Operations overview
Both major passages in the Gulf are effectively closed to normal commercial oil tanker traffic, for different reasons on each side. Hormuz did not record any tanker crossings on July 27, as all six transits were through the Northern Corridor controlled by the IRGC. Bab al-Mandab crossings have decreased by 22% since the Houthi blockade was announced on July 20, with tanker crossings declining by 39% and crossings linked to Saudi Arabia by 46%.
The mechanisms vary. The Strait of Hormuz has been closed by IRGC enforcement, the continued presence of IRGC high-speed ships in the southern strait, and the choking of the northern passage. Bab el-Mandeb is closed due to a Houthi blockade supported by the withdrawal of Lloyd’s Market insurance for Saudi-linked vessels, which took effect on July 24 and was assessed as the main driver of the largest decline in tankers.
The Iranian and Saudi crude oil prices are still moving, but under changed circumstances. On the Iranian side, 102 potential blockade-breaking ships are lined up across three levels, with five Tier One candidates located about 65 nautical miles from the blockade line, and two ships assessed as having already crossed undetected. On the Saudi side, the King Fahd Industrial Port in Yanbu operates in complete darkness with continuous loading throughput, and three China-linked VLCCs have crossed Bab al-Mandab loaded from Yanbu, indicating that Chinese oil shipments have received an exemption from the Houthi blockade.
Windward assesses the operational risk environment across the Strait of Hormuz, Gulf of Oman, northern Arabian Gulf, Red Sea, and Bab el-Mandab as critical, with the two major Gulf lanes effectively closed to normal commercial tanker traffic, active kinetic threats on both fronts, and worsening enforcement and evasion patterns across the broader region.
Hormuz is effectively closed to tanker traffic
July 27 recorded a total of 6 crossings, 3 inbound and 3 outbound, all via the Northern Corridor with no tanker crossings in either direction. The incoming group consisted of a Marshall Islands-flagged bulk carrier and an Iranian-flagged cargo ship broadcasting AIS, along with one dark contact. The outbound group consisted of a Hong Kong-flagged freighter and a Gambian-flagged freighter to broadcast AIS, along with one dark contact.
EO imagery collected over the strait on July 27 at 09:47 UTC confirmed the presence of a squadron of 6 IRGC high-speed boats in the southern strait, a dark-colored bulk carrier anchored within an active transit lane, a dark tug about 40 meters long, a dark general cargo ship about 87 meters long moving outward, and one incoming general cargo vessel matched by automated GPS (AIS) 72 meters long with a high-speed ship alongside.
A separate cluster of explosive ordnance over the Western Corridor at 06:48 UTC identified a dark LPG carrier in ballast that was assessed as stable through at least two consecutive assembly cycles, and a dark bulk carrier that was assessed as transiting inland toward Iran’s EEZ or Iranian-controlled Northern Corridor.
A previous grouping on 27 July at 03:49 UTC over the Ras Al Khaimah approach corridor identified two dark vessels crossing inland into the Arabian Gulf, consisting of a dark general cargo ship approximately 160 meters long and a dark VLCC-class tanker approximately 333 meters long.
The exclusive use of the Northern Passage for all transit operations, the complete absence of tanker transit, and the continued presence of IRGC high-speed ships in the Southern Strait ensure that the Strait remains effectively closed to commercial tanker traffic.
102 would-be blockade breakers line up
Windward evaluated 102 potential ships to break the blockade on July 27 across three levels. Five ships were assessed as Tier 1, meaning they were imminent, within about 65 nautical miles of the blockade line with confirmed loaded intent towards a true destination across the ocean.
A 110-meter, Norwegian-flagged OFAC oil tanker has been upgraded to Tier 1 after Vortexa confirmed that its declared destination of Djibouti concealed an actual diesel cargo of about 63,900 barrels actually bound for Port Klang, Malaysia, about 62 nautical miles upstream. The Guinea-flagged crude oil tanker carrying nearly 443,000 barrels of Iranian heavy crude declared bound for Karachi, but confirmed by Vortexa to be bound for Longkou, China, about 58 nautical miles downstream, is drifting at near zero speed in floating storage mode.
An Iranian-flagged bulk carrier approximately 51 nautical miles from the line, which had not moved for over a week, with erratic AIS behavior consistent with position tampering, briefly crossed the blockade line in mid-July and returned to the same threshold position. The Iranian-flagged supertanker, about 320 meters long, has been in the dark for 6 days and was last confirmed about 62 nautical miles from the line, carrying approximately 2.01 million barrels of Iranian heavy crude to Dongjiakou, China, the largest single cargo on the watch list. A fifth ship, about 63 nautical miles upstream, has been confirmed by Vortexa as carrying cargo within Iran to Chabahar, and poses no active blockade threat despite its proximity.
Two ships were assessed as having already crossed the blockade line undetected. A Comoros-flagged tanker and a Curacao-flagged tanker loaded genuine long-haul cargo of Iranian origin to Taiwan and China respectively about a week ago, and the AIS has gone dark since departure, and both were assessed as having crossed the line undetected.
Five Tier 2 vessels remain between 65 and 250 nautical miles from the line with credible offshore intent, including a 330-metre Marshall Islands-flagged VLCC bound for Jask, Oman, and a 106,000 dwt Palau-flagged crude oil tanker bound for Sohar, Oman. Vortexa confirmed that three vessels previously flagged as candidates – an Iran-flagged tanker subject to OFAC sanctions, a Comoros-flagged tanker, and a Marshall Islands-flagged tanker – were identified as short intra-Gulf movements to Fujairah or Sharjah and were removed from the list.
The Houthi siege across the Red Sea intensifies
The Houthis continue to resume escalation. The Houthi blockade on ships linked to Saudi Arabia, which took effect on July 20, led to a rapid and measurable trade response through the Red Sea corridor.
Bab al-Mandab crossings have decreased by 22% since the blockade was announced on July 20, from about 47.8 ships per day before that to about 37.2 ships per day afterward. Tanker crossings fell by 39%, and crossings linked to Saudi Arabia fell by 46%, the largest decline of any group tracked. The decline in tankers increased specifically after the release of the war risk insurance report on July 24, falling to about 7.5 tankers per day compared to about 12 tankers per day immediately after the announcement of the blockade. Crude oil tankers slowing down or backing up near the Gulf of Aden exit have risen 138% since July 19, and now number 13 vessels, assessed as vessels holding position rather than committing to the lane.
10 ships left Yanbu last week carrying Saudi crude, products and liquefied petroleum gas to China, India, Pakistan and Japan, all via Bab al-Mandab.
Wind direction early detection data shows that oil and chemical tankers undertaking darkening activity in the Saudi Red Sea increased by 144% during the period from July 19 to 26, and was assessed as a security response associated with ships calling ports in Saudi Red Sea ports and then darkening.
Windward identified 158 vessels across five criteria potentially vulnerable to Houthi targeting, including 4 Saudi-flagged vessels, 11 Saudi-owned vessels navigating the Red Sea and Gulf of Aden, 9 VLCCs and offshore-type bulk carriers crossing the Arabian Sea westward, 11 vessels on Red Sea flows tracked by Vortexa through the corridor, and 123 vessels that stopped at Saudi Red Sea ports between 23 and 25 July. Then it got dark between July 23 and 23. 26. Two of Bahri’s VLCCs are currently showing AIS positions within Yemeni waters, directly within the Houthi engagement zone.
Three Chinese-owned VLCCs transited Bab al-Mandab without incident from July 23 to 24, consistent with the Houthis’ allocation of ships linked to China and Russia. A Hong Kong-flagged supertanker carrying nearly 2 million barrels of crude oil loaded in Yanbu with an active automatic identification system passed towards Ningbo, China. This is the third China-linked VLCC to cross the region in two days despite the blockade imposed on shipments of Saudi origin, indicating that Chinese oil shipments loaded from Yanbu have received an exemption.
Lloyd’s withdraws war risk cover from ships linked to Saudi Arabia
Insurers in the Lloyd’s market are excluding ships with Saudi links from war risk coverage, including ships that have only stopped at a Saudi port in the past, pushing the trade back towards the pre-2024 pattern of requiring HOCC permission before transiting. The insurance withdrawal took effect from July 24 and was assessed as the main driver of the sharp decline in tanker crossings through Bab al-Mandab, which fell to about 7.5 per day after the story broke, from about 12 per day immediately before.
Stems operate in complete darkness with continuous load productivity
EO imagery collected over the King Fahd Industrial Port in Yanbu on July 28 across two passes, at 05:09 UTC and a clearer set at 07:39 UTC, confirmed that all vessels at the dock and in the holding area were operating in the dark with no AIS transmission, an ongoing trend assessed as safety driven to avoid association with targeting of Saudi Arabia and the Houthis.
The 07:39 UTC array, which was taken under clearer conditions than the previous pass, identified 22 ships in total. Twelve vessels performing active cross-berth loading were evaluated, consisting of 7 tankers ranging in length from approximately 144 to 339 meters and 5 bulk carriers ranging in length from approximately 180 to 229 metres. Ten dark-colored oil tankers were parked in the waiting area. Two carriers in this group have been confirmed to have departed, confirming the presence of an active loading cycle. A dark tanker about 339 meters long was recently discovered at the pier in the corridor at 07:39 UTC, and was not visible in the previous group due to cloud cover. Three oil tankers in the waiting area were new arrivals. At least one tanker departed on 27 July, with two departures confirmed the previous day, confirming continued productivity.
The transition from active AIS operations to fully dark AIS operations reflects ships effectively turning off AIS as they approach port to protect themselves from a list of Houthi targets targeting Saudi-linked ships.
Kharg Island LPG terminal sees new arrivals and decrease in frequency
EO images collected over Kharg Island on July 27 at 08:08 UTC showed a dark tanker about 185 meters long newly arriving at the LPG terminal, which was not present in the previous group. It was confirmed that the eastern and western stations were empty. The eastern holding area contains only two dark stationary tankers, including a laden vessel of approximately 249 meters in length assessed as having been present since 12 July, and a ballast vessel of approximately 180 meters in length assessed as having been present since 14 May. The frequency of ships arriving at the LPG terminal is decreasing.
Expectations
Two Gulf lanes are now effectively closed to normal commercial oil tanker traffic simultaneously. The Strait of Hormuz has been closed by IRGC enforcement and a bottleneck in the Northern Passage. Bab al-Mandab is closed by a Houthi blockade supported by the withdrawal of Lloyd’s war risk insurance from Saudi-linked ships. Both produce the same operational outcome, with tanker crossings collapsing, dark activity increasing, and evasion tactics spreading across the broader fleet.
The Iranian and Saudi crude oil prices are still moving under changing conditions. On the Iranian side, 102 potential candidates to break the blockade are lined up across the line, with two of them assessed to have crossed undetected. On the Saudi side, Yanbu is operating in complete darkness with continuous loading throughput, and the China-linked cargo has received an exemption from the Houthi blockade, which is now clearly transporting crude oil loaded from Yanbu eastward via Bab al-Mandab.
Windward assesses the operational risk environment across the Strait of Hormuz, Gulf of Oman, northern Arabian Gulf, Red Sea, and Bab el-Mandeb as critical, with both major lanes effectively closed to normal commercial tanker traffic, active kinetic threats on both fronts, structurally elevated dark activity across the region, and China-related tonnage now clearly operating under differential rules on both fronts.
Source: Blowing in the Wind
