Industry Explainers
How Offshore Ship-to-Ship Transfers Work
4 September 2026 · 5 min read
Ship-to-ship transfers move petroleum products between vessels at sea. Here is how the process works and why it matters.
A ship-to-ship (STS) transfer moves cargo, such as refined petroleum products, directly from one vessel to another, usually at anchor or underway in sheltered waters. It is a key part of offshore supply.
Why STS transfers are used
- Supplying areas where ports have limited draught or capacity
- Breaking large cargoes into smaller parcels for coastal delivery
- Reducing port congestion and turnaround times
- Supporting offshore installations and marine operations
The process, step by step
Planning comes first. The vessels, location, weather window and cargo details are assessed and agreed. The vessels then come alongside, separated by large fenders, and transfer hoses are connected under strict procedures. Product is pumped across while both crews monitor rates, pressures and quantities, and the operation ends with documentation and quantity reconciliation.
Why monitoring matters
Each step carries commercial and operational risk. Sleeklink's transaction monitoring service represents clients throughout, checking quantities, quality and documentation so the transaction closes smoothly.
