Checklist for Ship to Ship Transfer or STS Operation
Introduction
In the world of seafaring, Ship to Ship (STS) transfer operations are a common yet critical procedure. Whether it’s loading or discharging cargo like crude oil, LNG, or other bulk liquids, STS operations require meticulous coordination and planning. One small mistake can lead to serious safety risks, environmental damage, or operational delays.
As a professional mariner, I’ve seen firsthand how smooth STS transfers can be when proper procedures and checklists are followed. In this post, we’ll break down the STS procedure checklist, explain why it’s essential, and discuss the who, what, when and how of a successful ship-to-ship operation. Whether you’re a deck cadet or a seasoned Chief Officer, this guide can help you better understand and prepare for any STS transfer.
What is a Ship to Ship (STS) Transfer?
A Ship to Ship (STS) transfer operation is the process of transferring cargo, typically liquid cargo, between two ships positioned alongside each other at sea or in port. These operations are commonly carried out for efficiency, commercial or logistical reasons, or sometimes due to port restrictions.
STS operations are particularly critical for:
- Crude oil and product tankers
- LNG/LPG carriers
- Bulk liquid cargo ships
Why STS Operations Require a Checklist
STS operations involve multiple risks—ranging from vessel collision to pollution and spillage. Because of this, it’s essential to follow a thorough Ship to Ship transfer checklist to ensure:
- Safety of the crew and vessel
- Compliance with international regulations (such as MARPOL and SOLAS)
- Environmental protection—especially in sensitive marine areas
- Efficient and error-free operations
Using approved checklists ensures that every box is ticked before the operation begins, reducing the chance of human error or oversight.
Who is Involved in STS Operations?
Performing a ship-to-ship transfer is not a solo effort—it involves coordination between multiple parties. Here’s who typically plays a role:
- Master of each vessel – Has ultimate authority onboard, responsible for safety and compliance
- STS Superintendent or Mooring Master – Assists with maneuvering and mooring coordination
- Cargo Officers – Oversee product transfer and maintain communication
- Deck Crew – Handle fenders, mooring lines, and hoses
- Port Authorities or Charterers – Sometimes involved in planning or approval of STS operation
When and Where are STS Transfers Done?
STS operations can be carried out:
- At Anchorage – Usually in designated STS zones
- At Sea – In calm weather conditions and sheltered waters
- At Port – When terminal facilities are unavailable or not suitable
The decision on timing and location depends on multiple factors including weather, sea conditions, vessel draft, and safety considerations.
How Does an STS Operation Typically Happen?
Every STS transfer follows a structured process. Below is a simplified breakdown of how it usually unfolds—and what the STS procedures checklist covers at each stage.
1. Pre-Operation Planning
Before vessels even come close to each other, detailed planning takes place. This includes:
- Exchange of pre-arrival information between vessels (size, draft, freeboard, fender requirements)
- Weather and sea condition assessment
- Communication channels and signals to be used
- Emergency procedures agreement
- Completion of Pre-STS checklist (as per ICS and OCIMF guidelines)
Pro tip, always refer to the IMO STS Transfer Guidelines for internationally accepted best practices.
2. Pre-Transfer Operations
Once both vessels are in position:
- Vessel approach and mooring is done under the supervision of the Mooring Master
- Fenders are deployed to avoid damage from vessel contact
- Hoses and manifold connections are tested for leaks
- Ship-to-ship checklists reviewed and cross-verified
It’s crucial that both vessels perform the OCIMF STS Checklist Parts A & B before starting any cargo movement. This ensures that all systems are GO and that the crew is ready.
3. During Cargo Transfer
This is where real-time alertness is crucial. During cargo movement:
- Constant communication is maintained between Cargo Control Rooms (CCR)
- Pressure and flow rates are monitored continuously
- Tank levels are tracked to prevent overfilling or imbalance
- Emergency stop mechanisms must be ready and known to operators
- Drip trays, sorbent pads, spill kits are kept on standby
My tip as a seafarer: Always keep an eye on weather updates. Sudden wind changes can make moored ships unstable—potentially jeopardizing the whole operation.
4. Post-Transfer Operations
Once transfer is complete:
- Hoses are cleared, drained and blanked
- Tank soundings and ullage reports are finalized
- Final inspection of moorings and fenders
- Clearing the area of any leaks or spills
- Completion of OCIMF Checklist Part C
Finally, both vessels must fill out the STS Operation Report and forward it to relevant parties, including company DPA and shore authorities (if required).
Key Items in a Ship to Ship Transfer Checklist
To make it easier, here’s a quick itemized summary of what you can expect in a standard STS checklist:
- Pre-check communication protocols
- SIGTTO/ICS STS checklists A, B, and C completed
- Fender and mooring equipment readiness
- Fire-fighting and emergency systems tested and ready
- Navigation and anchoring gear in proper condition
- Crew briefing and role assignment
- Product compatibility and transfer plan recorded
- Emergency disconnect procedures clearly known
Takeaway: Safe STS Operations Start with the Right Checklist
Ship to Ship transfer is both an art and a science. While seasoned mariners might perform these tasks regularly, no operation should go ahead without a comprehensive STS operation checklist. Not only does it safeguard your vessel and cargo, but it also ensures the safety of your crew, marine life, and the environment.
So next time you’re preparing for an STS operation, remember: checklists aren’t just paperwork—they’re lifelines. Stick to the plan, communicate clearly, and always prioritize safety.
Safe watch and smooth sailing!
References:
Leave a Reply