear.

PocketAIS Features and Benefits

See ships plotted on the chart

Greater situation awareness

Audible collision alert   

You don't have to watch the screen all the time

Find the ship's name, radio callsign, size, type of ship, size, rate of turn, destination port and ETA

Aid in identifying a ship and predicting what they will do

Velocity vector shows ship's course and speed over ground on the chart

Visual aid to judge how ships will pass

Table showing all ships sorted by name, distance, bearing, closest point of approach, or time to closest point of approach

Find a specific ship fast in busy waters

Ships are color coded to show status and possible collision

Attention is drawn to ships that might be dangerous

Shows class A (commercial ships) and class B (voluntary) AIS transponders (if supported by the receiver hardware)

Shows all available vessels

Use a Windows Mobile device as an inexpensive, low-power, sunlight-viewable display at the helm (with waterproof case for outdoor mounting)

Affordable and practical on smaller craft

Works on a PC, as well as Windows Mobile

Use in the wheelhouse or nav station

Technical Details


You can run a simulated demo on your computer or PDA, without any additional hardware.

To receive and decode the AIS signals, you need an AIS receiver that outputs the AIVDM sentence on an NMEA or RS232 output. You also need a GPS to provide your own position, course and speed.

Some examples of compatible AIS receivers are:

We suggest you connect your GPS to the input of the receiver, or use a receiver with built-in GPS. This provides the GPS data (RMC sentences) combined with the AIS data on the output.

You can, alternatively, connect the AIS and GPS on separate serial ports (or using separate Serial-to-USB adaptors). You could also connect the AIS, GPS and other instruments via a multiplexor with AIS input capability (eg, MiniPlex-Lite). Note that you cannot use a regular NMEA multiplexor, because the AIS receiver typically outputs at 38400 baud, whereas other instruments use 4800 baud.

You can also consider using a bluetooth serial adaptor. This will allow you to use a PDA with a wireless connection anywhere on the boat.

Software Download

PocketAIS runs on Windows XP/2000, and on Microsoft Windows Mobile 2003 or later. You need a Memory-Map Professional license. If you already have a Memory-Map Navigator or Discoverer license, you can upgrade here. If you would like a free temporary evaluation, contact support@memory-map.com.

To get started you need to download two files: the latest version of Memory-Map Navigator, and the AIS add-on.

MMNav  Click here to Download


PocketAIS Version 5.2.7 Click here to Download  (1 MBytes)


First install Memory-Map Navigator. Install some charts, and set up your GPS. Enter your Professional license key, and click the Help/About menu to ensure that the Pro features are enabled. Then install the PocketAIS add-on.

If you are using a Windows Mobile device, run the AIS application on your desktop PC (Start / Programs / Memory-Map / AIS). In the AIS application, click PDA / Install PocketAIS, and follow the standard Windows Mobile installation prompts. From this point, use on the mobile device and PC are identical.


GPS and AIS on the same COM port

GPS and AIS on separate COM ports.

Demo Setup with no AIS receiver or GPS

AIS Target List

AIS target list showing Name, Distance, Bearing, Closest distance, and Time to closest approach

In the AIS application, you can view a list of all current targets, with their distance and bearing from your current position, and the distance and time of the closest point of approach.

You can sort the targets by clicking on the header of any column.

Clicking on a target shows you the full details in the area at the bottom of the window.

If the target is moving away from you, the CPA distance and time are blank.

AIS Targets on the Chart

The AIS targets are shown on the chart as animated icons. Each vessel is shown as a triangle, oriented according to its compass heading.

Each moving target has a velocity vector that shows its course and speed over the ground. All the velocity vectors are drawn on the same time scale, so you can judge the relative speed of different targets. You can determine, for example whether you will pass ahead or astern of a ship by looking at the heads of the velocity vectors.


How to use AIS velocity vectors in the chart view

For example, in the situation above, you will pass close ahead of the first ship, and well behind the second one.

The ship colors are as follows:

If you have the "Data" button enabled, tapping, or hovering with the mouse will show the pop-up data on the target.

If no data has been received from a target in 10 minutes, it is automatically deleted. If you want to keep a record of all targets, go to the Settings dialog in the AIS application, and enable the "Record tracks" option. This shows the tracklog of all ships and prevents them from being deleted. In a busy area, your chart will quickly become congested, and may cause the display to flicker. We suggest you delete unwanted tracks, or at least hide them, as they carry quite a high overhead.

Collision alarm

The software uses the course and speed of each target and your own course and speed to calculate your closest point of approach. If this is less than a given threshold, a warning is given. When you are on a collision course, the device will beep and the collision targets are shown in red.

Targets near the threshold are shown in yellow.

You can adjust the closest point of approach threshold, in terms of time and distance in the Settings menu. Targets that will pass closer than the specified distance, and within the specified time, are considered dangerous. These cause the beep and red target color. The time and distance thresholds are both doubled for the yellow warning targets.

Note that the size of the each ship (LOA) is added to the threshold, so you will still get some alarms if you set the distance to zero. If you want to disable the collision detection feature, set the time to zero instead, or just disable the beep.

If the alarm is beeping, there are three ways you can stop the alarm:


If you want to see, and record, the raw data coming from the AIS, proceed as follows.

If data is being received, you should see it scrolling up the window now

To record the data to a file, click Menu / Log file... and enter the name of a txt file the raw data should be written to. To stop data capture, click Menu / Log file and Cancel. The captured log file can be used as a simulation input to replay the data.

To see the decoded AIS messages:

Again, if data is being received, you should see it scrolling up the window now. You can capture a log file in the same way, but this data cannot be used as a simulation input.

When you have added these data "pages", you can toggle between them, and the original target list with the <<Page and Page>> buttons.

Version Changes

Version 5.2.7

Version 1.1



AIS is a very new technology in recreational boating, and we welcome any comments or questions you have about this software. Send them to support@memory-map.com