Vessel watch · Stockholm archipelago
ISeaYou watches live AIS traffic around Trälhavet. Mark out a stretch of water, and the moment a vessel enters it you are told its name, what it is doing and — where a photograph exists — what it looks like.
Web · iPhone · Apple Watch
How it works
Every rule runs on our server, against a single live feed — so a zone stays armed while every app is closed.
Step 1
Trace a shape on the chart: a channel mouth, the sound in front of your jetty, the stretch of bay you can see from the kitchen window. Draw as many as you like.
Step 2
Each position report is checked against every zone as it arrives. A vessel is announced on its very first fix inside — we don't wait for a second one, because on this feed the second one can be half an hour away.
Step 3
Name, type, speed, course, size and reported destination — and a photograph, with its credit, when one is on record. Where there isn't one, a drawn silhouette says so plainly.
The dossier
AIS tells you less than you'd think. A transponder broadcasts who a vessel is, how big she is and where she's heading — and nothing about who runs her, when she was built, or what she looks like.
ISeaYou fills the gaps from open sources, in order, and stops when it runs out:
It never guesses. A value we don't have is shown as missing, not estimated. Photographs carry their credit and licence, because Commons images are licensed, not free-floating.
Nordvik
Passenger · 1962
Example card. Passenger count isn't in AIS, so it stays blank until a source has it.
Measured, not assumed
Before deciding how alerts should work, we recorded an hour of traffic on Trälhavet and measured it.
A ship's transponder broadcasts every few seconds, but the free public feed we rely on thins that out to about once a minute — and sometimes goes quiet for half an hour. Waiting for a second report to "confirm" an entry would mean hearing about a ferry after it had already passed.
So ISeaYou alerts on the first report inside a zone, and saves its caution for the other end: a vessel is only considered gone after half an hour of silence, and the same vessel won't set off the same zone twice within 30 minutes.
Honest limits
ISeaYou shows what the water broadcasts, and says so when something isn't there.
| Carried by AIS | Not carried by AIS |
|---|---|
| Name, MMSI, IMO, call sign | Passenger count |
| Ship type, length and beam, draught | Photograph, build year, operator |
| Position, speed, course, heading, status | Tonnage |
| Destination and ETA, as typed by the crew | Anything the crew didn't type |
Access
ISeaYou is an experiment by Trälhavet Technologies, running on our own server and a shared live feed. Accounts are invite-only for now. Tell us where you watch from, and we'll send you a code.
