Direct answer
Why do live oil tanker AIS maps undercount traffic? Automatic Identification System (AIS) is a self-reported collision-avoidance broadcast, not a customs or military census. A public map can only plot messages that arrive. Ships may sail with transponders off or intermittent — “dark” AIS — coverage can thin away from coastal receivers even when satellite AIS helps, voyage fields are crew-entered, and analytics desks often revise earlier prints when a dark leg is confirmed later and backdated. OilRoutes is a visualization layer over AISStream.io filtered to oil-tanker AIS types 80–89 and optional military type 35. A silent crossing can still be a real crossing; it will not appear as a confident count on the live map.
A glowing pin is a radio object that spoke — not a barrel, not a customs stamp, and not proof the rest of the ocean is empty. Field literacy stays on how to read live AIS. Dated 2026 Hormuz caveats stay on the Hormuz tanker-traffic note. This page will not re-scrape them.
Open the live map and fly to Hormuz →
AIS is a broadcast, not a ledger
AIS is a VHF safety system. Ships send identity and position so nearby vessels, coastal stations, and satellites can see them. The International Maritime Organization requires AIS on most large SOLAS ships; the technical messages are specified in ITU-R M.1371.12 The US Coast Guard’s AIS FAQ treats the fields as only as good as the last broadcast.3 That is a collision-avoidance radio, not a cargo passport and not a military roll-call.
Dark, on a public map, means the broadcast did not arrive — or did not arrive as a tanker this session. The transponder may be off. It may be intermittent. The hull may never have sent a type 80–89 static report that this client could confirm. Coverage can thin away from coastal receivers; satellite AIS fills ocean gaps and is still a sample. Voyage text — destination, draught, even the type code — is crew-entered. Analytics desks often revise an earlier print when a dark leg is confirmed later and backdated. The first number you saw was not a lie. It was incomplete, and the revision is not a new ocean.
OilRoutes does not close that gap. It is a visualization layer over AISStream.io, relayed through a Cloudflare Worker so the API key never sits in the browser. The stack note is how the map works. Positions belong to the provider. Homepage / stays the product.
Why public maps undercount
Four ordinary reasons, none of them a hidden OilRoutes filter:
- Silence. A hull that is not broadcasting cannot be plotted. Wartime and sanctions traffic often goes dark. A public map cannot tell motives apart, and this page will not teach anyone how to create the silence.
- Coverage. Coastal AIS is line-of-sight VHF. Satellite AIS helps and does not make every ocean cell a census.
- Filter. OilRoutes keeps AIS types 80–89 and optional type 35. A military or operational tally that counts craft outside that band will not match the live strip. Size nicknames such as VLCC are market language, not a map filter — see tanker types.
- Revision. A desk that later confirms a dark crossing will raise yesterday’s print. The live map never had that hull to count.
Hormuz 2026 is the worked example — link, do not re-scrape
Mid-August 2026 Hormuz traffic is already written. The National, citing Kpler, recorded dark crossings and Iranian-controlled routes after the Islamabad memorandum expired. Reuters, via Gulf Business, noted that some ships may pass with transponders off. Windward described AIS-dark ADNOC-affiliated examples in the same week’s attack file.4 Those are named-outlet caveats on the Strait of Hormuz tanker traffic 2026 note. This page will not reprint the integers, the dark-share language, or the backlog as if OilRoutes measured them. Quote the Hormuz note; follow the outlets it cites.
A transponder-off crossing is still a crossing. It is not one a public map can count with confidence. Do not treat the live Hormuz strip as a daily transit ledger. That sentence is the Hormuz note’s own limit — this hub exists so a reader does not have to re-learn it at every box.
Direct answer
What does OilRoutes show when tankers go dark near Hormuz or other chokepoints? Visible AIS only. The chokepoint integers are live counts of tracked AIS oil-tanker hulls whose latest position falls inside named map boxes — not barrels per day, not official throughput, and not a historical average. Dark or silent hulls are missing by design of the data, not by a hidden filter the site can flip on. For dated 2026 Hormuz caveats — Reuters on transponders off, The National/Kpler on dark and Iranian-controlled routes, Windward on AIS-dark ADNOC-affiliated examples — read the Hormuz 2026 note and the outlets it cites. Do not treat the live Hormuz strip as a daily transit ledger.
What OilRoutes shows
The map plots tankers that broadcast types 80–89, plus optional military type 35 as country-flag pins. Other ship types are dropped. A hull is “in zone” when its latest AIS position falls inside one of the eight rectangles in js/chokepoints.js. The integer on the stats strip is those tracked hulls, right now. Geography of the boxes is the eight oil-transit boxes.
Visible AIS only. Silent ≠ zero real traffic. The site cannot flip a “show dark hulls” switch, because it never received the messages. A quiet Hormuz, Suez, or Bab-el-Mandeb box is “no tracked AIS in this rectangle,” not proof that the waterway is empty.
Map honesty checklist
- The number is “tracked AIS oil-tanker hulls in this named rectangle now.” It will move as messages arrive and as stale tracks drop.
- Do not copy the panel’s “avg flow” string. That label is not a dated EIA or Kpler print and not a citeable OilRoutes series.
- The map does not filter VLCC, Suezmax, Aframax, or any DWT class. It does not receive draught.
- Assume undercount. Dark or silent hulls are missing by design of the data.
- Demo Mode is labeled and is not live AIS. Do not use a demo fleet to invent a dark-fleet census.
How the camera flies is how the map works. How extra days become freight and a crude risk premium — without inventing a dollar — is the markets and freight note.
Open the live map / fly to Hormuz →
Spoofing and STS are news-desk patterns, not a hunt
Desks also talk about spoofed positions — a broadcast that is not where the hull is — and about ship-to-ship transfers that can make a public map look empty or parked in the wrong basin. Those are names for why a live picture and a later confirmation can disagree. They are not a recipe. This page will not teach spoof detection, will not draw invented gap midpoints, and will not publish STS hotspot coordinates as OilRoutes findings.
Commercial dark-fleet and maritime-risk desks — Oxint, SynMax, Digital Detective, SOCRadar, and peers — sit in a different category from a public AIS visualization. This page names them so a reader can tell the genres apart. It will not teach their methods, will not rank them, and will not turn OilRoutes into a shadow-fleet tracker.
Direct answer
How should I use the OilRoutes map next to a “dark fleet” or “counts don’t match” headline? Open the live map, fly to the named chokepoint — often Hormuz — and read the claim before the integer: dark transit, backdated confirmation, or a military/operational tally that may count craft commercial oil trackers filter out. Treat the in-zone number as tracked AIS hulls broadcasting inside that box right now. Assume undercount. Sourced 2026 dark-transit language: the Hormuz 2026 note. Field meanings: how to read live AIS. Stack limits: how the map works. Substitute geography after a constrained Gulf exit: Bab el-Mandeb, Suez/SUMED, Cape, or Malacca — without promoting any live count into a desk mb/d or a price.
How to use the map next to a “counts don’t match” headline
- Name the waterway. Fly the matching box. The eight rectangles are on the chokepoints note.
- Read the claim — dark transit, backdated confirmation, military tally, spoof, STS — before you read the integer.
- Treat the number as tracked AIS hulls broadcasting in that box right now. Assume undercount.
- If the story is 2026 Hormuz dark-transit language, open the Hormuz note. Do not paste its shares onto Bab el-Mandeb, Suez, or Malacca.
- If the story is substitute geography after a constrained Gulf exit, use the sister hubs in the table — not a live count promoted to mb/d.
- If the story is a freight rate or a crude spot, go to the outlet that printed it. The EIA strip, when live, is Brent/WTI — not a dark-fleet premium.
| If the headline is… | Open this note |
|---|---|
| Dark fleet / undercount / “counts don’t match” | This page; then AIS literacy |
| Hormuz geography, pipeline bypasses, AIS box ≠ EIA flow | Strait of Hormuz oil chokepoint |
| Hormuz 2026 dark transit, transponders off, Iranian-controlled routes | Hormuz tanker traffic 2026 |
| MMSI, status, destination, Demo Mode | How to read live AIS |
| Basemap, types, water-mask, EIA strip | How the map works |
| Yanbu / southern Red Sea door | Bab el-Mandeb hub |
| Oil via Egypt, VLCC lightening, SUMED | Suez Canal and SUMED hub |
| Africa rounding after a closed Gulf or Red Sea exit | Cape reroutes 2026 |
| Asia-lane / Malaccamax | Strait of Malacca hub |
| Freight or a crude risk premium without a dollar print | Routes, markets, freight |
Demo Mode is a separate trap. Simulated hulls can sit in a box while the EIA strip is still dashes, or the reverse. Cite OilRoutes for what the map shows. Cite AISStream.io for positions. Cite the named dated outlets on the Hormuz note for 2026 dark-transit language. Never cite this article as a dark-share series, a ship count, or a price.
What this page will not do
It will not replace the live map. Homepage / stays the product. It will not invent dark-share percents, ship counts, mb/d, dollars per barrel, freight rates, voyage days, spoof coordinates, or STS hotspots. It will not re-scrape the Hormuz 2026 note, teach OSINT or gap-hunting, or turn Oxint, SynMax, Digital Detective, or SOCRadar into a method list. Silent is not zero. Visible AIS is all this map has.