Where this data comes from

Where does the data come from?

Every entry is derived from AIS (Automatic Identification System) transmissions — the positional broadcasts large vessels make continuously for safety reasons, received via terrestrial receiver networks. We collect these signals around the clock, filter them to yachts of 30 m and over, and derive port calls from the positions. Nothing is scraped from other tracking sites and no private sources are used.

How are arrivals and departures decided?

Each harbour, anchorage and shipyard in the record has a hand-drawn boundary. A yacht whose positions sit inside a boundary continuously for at least twenty minutes is recorded as arrived; twenty sustained minutes outside closes the call and records a departure. The buffer prevents a vessel manoeuvring at a harbour mouth from producing a flurry of false entries.

Why are positions vague?

By design. Published coordinates are rounded to roughly 100 m — enough to say a yacht is in Port Hercule, deliberately not enough to say which berth. The map shows last recorded positions as periodic snapshots, refreshed with the record at most hourly; it is a record of where yachts have been, not a live surveillance feed.

Why is a yacht missing, or its history patchy?

Coverage is regional and grows over time: the record currently watches 21 harbours, anchorages and yards on the Côte d’Azur, around the Balearics and off Corsica and Sardinia. A yacht that sails beyond the monitored areas goes dark in the record until it returns — such gaps are shown honestly as time outside the monitored area rather than guessed at. Yachts also occasionally switch their AIS transmitters off.

What does “probable refit” mean?

A stay of more than seven days inside a shipyard’s boundary. It is an inference from time spent, not confirmed knowledge of work being done — hence “probable”.

What is the “economic footprint” figure?

An order-of-magnitude estimate of a yacht’s daily running spend — crew, berthing, fuel, maintenance and provisioning — computed as (length in metres ÷ 10)³ × €100. The cube is deliberate: running costs track a yacht’s volume rather than its length, so a 60 m yacht carries roughly eight times the daily spend of a 30 m one, not twice. The €100 constant was calibrated against real expense reports shared from several yachts, cross-checked against published references. A 2026 Deloitte study for the Superyacht Life Foundation and SYBAss reckons the global fleet averages around $10.5 million a year in economic contribution per yacht, with yachts over 60 m generating roughly 5.5 times the operational spending of smaller superyachts, and a Genova port study measured much the same curve in practice: €7,288 a day for yachts of 36–50 m and more than €46,000 a day above 75 m, where the formula gives €8,000 and €42,000. The result is rounded to two significant figures and is an indicative figure for the class of yacht, never an account of any particular yacht’s actual spending.

Sources: Trade Only Today on the Deloitte study · Forbes on the same study · Superyacht Life Foundation (Genova figures)

How fresh is the record?

Pages are rebuilt through the day as movements come in, typically within the hour. Every page carries an “as of” timestamp in the masthead stating exactly when its figures were generated.

Can I use the data?

The movements feed is published as RSS for personal use, and short excerpts with attribution are welcome. The record is compiled from safety broadcasts and is provided for general interest — it is not suitable for navigation or operational decisions.