AIS year in review 2024
Stats and interesting ships I saw come sailing in
Hello! I live in Kinghorn, Fife, overlooking the island of Inchkeith and the shipping channel of the Firth of Forth. This is the gateway to Edinburgh, with major dockyards, terminals and ports serving the maritime communities and industries along the coast.
With a front row seat to marine activity in the Forth, and as a fan of visualising data about the physical world, I decided I had to install an AIS receiver on my roof.
AIS is the generically named "automatic identification system", a standardised protocol transmitted over VHF that tracks vessel movements worldwide. It's how websites like MarineTraffic work.
I've been collecting data since 2023 and have wanted to visually tell some of the stories hidden in it for a while. An end of year review feels like an appropriate juncture, so here we are.
All photos taken by me (often through binoculars) and a security camera also mounted on the roof that captures the view every 15 seconds.
Enough waffle…
2024 Stats
Total positions received: 44,039,066
Total unique vessels seen: 2,410
Total vessels seen for the first time: 1,477
Tropospheric propagation
This map shows an average day in August. 60 unique vessels with the furthest ship 78km out in the North Sea.
VHF radio waves are normally restricted by line of sight, which puts their range at around 100km or so.
Normally, the receiver detects around 300-400 ships in a given month, but in September 2024 that shot up to just shy of 1,000, around 400 of which we'd never seen before. What happened?
Under the right weather conditions, a phenomenon called tropospheric propagation can occur. In short, a layer of warm air higher up in the atmosphere with cooler air below (an inversion) causes radio waves to refract, redirecting them back towards the Earth instead of shooting off into space.
This particularly affects shorter wavelength radio waves like VHF, and allows signals to be carried much further distances on waves repeatedly bouncing along this atmospheric "duct".
When this happens, an AIS receiver's range can increase dramatically.
Long range AIS
This was our detection range on September 18th 2024.
We picked up 566 unique vessels — most of the traffic in the North Sea, and the furthest ship was 840km away off the coast of Denmark.
This was probably the result of a lingering area of particularly high pressure over the sea, with clear skies and minimal wind. This likely led to a temperature inversion and the perfect conditions for tropospheric ducting.
Full timelapse on YouTube
Most frequent destinations
Along with their positions and vital statistics, vessels use AIS to report their destinations. This is manually typed in by the crew and is often unreliable, but after some cleanup we can work out where most ships are heading. These were the top 10 destinations reported by vessels passing between Kinghorn and Inchkeith.
Click through the list to zoom in on a destination.
Most reported vessels
These were the most seen vessels passing between Kinghorn and Inchkeith in 2024, counted at most once per hour.
Mostly local craft that help keep traffic in the Forth running smoothly and safely on a daily basis… oh and one container ship who's just happy to be here.
The map shows their median position for the year.
Longest vessels
These were the longest ships that passed between Kinghorn and Inchkeith in 2024.
Lots of oil tankers, but we also had a couple of visits from the Cunard line. In September, Queen Mary 2, the only remaining transatlantic ocean liner, sailed up the Forth. We also glimpsed Queen Anne through the fog, not long after her maiden voyage in May.
Click on any ship for a short timelapse of their closest pass.
Fastest vessels
These were the fastest vessels that passed between Kinghorn and Inchkeith in 2024. No webcam photos, they're all too small.
Press the start button to hold a (fictional, sped up) race over 5km.
The winner is Kinghorn's own RNLI lifeboat B-836 Tommy Niven. Let's take a closer look…
(20x)
Kinghorn RNLI
These are the 65 times the Kinghorn lifeboat was picked up moving more than 10kts off Kinghorn beach. It's not a complete list but captures a flavour of the life-saving shouts and exercises carried out over the year.
Click on any thumbnail below or path on the map to (usually) see a timelapse of a lifeboat launch or recovery.
Look out for the Loony Dook on January 1st and a festive surprise on the map on December 15th
Busiest day
The day with the most vessels passing between Kinghorn and Inchkeith was Saturday 11th May.
Following a stunning aurora the night before, it was a still and sunny summer day. This perhaps lured out a number of pleasure craft and sailing boats, along with the usual array of tankers, cargo ships, cruise liners and support boats.
118 different vessels in total were picked up over the course of the day. The 23 shown here are those that passed between Kinghorn and Inchkeith.
Timelapse video on YouTube (with aurora)
HMS Queen Elizabeth
On the morning of Thu 21st March, the Royal Navy's flagship aircraft carrier, HMS Queen Elizabeth (R08) entered the Forth. She was headed to Rosyth dockyard for unscheduled repairs to her shaft lines.
On Mon 22nd July, she passed back under the Forth bridges and returned to Portsmouth.
Valaris 247
In the early hours of Wed 10th April, jackup drilling rig Valaris 247 was towed past Kinghorn to rendez-vous with Xin Yao Hua, a heavy load carrier preparing to deliver it around the world to Australia.
Accompanied by a fleet of local tugboats, the anchor handling tug supply vessel (AHTS), Brage Viking led the operation with a pilot delivered from Granton by Forth Leopard.
Valaris 247
Valaris 247 was floated onto a semi-submerged Xin Yao Hua, and remained at anchor until Thu 18th April, when it left the Forth to begin its voyage south, arriving in Darwin, Australia on Sun 30th June.
RRS Sir David Attenborough
And on the theme of long journeys…
On Wed 26th June, hidden by the haar, the British Antarctic Survey's research vessel RRS Sir David Attenborough (AKA Boaty McBoatface) sailed past Inchkeith en route to Rosyth dockyard for routine maintenance.
Boaty would pass by 3 more times in 2024, bookending a trip to Iceland, before setting off on the return journey to the Antarctic Peninsula on Mon 30th September.
The End
I hope you enjoyed this tour of vessel activity in the Forth.
If you're looking for someone to do this sort of thing (data programming and design, javascript, or any full stack web stuff) I'm available for work, get in touch:
[email protected] • bluesky • mastodon
See you next year!
