Safe ship-to-ship cargo transfers require careful planning, compatible vessels and continuous monitoring of operational risks, according to guidance highlighted by West P&I.
The safety considerations involved in ship-to-ship (STS) transfers involving bulk carriers. Drawing on INTERCARGO’s Ship to Ship Transfer Guidelines for Bulk Carriers, she highlights practical measures for reducing risks during cargo operations between vessels, barges, trans loaders and floating transfer facilities.
STS operations are commonly used where draft restrictions, limited port infrastructure or unsuitable berths prevent conventional cargo handling. However, operating two vessels alongside each other introduces additional risks associated with vessel movement, mooring arrangements, cargo equipment and environmental conditions.
According to MacCarthy, the planning process should begin with an assessment of the transfer location, including water depth, under-keel clearance, weather conditions, currents, vessel traffic and the availability of emergency assistance.
Vessel compatibility is another important consideration. Even when two ships are individually suitable for STS operations, differences in their dimensions, freeboard, hull configuration and cargo-handling arrangements may create risks when they operate alongside each other.
West P&I also emphasizes the importance of defining environmental operating limits before the transfer begins. Wind, waves, swell and currents can affect vessel movements and increase the loads acting on mooring lines and fenders.
These limits should be reflected in a specific STS plan, together with clear criteria for suspending cargo operations or separating the vessels if conditions become unsafe.
Key safety recommendations
Based on the guidance West P&I highlights several measures for safer STS operations:
- Assess vessel compatibility: Evaluate vessel dimensions, draft, freeboard, hull configuration, cargo equipment and mooring arrangements before commencing operations.
- Establish operating limits: Define acceptable weather and environmental conditions, together with criteria for suspending or terminating the transfer.
- Inspect mooring and fendering arrangements: Verify that equipment is suitable and properly maintained, and continuously monitor line tension, chafing, fender positions and vessel movement.
- Maintain vessel stability: Monitor cargo distribution, ballast operations, draft, trim and list, while ensuring shear forces and bending moments remain within permissible limits.
- Control cargo-handling equipment: Establish agreed transfer rates and operating restrictions to prevent contact between cranes, grabs, conveyors and vessel structures.
- Ensure adequate crew preparedness: Confirm that sufficient rested personnel are available and that responsibilities, emergency procedures and communication arrangements are clearly understood.
- Prepare for emergencies: Agree on primary and backup communication methods, emergency signals and arrangements for stopping operations or separating the vessels.
Human factors and continuous monitoring
Beyond the technical considerations, West P&I draws attention to the additional workload STS operations can place on Masters and crews.
Personnel may be required to manage navigation, anchoring, mooring, cargo handling and emergency readiness simultaneously. Ensuring sufficient rest, clear responsibilities and effective communication between vessels is therefore essential.
The Club also stresses that safety monitoring must continue throughout the transfer. Changes in draft, freeboard, cargo distribution or environmental conditions can affect the suitability of the original mooring and cargo-handling arrangements.
INTERCARGO’s guidance includes practical checklists covering vessel compatibility, pre-transfer preparations, mooring, cargo operations, unmooring and the assessment of STS service providers.
The operators shall to incorporate these tools into their existing safety management procedures and vessel-specific risk assessments, rather than relying on them solely as reference material.