Liquid Replenishment at Sea Systems (RAS-L)
Van Halteren Technologies designs, supplies and supports integrated Liquid Replenishment at Sea (RAS-L) systems for transferring marine fuel, aviation fuel, water and other specified fluids while vessels remain underway. The modular scope covers abeam and astern arrangements, transfer and receiving stations, hoses, winches, tensioning, pressure control, monitoring, controls and vessel integration.
For new-build and in-service naval vessels, Van Halteren Technologies supports the process from feasibility and interface engineering through system delivery, commissioning, training and lifecycle support. Electric, hydraulic and hybrid drive configurations are available, allowing each RAS-L system to be configured around the platform architecture, operating concept and available space, weight and power.
What is liquid replenishment at sea?
Liquid Replenishment at Sea (RAS-L), also known as Fueling at Sea (FAS) and part of Connected Replenishment (CONREP) or Underway Replenishment (UNREP), enables naval vessels to receive fuel and fluids without returning to port. During an abeam operation, the supplying and receiving vessels sail alongside each other while dedicated hoses, transfer rigs and tensioned handling equipment maintain a controlled ship-to-ship connection.
Systems can be engineered around the operating navy’s replenishment procedures and customer-specified naval publications, including ATP-16 requirements.
By replenishing at sea, fleets can remain operational for extended periods without returning to port, enabling task groups to sustain missions, maintain a continuous presence, and extend operational reach wherever required
Supporting sustained Naval operations
As naval vessels become larger, more complex and increasingly dependent on sustained deployment, reliable replenishment capability remains a key enabler of fleet operations. Modern RAS-L systems are therefore designed to combine high transfer performance, operational simplicity and long-term reliability, ensuring that fueling operations can be conducted safely and efficiently throughout the vessel’s service life.
Integrated RAS-L system scope
At Van Halteren Technologies RAS-L solution is engineered as an integrated transfer chain rather than a set of stand-alone components. The system scope typically covers transfer hoses, hose-handling and replenishment rigs, winches, tensioning equipment, pressure-control equipment, control and monitoring systems, receiving-station components .
This integrated approach helps shipyards, naval architects, system integrators and operators coordinate mechanical, hydraulic, electrical and control requirements from an early project stage.
Liquid Replenishment at Sea via the Astern method
Van Halteren Technologies also designs and supports Replenishment at Sea Astern systems for fuel transfer to a receiving vessel positioned behind the supplying ship. An astern arrangement is a valuable option where alongside replenishment is not available, not preferred or not aligned with vessel design, mission requirements or operating doctrine.
The system is configured around vessel interfaces, hose handling, controlled tension, deployment and recovery, monitoring and the required operational envelope.
RAS receiving stations for liquid transfer
Van Halteren Technologies supplies RAS receiving stations and associated equipment for the reception of ship fuel, aviation fuel, water and other customer-specified fluids. Engineering support covers integration into new-build and retrofit projects for frigates, corvettes, offshore patrol vessels, multipurpose vessels and landing platform docks.
Receiving-system design is coordinated with deck space, routing, structural interfaces, controls, maintainability and the operating navy’s procedures.
Compact integration, drive options and lifecycle support
RAS-L solutions can be delivered with electric, hydraulic or hybrid drives to match vessel utilities, space, weight and power constraints. Compact, integration-focused equipment arrangements help preserve valuable space for other mission systems while supporting safe operation and maintainability.
Van Halteren Technologies also supports the system throughout its lifecycle with documentation, training, spare parts, maintenance, upgrades and assistance for in-service vessels.
Innovation-Driven Naval Replenishment Technology
At Van Halteren Technologies (VHT), innovation is at the core of our Replenishment at Sea (RAS) solutions. We continuously develop new technologies to enhance ease of operation, maximize safety, and reduce environmental impact. Designed to meet the highest naval standards, our RAS systems combine exceptional performance and reliability with a compact, integration-friendly design, minimizing footprint, weight, and power consumption while preserving valuable space for other mission-critical ship systems.
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FAQ
Learn about liquid replenishment at sea.
What does Van Halteren Technologies supply for a Liquid Replenishment at Sea system?
At Van Halteren Technologies RAS-L solution is engineered as an integrated transfer chain rather than a set of stand-alone components. The system scope typically covers transfer hoses, hose-handling and replenishment rigs, winches, tensioning equipment, pressure-control equipment, control and monitoring systems, receiving-station components
Can Van Halteren Technologies integrate RAS-L into an existing naval vessel?
Yes. Van Halteren Technologies supports feasibility and interface studies for in-service vessels and develops configurations around the available deck arrangement, utilities, structural interfaces and operating requirements.
What is the difference between RAS-L, FAS, CONREP and UNREP?
RAS-L describes liquid transfer at sea. FAS refers specifically to fueling at sea. CONREP describes connected replenishment between vessels, while UNREP is the broader term for replenishment conducted while vessels remain underway.
What is the difference between RAS-L and RAS-S?
RAS-L (Replenishment at Sea – Liquids) is used to transfer liquids such as fuel between ships while underway, using hose bundles suspended by trolleys on a span wire. RAS-S (Replenishment at Sea – Solids) is used to transfer solid cargo, supplies, or equipment, with the payload carried between ships on a high-line traveler system.
What is the best method for the drive of the winches: electric or hydraulic?
At Van Halteren, we do not have a preference for a specific winch drive method. We work according to our customers’ requirements and operational needs. Both drive concepts offer their own unique advantages, and together with the customer we determine the solution that best fits their application.
Factors such as energy consumption, weight, footprint, ease of operation, maintenance requirements, and life-cycle support play an important role in this selection process. Regardless of the chosen drive method, VHT delivers a safe, reliable system that is fully supported throughout the vessel’s operational lifetime.
Discuss your Liquid Replenishment at Sea requirements
Planning a new RAS-L installation, in-service upgrade, astern system or receiving station? Van Halteren Technologies can help define the interfaces, operating requirements and most suitable system configuration.
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Our team is ready to help
Replenishment at sea systems must be reliable, safe and compatible with naval operational procedures. If you are evaluating a system for a vessel or naval project, our Sales Manager can help assess the technical requirements.
