21SEP

Hormuz transits climb to 13 on 28 April

4 min read

15:34UTC

Windward logged 13 crossings, up from 9 on 24 April; one outbound vessel ran AIS-dark and CENTCOM revised its blockade tally to 37 vessels.

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Key takeaway

Hormuz transits climbed to 13 on 28 April; CENTCOM revised its blockade tally to 37 vessels.

Maritime intelligence firm Windward logged 13 Strait of Hormuz crossings on 28 April 2026, up from 9 on 24 April, comprising 3 inbound and 10 outbound vessels. One outbound vessel ran AIS (Automatic Identification System) dark, with its transponder switched off in a pattern the maritime trade reads as deliberate concealment. The Windward daily, sourced from satellite AIS feeds and proprietary shipping intelligence, is the most granular public record of Hormuz tempo during the blockade.

CENTCOM (US Central Command) logged 37 vessels redirected per the 25 April US forces statement on the Windward read, a downward revision from the 38 vessels counted in the 27 April reporting. The discrepancy may be a US forces revision rather than a real decline; the figure is bracketed pending the next CENTCOM statement. The Windward-sourced clarification on LPG SEVAN corrects the seizure framing carried in: the OFAC-sourced record names the vessel as sanctioned on 25 April among 19 shadow-fleet tankers, not seized at sea. OFAC (Office of Foreign Assets Control) is the Treasury bureau that administers economic sanctions; the 25 April designation was a list-rather-than-takedown action.

Iran is drafting a bilateral transit protocol with Oman to oversee Strait of Hormuz passage, and Foreign Minister Abbas Araghchi told Sultan Haitham in Muscat on 26 April that any reopening must run through Tehran's terms. The 28 April rise to 13 transits sits inside that diplomatic envelope, not outside it. Three inbound versus ten outbound implies cargo running out faster than freight running in, with shadow-fleet operators clearing existing positions before any 1 May reset. The single AIS-dark outbound continues a baseline opacity rate Windward reported running at roughly 13 per cent on 24 April; concealment tracks with the OFAC shadow-fleet designation and the wider sanctions architecture pressuring Iranian cargo carriers.

CENTCOM has logged 37 vessels redirected over the blockade and reframed the LPG SEVAN status from seizure to sanction inside three days, the tightest correction interval since the operation opened on 28 February. Brent at $111.16 sets the price record running alongside the operational tempo, and Windward's daily Hormuz transit count carries the only granular public ledger sitting between the two.

Deep Analysis

In plain English

the strait of Hormuz is a narrow channel through which around a fifth of all the world's oil normally passes. Before the war started, about 135 ships transited each day. On 28 April, only 13 ships made the crossing, according to the tracking company Windward. That is roughly 10% of normal traffic. One of those ships turned off its tracking signal, which tanker operators do when they want to avoid being detected. The slow traffic is why oil prices are so high: the world's most important oil route is nearly completely blocked.

What could happen next?

Consequence
CENTCOM's revised tally of 37 vessels redirected (down from 38) represents the first downward revision of the blockade figure since enforcement began, which may reflect a deliberate US forces communications correction rather than any actual change in enforcement intensity.
Risk
AIS-dark transits, as documented on 28 April, reduce CENTCOM's situational awareness of actual vessel movements through the strait, creating potential for miscalculation if an untracked vessel crosses the US enforcement perimeter without prior identification.

Source Landscape

This story draws on neutral-leaning sources from Israel

Israel

Primary parallel: The 1984-87 Tanker War in the Iran-Iraq conflict is the most structurally comparable period of Hormuz interdiction. At peak interdiction intensity in 1987, roughly 37 vessels were attacked in the strait over the year, with Lloyd's of London applying a 25-30% war-risk premium to Gulf hulls.

Transit volumes dropped by approximately 15-20% from baseline during peak months but never collapsed below 60% because neither belligerent could physically close the strait. The 2026 conflict has pushed transit volumes to 10% of baseline, a far deeper disruption, because CENTCOM's blockade enforcement adds a second-layer interdiction effect on top of Iranian mine and seizure risk.

Counter-parallel: The 1984-87 Tanker War did not involve a US Navy blockade enforcement mechanism. The current 90% traffic reduction reflects the additive effect of two enforcement regimes, CENTCOM blockade plus IRGC interdiction, operating simultaneously in the same waters, which has no direct historical precedent in Hormuz interdiction history.

At 13 transits against a 135-per-day baseline, the Hormuz disruption removes approximately 18-19 mb/d of potential throughput from global markets daily. Kpler's flow data shows shadow fleet routing of Iranian crude at roughly 1.2 mb/d reaching Chinese refiners, and Saudi Aramco has rerouted some Red Sea and Yanbu export volumes to non-Hormuz paths.

IEA's April 2026 Oil Market Report estimated the net supply disruption at 6-8 mb/d after accounting for rerouting and shadow fleet volumes. That net figure, rather than the gross 18-19 mb/d transit loss, sets the realistic price-support floor: a Hormuz reopening would remove the gross scarcity signal but the net disruption has already been partially absorbed by alternative routing, meaning a ceasefire-day Brent drop would likely settle at $85-95 rather than returning to the pre-war $63 baseline.

Consensus view: Vortexa's maritime analytics team notes that the 13-transit reading on 28 April sits within the 9-16 range that Windward has documented across the preceding week, suggesting the strait has stabilised at a new constrained equilibrium rather than continuing to decline.

Vortexa's model places genuine throughput capacity at 20-25 transits per day under current IRGC enforcement conditions, implying 7-12 transits per day are being suppressed by a combination of US blockade enforcement and Iranian interdiction risk.

Counter-view: Kpler's AIS analytics division argues the official transit count systematically understates actual throughput because AIS-dark vessels, like the outbound tanker on 28 April, are not captured in Windward's transit figures. Kpler's synthetic-aperture radar data for the same period suggested 2-4 additional uncounted vessels transiting per day under AIS suppression, meaning the true transit figure may be 15-17 rather than 13.

Key tension: Whether the 13-transit reading represents a genuine operational floor set by enforcement activity, or whether AIS-suppression is enabling a parallel dark-transit corridor that US and Iranian surveillance cannot fully monitor, making the true throughput figure systematically higher than public transit counts suggest.

First Reported In

Update #83 · UAE quits OPEC, war signs nothing

Windward· 29 Apr 2026

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Causes and effects

Caused by

Brent closes at $105.73, dark activity rises

Hormuz transits rose to 13 on 28 April, up from 9 logged on 24 April.

Occurred 24 Apr 2026

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This Event

Hormuz transits climb to 13 on 28 April

Hormuz transits at 13 sit at roughly a quarter of the pre-war daily baseline, but the move higher matters: it tracks Iran's revised ceasefire signalling and the Pakistan mediator track, not a CENTCOM relaxation. The CENTCOM tally of 37 vessels redirected, revised down from 38 logged on 27 April, tightens the operational record alongside the LPG SEVAN seizure-versus-sanction correction.

Led to

CENTCOM blockade hits 44 vessels, 69m barrels

Adm Cooper's 44-vessel count directly escalated from the 38 logged on Day 60

Occurred 30 Apr 2026

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Different Perspectives

Office for Budget Responsibility

The OBR's 28 October forecast assumed $82 oil for 2026 and 2027, from market prices for the ten working days to 19 August, and blamed dearer wholesale energy on the war without naming Iran. It expects CPI inflation close to 4% in early 2027 even at that price.

Hengaw, Kurdish rights group

Hengaw reported the 3 November hangings of Amirhossein Maleki and Amirhossein Ebrahimi in Isfahan, saying Ebrahimi was tortured into confessing and that nine of 12 people sentenced to death in the case have now been hanged. Iran's judiciary holds that the defendants killed members of the security forces.

FINTRAC, Canada's financial intelligence unit

FINTRAC worked with the US Treasury on the 6 November designation of eight money services businesses in British Columbia, Ontario and Quebec. Treasury says the businesses still operate, some under new names, so closing them falls to Ottawa.

Abdul Qadir al-Dakhil, Governor of Nineveh

Al-Dakhil cancelled three Mosul International Airport contracts on 7 November over alleged links to armed groups, after meeting Prime Minister Ali al-Zaidi in Baghdad. He named no group or company, and said the contracts will go to international companies.

Kuwait

Kuwait condemned the Houthi missile fired towards the Madinah region on 5 November and restated its support for Saudi Arabia, the Qatar News Agency reported. Its state tanker company, Kuwait Oil Tankers Company, is among the Gulf state fleets on Iran's expanded Hormuz list.

Scott Bessent, US Treasury Secretary

Treasury designated an alleged Chandigarh false-flag network on 4 November and eight Canadian exchangers on 6 November, while State sanctioned alleged MANPADS intermediaries. None of the actions touches an oil buyer; they target the paper, cash and procurement around Iran's trade.

Written with AI from Lowdown's published reporting. Not individually reviewed by an editor. Editorial standards.