Safer Ship-to-Ship Transfers: Practical Lessons for Bulk Carrier Operations
Ship-to-ship (STS) transfer operations are an established part of dry bulk shipping, particularly where draught restrictions, limited port infrastructure or the absence of a suitable berth make direct loading or discharge impracticable. However, bringing two vessels alongside to transfer cargo introduces risks that differ considerably from conventional terminal operations.
INTERCARGO’s Ship to Ship Transfer Guidelines for Bulk Carriers provides practical guidance specifically for the dry bulk sector, covering operations between bulk carriers as well as transfers involving barges, transloaders, floating cranes and transshipment units.
For Members undertaking STS operations, the publication provides a useful framework for answering three fundamental questions: Are the vessels and location suitable? Is the operation properly planned? And are the risks being effectively controlled throughout the transfer?
Plan before the vessels meet
Safe STS operations begin well before the vessels come alongside.
Operators should ensure that the proposed transfer location has been assessed, taking account of factors such as water depth, under-keel clearance, traffic, weather exposure, currents, security, local requirements and the availability of tugs and emergency support.
Where an STS service provider is involved, appropriate due diligence should also be undertaken to establish that the provider has suitable experience, competent personnel, appropriate equipment and effective safety and emergency procedures.
A key part of the planning process is vessel compatibility. The fact that two vessels are individually capable of conducting STS operations does not necessarily mean they are suitable for operating alongside each other.
The compatibility assessment should consider matters including:
- vessel dimensions, draught and freeboard;
- hull configuration and projecting structures;
- hatch positions and cargo gear operating envelopes;
- mooring arrangements and equipment;
- fender requirements;
- anticipated changes in freeboard during cargo transfer;
- cargo and ballast sequences; and
- tug and emergency arrangements.
These considerations should then feed into a Specific STS Plan for the operation.
Establish clear operating limits
Environmental conditions can significantly affect the interaction between two vessels alongside each other.
Wind, waves, swell, current and passing traffic can influence vessel movement, fender loads and mooring forces. Importantly, there is no single environmental limit suitable for every STS operation. Vessel size, displacement, freeboard, mooring arrangements and the degree of shelter at the transfer location all influence how the vessels will respond.
The Specific STS Plan should therefore establish clear operational limits and identify when cargo operations should be suspended or the vessels separated.
The Master should retain the authority to delay, suspend or terminate the operation where conditions are considered unsafe.
Treat fendering and mooring as critical controls
Fenders and moorings form the physical connection between the vessels and require careful planning.
Fenders should be suitable for the vessels involved and the expected operating conditions, with sufficient stand-off to prevent contact between hulls or projecting structures. Their condition, certification, pressure and deployment arrangements should be verified before use.
Similarly, the mooring arrangement should be agreed before the operation and should account for changes in draught and freeboard as cargo and ballast are transferred.
Once alongside, moorings and fenders require continuous monitoring. Changes in line leads, tension, chafing, fender position or vessel movement may indicate that the original arrangement is no longer providing the intended level of protection.
Maintain control during cargo transfer
STS planning does not end once the vessels are safely alongside.
The cargo-transfer sequence should maintain adequate stability and keep shear forces and bending moments within permissible limits throughout the operation. Ballasting, draught, trim, list and changes in freeboard should be monitored as the transfer progresses.
Cargo equipment also requires particular attention. Crane outreach, grab movement, conveyors and other equipment may operate close to hatch coamings, hatch covers or the adjacent vessel. Excessive movement can result in structural damage, cargo spillage or injury.
The cargo plan should therefore establish agreed transfer rates, cargo sequences, equipment limitations and stop-work criteria.
Do not overlook the human element
STS operations can place additional demands on Masters and crews already managing navigation, anchoring, cargo operations and routine shipboard responsibilities.
Operators should consider whether sufficient rested personnel are available for mooring, cargo watches, emergency duties and eventual unmooring. Roles, responsibilities, communication channels and emergency signals should be clearly understood before operations commence.
Effective communication between the vessels is particularly important. Primary and backup communication methods should be agreed and tested, together with a common working language.
Use the guidance as a working tool
One of the most useful aspects of INTERCARGO’s publication is its practical material.
The guidance includes checklists covering:
- vessel compatibility;
- preparations before commencing STS operations;
- preparations before mooring;
- preparations before cargo transfer;
- preparations before unmooring; and
- due diligence of STS service providers.
It also contains practical information on fender selection, mooring arrangements and cargo operations.
These tools are most valuable when incorporated into the operator’s existing safety management procedures and used during the planning and execution of individual operations, rather than simply retained on board as reference material.
A useful resource for Members
Bulk carrier STS operations bring together vessel compatibility, mooring, fendering, cargo handling, stability, environmental conditions and human factors within a single operation. Effective loss prevention therefore depends on considering these elements collectively rather than in isolation.
Members conducting, or considering, dry bulk STS operations are encouraged to consult INTERCARGO’s Ship to Ship Transfer Guidelines for Bulk Carriers and use its practical guidance, checklists and planning tools to support their own procedures and vessel-specific risk assessments.