Wednesday, 6 August 2014

Tracking the OGA Fleet (by Trevor)

Those of us cooped up ashore in our homes and offices have had great fun following some of the fleet with the mAIS system.  This was originally designed for large ships to transmit short range ‘pings’ of their position, speed and heading.  Any ship within radio range could pick up these short messages and then work out whether a collision was going to happen — and take avoiding action if necessary.  The same equipment transmits & receives and is compulsory on all registered merchant ships.

Many yachts, including Bonita, have an AIS receiver incorporated within a chart plotter so the positions of nearby merchant ships can be seen; however she does not have the additional AIS transponder to transmit her position.


Some clever techie noted that if AIS messages can be received at a shore-based radio station, the same information could be used to display ship positions live on the Internet.  There are several organisations that do this, but we find MarineTraffic to be the  most reliable http://www.marinetraffic.com/ais/ 

Bonita from Haarlem to Amsterdam
Drag the map around with your cursor and zoom with the navigation bar that appears on the right hand side when you move the cursor.   Now zoom in on the English Channel or drag the map across to Shanghai.  See the live position of every ship in the area. Then right click on one of the ships. It will display the ship (or yacht's) details as well as options to see their track, itinerary, nearby vessels etc.  You can even add waypoints and calculate arrival times.  On the left hand side are useful filters to add satellite views, filter out certain types of vessel, and even build your own 'fleet'.

If you search for Bonita‑Yawl you'll see her position if she’s transmitting.  If she hasn't done so for 24 hours, it will say ‘Out of Range’.  It will also tell you the last time she transmitted. The picture above shows her journey a few days ago from Haarlem to Amsterdam.

You can also download MarineTraffic for an Android phone, iPhone or tablet from here.  If you really want a great view on your PC or tablet, get the Google Earth 3D extension from here
Android Screen

Not only can a smart phone be used to receive AIS data it can also be used to transmit it and this is how Bonita's AIS transmissions are made. As long as she’s within range of a cellular network (which is when she is in coastal waters), the phone will send out her speed, position and heading every few minutes.  The messages are tiny, so the cost is negligible with a UK data plan. If she goes out of cellular range for a time, the app stores up a couple of hours worth of positions and then sends them when connected.

Transmitting AIS data makes a vessel much more visible to merchant ships which is of particular value at night or in poor visibility. So how does one set up a smart phone to transmit AIS data?




Please drop me an email if you have any technical difficulties - trevor.wilkins@gmail.com - Bonita's IT admin.
Busy English Channel