What is the ship to ship operation plan?

Introduction

A Ship-to-Ship (STS) operation plan defines how two vessels transfer cargo safely while at sea or anchorage. It explains procedures, assigns responsibilities, and sets safety measures. Tankers rely on it to avoid accidents and protect the marine environment. Without a clear plan, crews face higher risks of collision, pollution, and costly delays.

Regulations and Industry References

The International Maritime Organization (IMO) requires every oil tanker engaged in STS transfers to keep an approved plan under MARPOL Annex I. In addition, industry bodies such as OCIMF, ICS, and SIGTTO publish detailed guidelines. These documents provide practical advice that helps companies comply with law and adopt proven best practices. Therefore, the STS plan connects legal obligations with day-to-day operations.

Objectives and Safety Principles

The STS plan aims to:

• Protect human life on both vessels
• Prevent pollution and environmental harm
• Secure assets and maintain smooth operations
• Establish clear communication and authority lines

Because of these objectives, every officer and crew member can act with confidence and consistency.

Key Elements of an STS Operation Plan

A comprehensive plan usually covers:

1. Vessel and Cargo Information – Ship names, IMO numbers, cargo types, manifold data, and ballast conditions.
2. Location and Timing – Position, weather limits, tidal windows, and operation schedule.
3. Cargo Transfer Procedures – Pumping rates, hose specifications, and connection steps.
4. Mooring and Fendering – Type, size, and placement of fenders plus mooring line distribution.
5. Ship Compatibility – Stability impact, manifold alignment, and safety margins.
6. Communication Protocols – VHF channels, reporting chain, and Person in Overall Advisory Control (POAC).
7. Environmental Conditions – Wind, wave, current, and visibility thresholds.
8. Checklists and Permits – Pre-transfer meeting notes, safety permits, and authority approvals.
9. Emergency and Abort Procedures – Disconnection sequence, separation plan, and oil spill measures.
10. Record Keeping – Transfer logs, event reports, and compliance documentation.

In short, these elements ensure the operation runs smoothly and safely from start to finish.

Pre-Operation Preparations

Before transfer begins, both vessels hold a Pre-Transfer Meeting (PTM). During this meeting, crews review compatibility, confirm communication procedures, and complete safety checklists. They also test equipment, notify authorities, and assign clear roles. As a result, everyone understands the plan and knows how to respond.

Operational Procedures

During the transfer, mooring masters guide the approach. The ships align carefully under favorable conditions. After securing mooring lines and placing fenders, the crews connect hoses and perform pressure tests. Pumping starts slowly, and officers increase the rate step by step. Meanwhile, both vessels monitor manifold pressure, tank levels, and weather changes. Moreover, they exchange updates regularly over the agreed channel to maintain coordination.

Monitoring, Records, and Reporting

Officers log every step, including start times, pump speeds, and cargo quantities. If an incident occurs, they report it immediately to company offices, maritime authorities, and classification societies. Good records not only prove compliance but also help companies improve future operations.

Abort and Emergency Procedures

The STS plan lists clear abort criteria. If wind, waves, or visibility exceed the safe limit, the crews stop pumping and prepare for disconnection. They follow a defined sequence to release hoses, let go mooring lines, and separate safely. In addition, oil spill response teams stand ready with booms and clean-up gear.

Equipment and Checklists

Every STS transfer requires reliable equipment. Crews check hoses, emergency towing arrangements, fire-fighting systems, and communication tools. Structured checklists guarantee that officers review each item before, during, and after transfer. In this way, no critical detail gets overlooked.

Personnel Training

The competence of the crew makes the biggest difference in STS safety. Masters, officers, and deck teams train regularly with industry guidelines. The POAC supervises the process and ensures both ships follow the same rules. Frequent drills and refresher training strengthen their readiness.

Environmental and Pollution Prevention

Protecting the sea remains a central duty of every STS plan. Crews prepare spill booms, drip trays, and clean-up kits before transfer. If an oil spill happens, they deploy the gear immediately and notify local authorities. In addition, the plan requires proactive checks such as hull integrity and tank tightness to prevent leaks before they occur.

Conclusion

The ship-to-ship operation plan functions as a complete safety framework. It brings together regulations, procedures, and emergency actions into one clear guide. By following it, crews protect people, cargo, and the marine environment. Furthermore, companies benefit from fewer incidents, lower costs, and stronger compliance.

FAQ

1. Who approves an STS operation plan?
The vessel’s flag state or a recognized classification society approves the plan.

2. Do ships need a plan for every transfer?
Yes. Tankers carrying petroleum, chemicals, or gas must use a valid plan for each operation.

3. What does the POAC do?
The Person in Overall Advisory Control coordinates the transfer, manages communication, and checks compliance.

4. Can ships transfer cargo in rough weather?
No. If conditions exceed safe thresholds, the transfer must stop immediately.

5. How often should companies update the plan?
They should review it at least once a year or whenever regulations or ship conditions change.