| It is a system which certain ships are required to carry. It consists of a GPS system and VHF transmitter and transmits their location and other information on the VHF Channels AIS 1 (161.975 Mhz) and AIS 2 (161.025 Mhz) |
| Well its was intended to help ships avoid colliding with each other by automatically transmitting their currrent positions and other data. It was also intended to assist ports with better information for their vessel traffic system. |
| It is collected by an SR162 AIS Receiver which is connected to a Shakespeare 5215 Antennna. The data is uploaded to the site via ftp from a host computer running shipplotter. The antenna is at about 30m elevation and is located in Piraeus. The cabling is 39m of RG213/U. The mapping technology used on the site is by google. The script is authored by
Ian McConnell. Data upload is via ws_ftp. The server is a linux VPS with 512mb ram and about 400mhz. |
| Yes as the system is based on VHF reception there are various reception problems. Suprisingly the AIS transmissions seem to go over mountains and buildings. There is also the matter of range as the system can collect data from about a 30-60 nautical mile range. There will be a few targets from further away but the data will probably be periodic or incomplete. It also depends on the power of the transmission from the ship.At the moment we have seen that there is poor reception at the eastern side of Eleusis bay which is most probably due to the mountain there. Definitely the system should not be relied on at all as providing complete data of all the vessels in the area. Some vessels may even switch off their transmitters when docked or at anchor. The reception on occasion may even be bad from some vessels and have corruption and therefore be discarded from the data set. |
| Yes as the AIS system on the ship may be a cheap one with an integral and poor GPS system. The system may otherwise be defective or misconfigured at time of viewing and transmitting incorrect information. Occasionally the system may even be ashore and being tested at a marine electronics company. There are various fields of information which are regularly entered by the crew such as whether the ship is sailing or docked/at anchor and also the destination port. The crew may have forgotten to update this information and it may therefore be showing the old and now incorrect data. |
| Due to the limitations of windows scheduler the data file is collected every 1 minute and then uploaded every two minutes. You can check towards the bottom of the chart page to see the timestamp of the new data and confirm it is updating. |
| The ships do not transmit all their data frequently, they transmit only their positional reports frequently which have their MMSI number (Maritime Mobile Service Identity) which is the number above. The GR is the flag of the ship, in this case Greek. Then at about every six minutes or so they transmit their full information. If we do not receive that full information report then the ship will not be identified by name, only the MMSI number. This is particularly a problem with far away ships where due to range problems we are only receiving a partial amount of their transmissions. |
| AIS Live has been providing data concerning the same locations as this site since 2004, albeit at a prohibitive subscription rate. Now it is available to the public at no cost. |
| Just reload the page manually. You probably loaded it at the same time as the data file was uploading. |
| This is normal. If something gets messed up then refresh the whole page. Its a pity that this happens with the google maps API. I am sorry about that. Recommended to close the page when you are not using it. |
| Just click continue and reload the page. |
| Maybe you have left the page open for a long time. Reload the page and check the time stamp towards the bottom of the page. If the timestamp is still old then there must be a technical problem with the data upload. Check back later. |
| I think firefox is better performance for this site, really it does handle the google maps API better. |
| This is related to ship type. The colours of each ship type are detailed on the chart page. |
F/B : Ferry Boat
LPG : Liquified Petroleum Gas Carrier
M/T : Motor Tanker
M/V : Motor Vessel
M/Y : Motor Yacht
RO/RO : Roll on / Roll Off Vessel (Carries Cars, Trucks, Could be RORO Ferry)
S/Y : Sailing Yacht |
| No. It is a personal research site. The data is provided without any warranty whatsoever. |
| United States |
| The following should be ignored as they are defective or testing AIS units : NAUTICAST,, TESTER VS. |
| In particular the popular NAUTICAST units can revert to default MMSI and other data following loss of power and complete discharge of the backup battery. More info here. |
| Although our base station is shown on the chart as Receiver it is not making any transmission whatsoever, neither does it have the capability to do so. The location is inserted instead in the computer data before it is uploaded. |
| If you want to help us show more areas then contact us. It would be nice to make this a community effort. |
| If you have a computer and ADSL connection then the cheapest way would be with the SR161 receiver (euro 233), Shakespeare 5215 (euro 50), Shipplotter Software (euro 30), SO-239 and BNC Connectors (euro 2). So 315 euro without the RG213/U cable which is say 2.5 euro per meter (but that is expensive cable for >10m runs). |
| Need also a power supply for 9-15v but that can be taken from any equipment that you are no longer using. Otherwise say 15-20 euro for one. Most importantly you need to have a high roof with no other buildings in the way or best, line of sight to the sea although that is not necessary. The computer and the ADSL would need to be on 24/7 though. |
| The data traffic on your ADSL might be about 30kb up and down per two minutes. Really it is nothing. It is not necessary to have a dedicated computer for this but the hardware requirements are not very big and it would be more convenient to do so. We are ready to receive shared date from any shipplotter user. |
