Panama MMC-217 – Ship-to-Ship (STS) Transfer Operations and Flag Notification
Panama Maritime Authority – Merchant Marine Circular MMC-217
Issue: October 2026
Subject: Ship-to-Ship (STS) transfer operations and flag notification.
Panama has established requirements for Panamanian-flagged oil tankers of 150 gross tonnage and above engaged in ship-to-ship oil cargo transfer operations. The circular addresses STS Operations Plans, prior notification to the Flag State, supporting vessel records, operational reporting and enforcement measures intended to strengthen safety, pollution prevention and controls against operations involving sanctioned vessels.
Purpose and Regulatory Background
Merchant Marine Circular MMC-217 informs owners and operators of Panamanian-flagged oil tankers about the requirements governing Ship-to-Ship (STS) operations, particularly the notification of the Panama Maritime Authority when oil cargo transfers take place between tankers.
Panama adopted the amendments to MARPOL Annex I introduced by IMO Resolution MEPC.186(59), which added Chapter 8 concerning the prevention of pollution during the transshipment of oil cargoes between tankers at sea.
The circular also refers to IMO Resolution A.1192(33), adopted on 6 December 2023, which urges Member States to promote measures against illegal operations by the Dark Fleet or Shadow Fleet. This resolution is cited by the circular as a recommendation.
Panama subsequently introduced additional STS notification requirements through Resolution No. 106-035-DGMM of 11 April 2025.
Applicability of the STS Notification Requirements
Who is covered?
All Panamanian-flagged oil tankers of 150 gross tonnage and above engaged in the transfer of oil cargo between oil tankers, wherever the vessels are located, including within the jurisdictional waters of other countries.
The notification requirements apply to both vessels participating in the operation: the discharging tanker and the receiving tanker.
Operations excluded from the STS notification requirement
Bunkering operations: Bunkering is excluded from the STS notification provisions described in the circular.
Operations in Panama waters: STS operations within Panama's territorial sea or exclusive economic zone must follow Resolution J.D. No. 038-2022 of 25 August 2022.
Offshore platforms and units: Oil transfers associated with fixed or floating platforms, including drilling rigs, FPSOs used for offshore oil production and storage, and FSUs used for offshore storage of produced oil, are excluded.
Safety and pollution response: STS operations necessary for ship safety, saving lives at sea or combating specific pollution incidents to minimize pollution damage are excluded.
Government non-commercial vessels: Operations involving a warship, naval auxiliary or other State-owned or operated vessel used exclusively for government non-commercial service are excluded.
Fishing vessels: Fishing vessels and vessels engaged in fishing-related activities are excluded.
STS Operations Plan Requirements
Any oil tanker subject to MARPOL Annex I, Chapter 8 and involved in STS operations must carry an STS Operations Plan prescribing how the operation is to be conducted.
The plan must take account of IMO convention requirements relating to safety and pollution prevention and the relevant IMO and industry guidance identified in MMC-217.
Applicable guidance
The circular identifies the IMO Manual on Oil Pollution, Section I – Prevention, as amended, and the ICS and OCIMF Ship to Ship Transfer Guide for Petroleum, Chemicals and Liquefied Gases (2025).
Language requirements
The STS Operations Plan must be written in English and in the working language of the ship.
Operational compliance
STS operations must be conducted in accordance with the approved STS Operations Plan.
Flag State notification
The plan must include procedures for notifying the Panama Maritime Authority when and where STS operations will take place, particularly during mid-ocean transfers.
All ship operator companies of Panamanian-flagged oil tankers of 150 GT and above must update their STS Operations Plans to include the Flag State notification requirement and contact their Recognized Organizations for approval of the updated plans.
Records of oil cargo transfer operations required in the Oil Record Book and Emissions Part II – Cargo and Ballast Operations Book, together with other records required by the STS Operations Plan, must be retained on board for three years.
Approval and Review by Recognized Organizations
Recognized Organizations authorized by the Republic of Panama are responsible for approving STS Operations Plans on behalf of the Administration.
Review deadline specified in MMC-217
Updated STS Operations Plans must be reviewed by an authorized Recognized Organization no later than the first annual, intermediate or renewal survey of the International Oil Pollution Prevention Certificate (IOPP), whichever occurs first, after 6 August 2025.
The review is intended to verify that the information required under paragraph 6.6 of MMC-217 has been included in the plan.
Recognized Organizations seeking authorization or delegation of authority to approve STS Operations Plans are instructed to contact the Panama Administration at:
Mandatory STS Notification – Mid-Ocean Operations
Effective date: 6 August 2025
All Panamanian-flagged oil tankers acting as discharging and/or receiving vessels must notify the Panama Flag State of their STS cargo transfer operations through the E-Segumar platform at least 48 hours before the scheduled date and time of the intended operation.
Notifications must be submitted through the official E-Segumar platform:
Panama E-Segumar – Certificates Platform
Where an STS operation involves two Panamanian-flagged oil tankers, both vessels must submit notification to the Panama Flag State through E-Segumar.
Information required in the notification
Vessel identification: Name, flag, call sign, IMO Number and estimated time of arrival of each oil tanker involved in the STS transfer.
Planned operation details: Date, time and geographical position where the STS transfer is scheduled to commence.
Transfer method: Confirmation whether the STS operation will be conducted at anchor or underway.
Cargo information: Type and quantity of oil to be transferred.
Operation duration: Expected duration of the STS transfer operation.
DPA details: Identification and contact information, including email address and telephone number, of the Designated Person Ashore for each tanker.
STS Plan confirmation: Confirmation that the tanker carries an STS Operations Plan complying with Regulation 41 of MARPOL Annex I.
Supporting Documents and Onboard Records
At the time of STS notification, Panamanian-flagged oil tankers must maintain valid and updated copies of the following documents on board:
Continuous Synopsis Record (CSR)
The vessel must maintain a valid and updated Continuous Synopsis Record at the time the STS operation is notified.
Conformance Test Report (CTR)
The vessel must also maintain a valid and updated Conformance Test Report on board.
Failure to comply with these documentary requirements will result in denial of authorization for the STS operation until compliance has been demonstrated.
The acknowledgement of receipt issued by the Flag State through E-Segumar must be retained on board electronically for a minimum period of three years.
Changes to the Planned Operation and Cancellation
If the estimated time of arrival of an oil tanker at the STS transfer location or area changes by more than six hours, or if the STS operation is cancelled for any reason, the Master, Owner or Designated Person Ashore must immediately inform the Panama Maritime Authority.
Required notification email
The notification must be sent immediately when the relevant change or cancellation becomes known.
Failure to provide timely notification may lead to administrative measures under the applicable maritime regulations and the Administration's oversight procedures.
Enforcement, AIS and LRIT Compliance
MMC-217 requires Panamanian-flagged oil tankers of 150 GT and above to comply with the applicable Panama national legislation and the provisions concerning LRIT and AIS referenced in the circular.
AIS and LRIT operation
When engaged in STS transfer operations, AIS and LRIT must be working properly in accordance with the applicable requirements.
Sanctioned vessels
Panamanian-flagged oil tankers of 150 GT and above are prohibited from engaging in STS transfer operations with vessels included in international sanction lists recognized by the Panamanian State.
Administrative sanctions
Vessels failing to comply with Panama's national legislation may be subject to sanctions, including cancellation of registry, depending on the seriousness of the circumstances.
Prohibition on support
Panamanian-flagged vessels are strictly prohibited from providing, facilitating or participating, directly or indirectly, in any form of support to sanctioned vessels, in accordance with Executive Decree No. 512 of 18 October 2024.
Responsibilities of Shipowners, Operators and Masters
The requirements of MMC-217 place practical responsibilities on the vessel's operating company and the personnel responsible for planning and conducting STS transfers.
Shipowners and operators: Ensure that applicable tankers carry an approved and updated STS Operations Plan, and that the Flag State notification procedure is incorporated into the plan.
Masters: Ensure that STS operations are conducted in accordance with the approved plan and that changes or cancellations are reported as required.
Designated Persons Ashore: Support the notification process, provide the required contact information and ensure that significant changes to the planned operation are communicated to the Administration.
Recognized Organizations: Approve the STS Operations Plan and verify that the required Flag State notification information has been incorporated during the applicable IOPP survey review.
Key Compliance Considerations
Owners and operators of Panamanian-flagged oil tankers should verify the following before arranging an STS oil cargo transfer:
- Confirm whether the vessel falls within the circular's applicability threshold and scope.
- Ensure that the STS Operations Plan is updated and approved by an authorized Recognized Organization.
- Verify that the plan incorporates the Flag State notification procedure.
- Submit the E-Segumar notification at least 48 hours before the planned operation.
- Where both vessels are Panama-flagged, ensure that both submit their notifications.
- Verify that the CSR and CTR are valid and updated.
- Retain the Flag State acknowledgement electronically on board for at least three years.
- Ensure that the required cargo-transfer records are retained on board for three years.
- Maintain proper AIS and LRIT operation during the STS operation.
- Verify that the other vessel is not subject to applicable international sanctions recognized by Panama.
- Immediately notify the Administration if the ETA changes by more than six hours or the operation is cancelled.
Frequently Asked Questions – Panama MMC-217
Which vessels are subject to Panama MMC-217?
The circular applies to Panamanian-flagged oil tankers of 150 gross tonnage and above engaged in oil cargo transfers between tankers, wherever they are located, including within the jurisdictional waters of other countries.
Does the STS notification requirement apply to both vessels?
Yes. Panamanian-flagged oil tankers acting as discharging and/or receiving vessels must notify the Flag State. If both vessels involved are Panamanian-flagged, both must submit notification through E-Segumar.
How far in advance must an STS operation be notified?
The notification must be submitted at least 48 hours before the scheduled date and time of the intended STS operation.
Where must the STS notification be submitted?
Notification must be submitted through the Panama Maritime Authority's E-Segumar platform at certificates.amp.gob.pa/certificates.
Is an approved STS Operations Plan required?
Yes. An oil tanker subject to MARPOL Annex I, Chapter 8 and involved in STS operations must carry an STS Operations Plan. The plan must be approved by a Recognized Organization authorized by Panama.
Which guidance should be considered when preparing the STS Operations Plan?
The circular identifies the IMO Manual on Oil Pollution, Section I – Prevention, as amended, and the ICS and OCIMF Ship to Ship Transfer Guide for Petroleum, Chemicals and Liquefied Gases (2025).
What language must be used in the STS Operations Plan?
The plan must be written in English and in the working language of the ship.
Which documents must be valid and updated at the time of notification?
The tanker must maintain a valid and updated Continuous Synopsis Record (CSR) and Conformance Test Report (CTR) on board. Failure to meet these requirements may result in denial of authorization for the STS operation until compliance is demonstrated.
How long must STS records be retained on board?
Oil cargo transfer records required in the Oil Record Book and Emissions Part II – Cargo and Ballast Operations Book, together with other records required by the STS Operations Plan, must be retained for three years. The E-Segumar acknowledgement must also be retained electronically on board for at least three years.
What happens if the vessel's ETA changes by more than six hours?
The Master, Owner or Designated Person Ashore must immediately inform the Panama Maritime Authority by email at [email protected]. The same immediate notification requirement applies if the STS operation is cancelled.
Are bunkering operations covered by the STS notification requirement?
No. MMC-217 expressly excludes bunkering operations from the STS notification requirement described in the circular.
Do STS operations involving FPSOs and FSUs fall within this notification requirement?
No. Oil transfer operations associated with fixed or floating platforms, including FPSOs used for offshore production and storage of oil and FSUs used for offshore storage of produced oil, are listed among the exclusions in paragraph 3.2.
Can a Panamanian tanker conduct an STS operation with a sanctioned vessel?
No. MMC-217 prohibits Panamanian-flagged oil tankers of 150 GT and above from engaging in STS transfers with vessels included in international sanction lists recognized by the Panamanian State. It also prohibits direct or indirect support to sanctioned vessels.
What are the possible consequences of non-compliance?
Failure to provide timely notification may lead to administrative measures. Non-compliance with Panama's national legislation may result in sanctions, including cancellation of registry, depending on the seriousness of the circumstances.
Regulatory References and Official Contact
MMC-217 refers to the following regulatory instruments:
- Law No. 17 of 9 November 1981 and Protocol Law No. 1 of 25 October 1983 – MARPOL 73/78.
- Executive Decree No. 512 of 18 October 2024.
- Resolution J.D. No. 038-2022 of 25 August 2022.
- Resolution No. 106-OMI-087-DGMM of 22 November 2010, adopting IMO Resolution MEPC.186(59).
- Resolution No. 106-048-DGMM of 19 August 2019, as stated in the circular's reference list.
- Resolution No. 106-035-DGMM of 11 April 2025.
- IMO Resolution A.1192(33) of 6 December 2023, cited as a recommendation.
Panama Maritime Authority – Official Contact
Fleet Control and Monitoring Section
Maritime Ship Security Department
General Directorate of Merchant Marine
Panama Maritime Authority
Telephone: +507 501-4223 / 5351
Email: [email protected] / [email protected]
Official circulars: Panama Maritime Authority – Merchant Marine Circulars
E-Segumar: E-Segumar Certificates Platform
Circular revision history:
- October 2026 – Modification in paragraph 6.2.
- January 2026 – Paragraph 4.2 amended to include the OCIMF Ship to Ship Transfer Guide for Petroleum, Chemicals and Liquefied Gases (2nd Edition 2025); new paragraph 7.4.
- August 2025 – Paragraphs 4.2 and 6.2 amended.
- July 2025 – Restructuring of the circular.
- November 2023 – Reference and scope of paragraph 2 revised.
- July 2002 – Earlier circular issue.