How to control ship-to-ship transfer risk across regimes

A cargo owner dispatching a vessel to a mid-ocean rendezvous point receives a late message: the receiving vessel has gone dark on AIS, and a broker confirms the transfer will proceed ship-to-ship, away from any port. The commercial case looks sound. But every major sanctions regime – OFAC, OFSI, the EU Council regulations, and the Swiss SECO framework – treats an unexplained AIS gap in a transfer operation as a red flag that, left unresolved, can expose the cargo owner, the insurer, the ship manager, and the charterer simultaneously. As of January 2026, enforcement posture across all these regimes has hardened, and the consequences of a single uncontrolled ship-to-ship transfer can cascade across multiple legal systems at once.

Controlling ship-to-ship transfer risk (the sanctions and export-control exposure that arises when cargo changes vessel at sea or at anchor, outside a regulated port) requires a structured, multi-regime check applied before the transfer is authorised, not after it completes. The governing authorities are OFAC (for US-nexus parties and USD transactions), OFSI (for UK-nexus parties), the EU Council (for EU-incorporated entities, EU-flag vessels, and EU-currency transactions), and SECO (for Swiss-nexus parties). All four regimes treat AIS manipulation, unexplained transfer geography, and unverified receiving-vessel insurance as objective diversion indicators – and in our cross-border practice, the most dangerous transfers are exactly those where more than one regime applies simultaneously.

This guide walks through five sequential steps for controlling ship-to-ship transfer risk across a multi-regime footprint: from pre-fixture intelligence gathering, through AIS and insurance verification, to ownership-chain screening, contract structuring, and post-transfer record-keeping.

Step 1: Establish which regimes apply before the fixture is signed

The threshold question – before any vessel or cargo check begins – is which regimes have jurisdiction over this transfer. A transfer between two non-US, non-UK, non-EU parties can still engage OFAC if the cargo, the financing, or any intermediary payment is denominated in US dollars, or if a US person is involved anywhere in the chain. It can engage OFSI if a UK-incorporated company, a UK-flag vessel, or a UK-national crew member participates. It can engage the EU Council rules if an EU-incorporated ship manager, a vessel flying an EU member-state flag, or an EU-currency payment is in the transaction.

In our experience, the single step that most consistently prevents a late-stage deal collapse is running the jurisdictional map at fixture stage, not at bill-of-lading stage. By the time a bill of lading is issued, the cargo owner may already have facilitated a prohibited transaction. The practical tool here is a short nexus checklist: nationality and incorporation of every principal, flag state of both vessels, currency of all payments, domicile of the insurer, and the routing of any correspondent banking leg.

Where the SECO framework applies – as it frequently does for European trading houses with Swiss treasury arrangements – note that Switzerland aligns closely with EU measures in substance, though the administrative mechanism differs. The stricter prohibition governs wherever two regimes both attach to the same conduct. That cross-regime principle is not a technicality. It is the operational reality that determines which control standard the compliance function must actually satisfy.

Document the nexus analysis in writing, with a named author and a date, before the fixture is confirmed. That record is a material component of the mitigation file if a question arises later.

Step 2: Screen both vessels and their full ownership chains

Screen the transferring vessel and the receiving vessel against all applicable consolidated lists before the fixture is confirmed and again within twenty-four hours of the scheduled transfer date. The relevant lists are the OFAC SDN List (Specially Designated Nationals and blocked persons), the OFSI Consolidated List, the EU Consolidated List, and the UN Security Council Consolidated List. For a SECO-applicable transaction, screen the SECO list in parallel.

Name screening alone is insufficient. Apply the 50 percent rule – the rule under which any entity owned 50 percent or more, directly or indirectly in the aggregate, by one or more blocked persons is itself treated as blocked under OFAC – to both vessels' registered owners, technical managers, commercial operators, and charterers. The EU and UK apply an ownership-and-control test that is wider in scope: a non-listed entity can be caught through a listed person's exercise of actual control, even where the direct-ownership threshold is not met. Do not stop at the first layer of the ownership chain.

For the receiving vessel specifically, verify the most recent port calls and flag-state history. A vessel that has recently changed flag, changed name, or traded into a high-risk area without an evident commercial explanation should be treated as elevated risk and routed for enhanced due diligence before fixture confirmation. In our practice, a pattern of flag-state changes within a short period, combined with an absence of public fixture history, has been the most reliable single indicator of diversion risk.

Record all screening results, the lists checked, the date and time of each check, and the name of the person who ran it. OFAC requires records of all transactions – including blocked and rejected transactions – to be kept for five years. Treat that standard as the floor across all regimes for this documentation obligation.

Step 3: Verify AIS continuity and insurance cover for both vessels

AIS (Automatic Identification System) continuity verification is not optional. Under the maritime compliance standards applied across OFAC, OFSI, and the EU Council, an AIS transmission gap of material duration – particularly in a transfer zone associated with diversion activity – is a recognised objective indicator of sanctions risk. A vessel that has gone dark before, during, or after a ship-to-ship transfer operation cannot be treated as clean absent a satisfactory technical explanation.

Obtain AIS track data for both vessels for at least the preceding ninety days. Check for gaps, positional inconsistencies, and speed-over-ground anomalies. Cross-reference declared voyage patterns against actual historical tracks. Where gaps appear, require the vessel operator to provide a written technical explanation. Power failure and technical malfunction are legitimate explanations, but they require documentation. Convenience-darkness – switching off transponders to conceal a transfer location – is not a technical malfunction, and no commercial pressure justifies treating it as one.

Insurance verification runs in parallel. A designation of a protection and indemnity (P&I) insurer can cascade directly into loss of cover for all vessels insured by that club. A charterer or cargo owner who takes delivery of a cargo transferred from an uninsured vessel may have participated in a transaction with a designated entity. Verify the P&I cover for both vessels before fixture, confirm the insurer is not designated, and confirm that the policy is not subject to a sanctions exclusion that would void it on the transfer route in question. For services related to identifying AIS anomaly indicators under EU rules, see our AIS anomaly indicators service.

Where a vessel cannot provide satisfactory AIS track data and cannot verify insurance, the correct response is to decline the transfer pending resolution, not to proceed and document the gap as a noted deficiency. Proceeding with a known unresolved indicator is the conduct that attracts the most severe enforcement treatment across all regimes.

Step 4: Structure the contract to allocate risk and preserve exit rights

Commercial contracts for ship-to-ship transfers should contain specific sanctions representations, warranties, and termination rights. A seller's contractual representations do not remove the buyer's autonomous obligations under the applicable sanctions regimes – and this is the point at which the most common myth in this practice area causes real harm. Sellers and brokers sometimes assert that strong contractual warranties from the counterparty shift the compliance risk. They do not. A warranty is a commercial remedy. An OFAC violation is a strict-liability regulatory event. Both can exist simultaneously, and the regulatory consequence is not extinguished by a contractual indemnity.

The contract should include, at a minimum: a representation that neither vessel, nor any entity in their ownership and management chains, is listed or blocked under any applicable sanctions regime; a warranty that AIS data will be transmitted continuously and uninterrupted throughout the voyage and transfer; a right to terminate without penalty if a designated party is discovered at any point before or during the transfer; a requirement to notify the other party within a defined, short period if any sanctions-relevant change of ownership or flag is made; and a record-keeping obligation on both parties.

For transactions subject to OFSI, include an explicit obligation to report to OFSI if any party forms knowledge or reasonable suspicion that a designated person has an interest in the transaction. The UK regime imposes this obligation on relevant firms regardless of any contractual arrangement. Build the obligation into the contract so that both parties understand it exists and who is responsible for discharging it.

For further detail on the OFAC-specific contract structuring steps, including the treatment of letter-of-credit and payment mechanics, see our OFAC ship-to-ship transfer guide.

Step 5: Apply post-transfer record-keeping and ongoing monitoring

A controlled transfer does not end when the cargo is delivered. Post-transfer obligations run across all the major regimes, and in our experience, the post-transfer phase is where compliance controls most often degrade – particularly in high-volume trading operations where the next fixture draws the team's attention away from a completed deal.

Immediately after the transfer, file a complete record: the fixture confirmation, the screening results for both vessels (including the ownership-chain analysis), the AIS data for both vessels covering the period from fixture to delivery, the insurance certificates and any sanctions-endorsement wording, the contractual documentation, and a brief compliance memorandum noting any elevated indicators encountered and the steps taken to address them. That file should be accessible for at least five years, in line with the OFAC record-keeping standard, which functions as a practical baseline for multi-regime transactions.

Post-transfer monitoring matters because designations are made after transactions complete. If a party involved in a completed transfer is designated after the transfer, the firm needs to know promptly. OFAC requires blocked-property and rejected-transaction reports within 10 business days of the relevant event; OFSI and the EU have their own reporting windows. A subsequent designation can transform what was a clean transaction into one that requires a disclosure filing. Automated monitoring of the ownership chain is the operationally realistic way to catch this; manual re-screening of completed transactions is typically not sustainable at volume.

For transactions with a Swiss nexus, the SECO framework should be checked in parallel throughout the post-transfer monitoring period. For detailed guidance on the SECO-specific steps, including alignment with EU measures and divergence points, see our SECO ship-to-ship transfer guide.

Risk flags that require counsel before proceeding

Certain indicators should pause a transaction and prompt legal review rather than a compliance-team resolution. The list below reflects the patterns we most regularly see in cross-border ship-to-ship transfer matters where enforcement risk has materialised or where a transaction has had to be unwound.

The first is an unresolved AIS gap on the receiving vessel. If the operator cannot explain a material gap with contemporaneous technical documentation, the risk is unquantifiable until the explanation is verified.

The second is an ownership chain that terminates in a jurisdiction associated with high diversion risk, without verified beneficial-ownership documentation. A chain that runs through two or more intermediate holding companies in non-transparent jurisdictions is a structural red flag, not a routine compliance matter.

The third is a transfer request at unusually short notice combined with an instruction to use an unfamiliar broker or a non-standard payment route. Speed and route-opacity frequently appear together in the diversion patterns that regulators describe in their published guidance.

The fourth is a counterparty that resists providing the standard representations and warranties described in Step 4, or that proposes to negotiate their scope significantly downward. A commercially rational party with nothing to hide does not typically object to a straightforward AIS and insurance verification clause.

The fifth is a transfer location in, or transiting through, a geography subject to area-wide controls or heightened enforcement attention. Port-access restrictions and geographic-scope provisions in the applicable regimes operate independently of cargo-level prohibitions; a transfer route may be restricted even where the specific cargo is not.

Where more than two of these indicators are present simultaneously, in our experience the correct step is to pause the fixture and seek legal review before proceeding. Proceeding with known unresolved indicators and documenting them as noted exceptions is the pattern of conduct most likely to be characterised as reckless – rather than inadvertent – by an enforcement authority.

This publication is general information and does not constitute legal advice. For advice on your situation, contact info@caldervance.com.