Ship-to-Ship Transfer: The Floating Port You Already Have
How transferring cargo between vessels at sea can cut port fees, save time, and open routes that fixed terminals close off.
Not every cargo movement has to pass through a quay. Ship-to-ship transfer, or STS, is the practice of moving cargo directly from one vessel to another while both are afloat, either at anchor in a sheltered area or, in some cases, underway. It turns open water into a working interface, and for the right shipment it can be the difference between a clean, predictable delivery and a slow crawl through congested infrastructure.
What actually happens during an STS operation
Two vessels are brought alongside each other and held in position with fenders between their hulls to absorb contact and protect the plating. Mooring lines connect them, transfer equipment is rigged, and cargo moves across. The whole sequence is governed by a documented plan agreed in advance: who approaches whom, in what weather window, at what speed, with what contingency if conditions shift. Done properly, it is a controlled, rehearsed procedure rather than an improvisation, and the planning is where most of the value and most of the safety lives.
When it makes commercial sense
STS earns its place in a few recurring situations. The first is draft. When a receiving port is too shallow for a fully laden vessel, cargo can be lightered onto smaller craft offshore so the larger ship can enter, or so the cargo can reach a berth the deep-draft ship could never use. The second is reach. Some destinations simply have no terminal capable of handling a given parcel, and an at-sea transfer onto a self-discharging or shallow-draft vessel bridges that last gap. The third is timing. When berths are booked solid and demurrage is mounting, transferring cargo at anchor can keep a shipment moving instead of waiting in line.
What it saves a shipper
The savings are usually a mix of three things. Port fees and berth charges fall away or shrink, because the transfer happens outside the terminal's fee structure. Time is recovered, since you are not held hostage to a single berth's schedule. And flexibility goes up: you can serve a buyer whose harbour was previously off-limits, or split a large parcel across multiple smaller deliveries without re-routing the whole voyage. For shippers working into Europe's mix of major hubs and smaller regional ports, that flexibility is often the headline benefit.
The part that is easy to underestimate
STS is not a shortcut around discipline. It demands compatible vessels, properly maintained fendering and transfer gear, experienced crews on both sides, and a weather judgment that errs toward caution. The operators who do it well treat each transfer as a standalone project with its own plan and its own go or no-go criteria. That is precisely why it suits a carrier that has been running customized transfers for years rather than one improvising for the first time.
The takeaway
Think of STS less as an exotic option and more as a tool: when geography, draft, or congestion stands between your cargo and its buyer, a well-run transfer at sea can be the most direct route you have. The question to ask a carrier is not whether they can do it, but how they plan it. Raduga has built customized ship-to-ship transshipment into its core service precisely because so many real-world routes need it.