How are we tracking Gavan and the rest of the fleet taking part in the Talisker Whisky Atlantic Challenge?
The Yellow Brick tracking you see on the Talisker Challenge broadcasts every 4 hours. However the rowing boats also car the Automatic Identification System (AIS) transponder system which broadcasts every couple of minutes. It is quite a simple system as it shares the VHF radio on the boat and often its aerial. Other ships pick up this signal and the information contained within. This includes boat name, the unique MMSI identifier number, boat length speed and direction. Ships transmit even more information such as where they are going and what port they last visited. This system has been a huge addition to safety of life at sea but it is also great for just snooping around the world.
In addition to ships picking up each others information once they are within broadcast distance of a shore base station e.g. Galway Coastguard Radio mast on Tonabrocky the signal can be further transmitted over the internet. This allows you to track ships around the coastline anywhere around the world. The odd time you see a target going at 120knots, this is typically a coastguard rescue helicopter who carry marine as well as aircraft transponders.
If you zoom into busy shipping lanes such as the English Channel, near Rotterdam, Shanghai, LA, etc the number of ships will surprise you.
In recent years satellites have begun picking up the VHF signals from mid ocean AIS units. The satellites have an unimpeded view a few miles above the ship. On some sites you can see the ships offshore but cannot identify them without paying for a subscription. The most popular sites are www.marinetraffic.comwww.vesselfinder.com and www.shipfinder.com. If you google AIS trackers you will find them.
The Talisker Rowers can be seen on the AIS now but its hard to identify them and you get no details. However once they get within reach of the shore you can fully identify the boats and get full information. The rule of thumb for VHF is 'metres high miles wide’ ,so a 10 meter high aerial will reach 10 nautical miles. Weather dictates a lot and often the range is further. Unfortunately the rowing boats aerials are only about 2 metres high. The height of the Antiguan Coast guard Radio Masts will determine a lot but Technically this “may" allow us to follow the last 10 or so miles of the race minute by minute.Given how close it is now there will be plenty of us doing so.
You can input the name of a vessel and search for it. The most recent search for Doireann on shipfinder shows her south of La Gomera Canary islands on 14 Dec, its last satellite position was seven hours ago. vesselfinder was 16/12 off the Canaries while Marine traffic spotted her on satellite 10 minutes ago.
Here is a screen grab of a "familiar pair of pleasure craft" targets heading towards Antigua: I'm sure they would argue about the ‘pleasure’ denotion but Rowing has not been designated a colour - yet.