Resolving Charter Disputes When Vessels Go Dark in the Strait of Hormuz

At a Glance

• The Strait of Hormuz has operated outside normal parameters since the launch of Operation Epic Fury, with visible AIS transits down 83% year-on-year in June 2026 and a growing share of remaining traffic transiting with AIS switched off.
• Legal commentary through 2026 has flagged rising charter dispute exposure tied to Hormuz transits, with force majeure, frustration, safe-port warranty, and AIS switch-off questions all now surfacing as litigation-relevant.
• A recurring dispute pattern has emerged, in which a vessel enters the Hormuz war-risk zone, switches off AIS for a defined window, and the charterer alleges that during the dark period an unreported ship-to-ship transfer, unscheduled port call, or cargo diversion occurred.
• The BIMCO AIS Switch Off Clause for Time and Voyage Charter Parties 2021 shifts the analytical center of gravity from whether AIS was switched off to what actually happened during the dark window, making forensic reconstruction of vessel behavior the decisive evidentiary question.
• Reconstructing vessel activity during a dark period is a multi-sensor intelligence exercise, drawing on satellite imagery, radio frequency detection, and behavioral pattern analysis to establish what a vessel likely did when it stopped self-reporting position.
• Windward’s Remote Sensing Intelligence and Maritime Intelligence Operations Center reporting provides the forensic infrastructure counsel and arbitrators need to move disputes from competing affidavits to documented reconstruction.

The Legal Landscape Is Shifting

Legal commentary on Strait of Hormuz-related maritime disputes has grown consistently through 2026. Holland & Knight’s March 2026 analysis flagged the rising risk of charter disputes as the Hormuz disruption continued. Skuld’s charterparty implications has addressed the AIS switch-off question directly, alongside force majeure and safe-port warranty considerations. P&I clubs have circulated member guidance on the operational and contractual questions Hormuz transits are now raising.

The themes are consistent across the commentary. Force majeure and frustration arguments are being tested against an operational environment that does not resemble the assumptions most charterparties were drafted under. Safe-port warranties are being scrutinized when the ordered port sits within or near an active war-risk zone. AIS switch-off decisions are being contested when the operational rationale for them is unclear or the consequences ambiguous.

The disputes are not hypothetical. Legal commentary through 2026 has flagged a rising volume of disputes working through arbitration, court proceedings, and pre-litigation counsel review in numbers that were not visible before the current crisis.

The Hormuz Backdrop

The operating environment behind these disputes has changed structurally. Following the outbreak of the Iran conflict on February 28, 2026, visible AIS transits through the Strait of Hormuz collapsed. February 2026 recorded approximately 3,750 AIS-visible monthly transits. March fell to 450, April recovered to 630, then May dropped again to 450, and June reached 640. Even after the partial recovery, June remained approximately 83% below the pre-conflict baselines.

Traffic began to rebound in the final weeks of June following a Memorandum of Understanding between Iran and the U.S. and the expansion of a U.S.-supported southern corridor through Omani waters. Daily transits climbed from an average of nine in the first two weeks of June to 43 in the final week. On June 24, the day after the International Maritime Organization announced an evacuation corridor along the southern route, observed transits peaked at 61 vessels. The corridor was suspended two days later following Iranian attacks on ships.

War-risk premiums for Hormuz transits have moved accordingly, rising from roughly 0.25% of hull value in the pre-conflict period to 3-10% of hull value at various points through 2026, according to insurance market coverage. 

Against this backdrop, a growing share of vessel traffic through the Strait is transiting with AIS switched off, or showing dark or unexplained routing. Many vessels are switching AIS off with owner and flag state consent for security and safety reasons, particularly for stranded vessels exiting the region through the southern corridor. Others are switching off for reasons that are less clear or more contested.

The Scale of Dark Transits

Dark transits through the Strait of Hormuz are a regular and quantifiable feature of the current traffic pattern. Windward has tracked dark transits through the Strait of Hormuz since the outbreak of the Iran conflict, with volumes fluctuating day to day.

The July 28 pattern is particularly instructive for counsel. On that single day, Windward tracked 16 inbound AIS-visible transits, 8 outbound AIS-visible transits, and 17 dark transits. Dark traffic on that day exceeded either category of visible traffic. Across the surrounding weeks, dark transits fluctuated day to day but consistently formed a meaningful share of overall Hormuz throughput.

The operational implications for dispute exposure are direct. Every dark transit is a defined window during which vessel activity was not self-reported. Some of those transits will pass without incident or dispute. Others will not. In a traffic environment where dark transits are a routine feature rather than an exception, the number of charter and cargo relationships that pass through a dark period during the life of a Hormuz voyage is substantial and growing.

The Dispute Pattern

The dispute pattern emerging in charterparty and cargo litigation follows a recognizable arc.

A charterparty is in place. The vessel enters or approaches the Hormuz war-risk zone. AIS is switched off for a defined window, framed by the owner as a safety or security measure. When AIS is restored, the vessel’s position, cargo condition, or operational status appears inconsistent with what the charterer had expected.

The charterer then alleges that during the dark window, one of several things occurred: 

• An unreported ship-to-ship transfer may have taken place, with cargo diverted, contaminated, or partially removed. 
• An unscheduled port call may have been made, exposing the cargo or the vessel to risk the charter did not authorize. 
• A deviation from the ordered voyage route may have concealed a purpose the charterer did not sanction.

The owner’s position typically holds that the AIS switch-off was legitimate under the operational conditions of the Hormuz war-risk environment, that no unauthorized activity occurred during the dark period, and that any anomaly in cargo or vessel status has a different explanation.

The dispute becomes a charterparty claim, an arbitration, or a cargo claim on the underlying insurance. The question at the center of it is the same in each case: What actually happened during the period when the vessel was not self-reporting its position?

Why the Contract Alone Does Not Resolve It

Two features of the current environment make the contract framework, by itself, insufficient to resolve these disputes.

The first is the contested state of force majeure and frustration arguments in an active war zone. Force majeure clauses vary substantially across charterparties, and their application to the specific operational conditions of the Hormuz war-risk zone is being tested case by case. Frustration doctrine has been argued in some proceedings but has not produced consistent outcomes, particularly given the extended duration of the disruption and the shifting nature of the risk environment. Counsel operating in this environment cannot assume that either argument will resolve a dispute in favor of a particular party without the underlying facts being established first.

The second is the BIMCO AIS Switch Off Clause for Time and Voyage Charter Parties 2021. The clause requires owners to warrant that AIS silencing has not been used contrary to IMO guidance. The important effect for dispute resolution is that the analytical center of gravity shifts. The question is no longer primarily whether the vessel switched off AIS. That fact is typically not in dispute. The question is what the vessel did during the dark window, and whether the operational reality of that period is consistent with the owner’s stated rationale for the AIS switch-off or with the charterer’s allegations to the contrary.

Recent case law is also shaping the environment. The English Court of Appeal ruling in Tonzip Maritime (Singapore) Pte Ltd v 2 Rivers Pte Ltd, “The Catalan Sea” [2026] EWCA Civ 641, handed down on May 22, 2026, clarified that the threshold for invoking sanctions clauses in charterparties is a reasonable judgment of a real risk of sanctions, not proof that a breach would probably occur. The case does not directly address AIS switch-off disputes, but it signals how courts are approaching the interpretation of contested contractual terms in the current environment, and how the evidential threshold for parties invoking such terms is being calibrated.

Both features push the dispute in the same direction. The evidentiary question of what happened during the dark period becomes decisive.

Reconstructing the Dark Period

Reconstructing vessel activity during a period when the vessel was not self-reporting its position is a forensic exercise. It draws on multiple independent data sources that do not depend on the vessel’s cooperation.

Satellite Imagery

Synthetic Aperture Radar (SAR) provides vessel detection regardless of weather and lighting conditions, capable of confirming vessel position at specific times when AIS is off. Electro-optical (EO) imagery provides visual confirmation of vessel activity, including ship-to-ship transfers, port calls, and vessel proximity to other assets. High-resolution EO imagery can resolve down to 30 centimeters, allowing distinguishing features to be identified for vessel confirmation and verification of identity claims.

Radio Frequency Detection

Vessels emit RF signals from their operational systems even when AIS is off. RF detection provides an independent positioning signal that can confirm or contradict a vessel’s stated location during a dark period.

Behavioral Pattern Analysis

A vessel’s operational history, ownership pattern, prior AIS behavior, and comparative baseline against similar vessels in similar conditions all provide context that supports or challenges specific claims about what occurred during a dark window.

Multi-Sensor Fusion

When these sources are combined, they produce a reconstructed picture of vessel activity that does not depend on the vessel’s own broadcast. A vessel that claims to have transited a specific route with AIS off can be verified or contradicted against SAR imagery, RF signal, and behavioral consistency with the claimed route. A vessel that is alleged to have conducted an unreported ship-to-ship transfer can have that allegation tested against the detection record for other vessels in proximity during the dark window.

The reconstruction does not produce certainty in every case. It supports an analysis intended to support counsel’s evidentiary record of what the vessel most likely did, with the specific sensor and analytical inputs that support the conclusion.

For counsel and arbitrators, this can provide a firmer analytical footing than competing affidavits and inference from partial data alone.  

How Windward Supports Legal Investigation

Windward’s Remote Sensing Intelligence (RSI) capability that law firms and their in-house analysts can use directly to conduct dark period investigations. Remote Sensing Intelligence fuses AIS, SAR, EO, RF, and behavioral context into a single operational picture, giving counsel a structured view of vessel activity during a defined period, independently of the vessel’s own broadcast.

The Maritime Intelligence Operations Center (MIOC) provides expert analyst services on behalf of the firm. Windward’s maritime intelligence experts conduct the dark period reconstruction, apply the analytical methodology to the specific facts of the case, and produce a documented report for counsel’s use. Each MIOC report details the analytical approach, the sensor inputs relied on, the basis for every finding, and the confidence level assigned to each conclusion, giving counsel and arbitrators analysis intended to support the evidentiary record for a contested period.

For law firms handling Hormuz-related charter and cargo disputes, the operational fit is direct. Where the dispute turns on what happened during an AIS dark period, Remote Sensing Intelligence reconstructs the vessel’s likely activity against the specific allegations at issue, and MIOC reporting produces the documented, timestamped analysis counsel can draw on in proceeding.

What Counsel Handling a Dark Period Dispute Can Do

The dispute pattern outlined above is now a recurring feature of Hormuz-related litigation. Law firms handling charter disputes, cargo claims, or arbitrations tied to Hormuz transits can bring the underlying evidentiary question to a forensic partner with the sensor infrastructure and analytical capability to answer it.

Windward’s Remote Sensing Intelligence and MIOC teams work directly with legal counsel on dark period reconstruction. The output is designed to support the needs of the proceeding, whether the dispute is at pre-litigation review, arbitration, or contested court proceedings.

For counsel currently working on a Hormuz-related dispute in which an AIS dark period is central to the case, Windward is available to support the forensic reconstruction.