A month and a half into the war between Iran and the US and Israel, one thing has kept showing up in the data: ships that vanish.
Disappearing transponders and the “shadow fleet” problem
Michelle Wiese Bockmann, a senior maritime intelligence analyst at Windward AI, has tracked shipping across the globe for 30 years, and she says the Strait of Hormuz has always had its share of disappearances.
For nearly a decade now, “shadow fleets” engaged in shady practices—like violating international sanctions by transporting crude oil from Iran—have periodically turned off their transponders.
Those devices usually broadcast ships’ names, locations, routes, and IMO (International Maritime Organization) numbers, including the unique, seven-digit IMO identifier that lets trackers trace vessels over time.
But jamming and “spoofing” transponder signals isn’t new.
What is new, or at least newly amplified, is the scale.
Misryoum newsroom reporting says that at one point last month, “well over half of the vessels in the strait had their signals jammed,” and today, more than 800 vessels are in the Persian Gulf, according to Windward AI data.
How analysts keep following tankers
Bockmann and other analysts aren’t just staring at gaps anymore—they’re building ways around them.
She describes keeping “a very, very close eye on a large cohort of 500 or 600 tankers,” some of them tracked for years, and once a ship’s identity is pinned down it’s like a sudden moment of recognition: “Ah, I see you.” It’s a cat-and-mouse game with real consequences.
Misryoum analysis indicates that Windward AI works with marine insurers, oil traders, and other financial institutions that have interests in or onboard one of hundreds of ships moving through the Strait of Hormuz every month (in times of relative peace).
About 20 percent of the petroleum consumed globally moves through the narrow waterway, and Bockmann has used the phrase “absolute carnage and chaos” to describe what disruption there can mean.
The stakes aren’t only financial or long-term, either.
Tankers that aren’t accurately broadcasting their locations can crash into others or run aground, which would raise the likelihood of catastrophic oil spills.
And when the world is this tense, the work can feel… relentless.
Bockmann said she had to cut short a visit with her family in Australia after Israel and the US attacked Iran in late February.
Back in London, she’s been working long days ever since—one day blending into the next.
You can almost hear it in the way she talks about the constant churn of data.
Eye-level tracking has also shifted.
Samir Madani, the cofounder of TankerTrackers.com, has long relied on satellite imagery from both commercial and public sources, aiming to give paying clients a clearer view of when and where oil and other goods are moving in and out of the strait.
In April, US satellite firms announced they would limit high-resolution imagery of the region, and Misryoum newsroom reported that Madani said, “We are dusting off all the old sources and tweaking them to perfection,” adding that the firm was buying information from other Western sources as well.
The underlying point is blunt: two-thirds of tanker traffic moving through the Strait of Hormuz is by vessels with histories of violating sanctions, so the data pipeline matters.
To fill in the blanks, Bockmann’s firm leans on several technologies at once.
Electro-optical imagery uses sensors to detect visible and near-infrared light.
Synthetic-aperture radar uses microwaves to create images even through clouds, rain, or darkness.
Radio-frequency signals can help transit data wirelessly, including familiar styles of connectivity like Wi‑Fi, Bluetooth, and GPS.
Then the signals get stitched to databases with ship registry information—and even “human presence signals” from mobile devices onboard vessels.
Generally, satellite imagery used to be very expensive to obtain, but prices are coming down.
So, yeah, if you’re going to chase spoofers, you probably can’t do it with one tool alone—at least not right now.
And somehow, the chase keeps going, even when the coverage narrows, the maps glitch, and the ships keep “going missing” and reappearing somewhere they’re not.
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