JorgeinLondon
Well-Known Member
He's in the 8knot bit so strictly speaking sticking to the speed limit. Always seems like he isn't but maybe he is! Be interesting to see if he keeps it switched on past Teddington.
Messing about with online AIS website when I came accross this:
- Thread starter JorgeinLondon
- Start date
He's in the 8knot bit so strictly speaking sticking to the speed limit. Always seems like he isn't but maybe he is! Be interesting to see if he keeps it switched on past Teddington.
Actionmat
Well-Known Member
Have you got a link? I've never heard of that site before and I'd love to see what he's doing when he goes past me
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byron
RIP
WOW! I never thought of looking on the AIS website for vessels that far up the Thames. To a certain extent I am surprised Connaught is fitted with a transponder. For what reason I wonder, she's hardly a sea going vessel.
JorgeinLondon
Well-Known Member
It's a PLA requirement for passenger boats (and also if you want to go through London at 25 knots as opposed to 12).
The site is:
https://www.marinetraffic.com/en/ais/home/centerx:-0.3/centery:51.4/zoom:12
Looks like he turns it off once he goes through the lock at Teddington. Still interesting!
The site is:
https://www.marinetraffic.com/en/ais/home/centerx:-0.3/centery:51.4/zoom:12
Looks like he turns it off once he goes through the lock at Teddington. Still interesting!
Dave_Seager
Well-Known Member
You used to be able to track the Duck Tours amphibians travelling on the roads at much higher speeds than they ever managed afloat.
Actionmat
Well-Known Member
What a surprise! Perhaps the EA could be persuaded to make him leave it turned on? It's about bloody time something was done.
mlines
Well-Known Member
Is the Thames within radio range above Teddington, the system relies on people having Internet connected receivers being located nearby
And he is down at Kew (17:00hrs 4/9)
And he is down at Kew (17:00hrs 4/9)
byron
RIP
How does that work then? The system is world wide in the remotest spots. I thought it was SatNav based.
oldgit
Well-Known Member
JorgeinLondon
Well-Known Member
Maybe there has to be a radio link for the website to work...?
I thought it broadcast locally rather than constantly tracking via satellite.. Some of them plug into VHF radios but I assume that's so you can do a radio call to a ship directly via your AIS module.
I thought it broadcast locally rather than constantly tracking via satellite.. Some of them plug into VHF radios but I assume that's so you can do a radio call to a ship directly via your AIS module.
Bodach na mara
Well-Known Member
AFAIK the signal is generated by the vessel using info from its sat-nav and transmitted for the benefit of nearby craft if they have an AIS receiver. To show up on the marine traffic site, the signal must be received by a shore station and as has been said, maybe there is not one up the Thames. Ocean-going craft probably also transmit periodic updates via Sat-Com.
mlines
Well-Known Member
No its not.
AIS is VHF radio based and therefore has the range of a VHF radio only.
The receiver has a GPS in it which tells the receiver its position.
It then transmits this on short range VHF so all vessels with a suitable VHF AIS receiver get the position (and velocity/course etc.) information of nearby vessels.
Some members of the public have bought VHF AIS receivers and can therefore see ships within their neighbourhood, they then send this over the internet to websites such as this so the information can be collated. However it relies purely on the local coverage of the public receivers.
Commercial satellite AIS receivers are starting to appear. These are low earth orbit satellites that can pick up the same VHF signals as they pass over the ships. This gives some deep ocean coverage but the satellite constellation is not complete and the information is only downlinked once the satellite comes into range of the earth station.
oldgit
Well-Known Member
Alan ashore
Well-Known Member
My impression is that coverage on the river fades away to the West of central London, and most times if you try and follow a boat upriver it disappears well below Teddington. e.g. Cockney Sparrow just passed my window here. Last seen by Live Ship Maps 2 hours ago at Hurlingham. Just a question of where internet connected receivers are and variable range based on conditions - it may be there are some part-time receiving set-ups further west.
Chris_d
Well-Known Member
Any boat with an AIS enabled VHF receiver could still see Connaught upriver if its transmitting, you don't need the internet.