Rolls-Royce is incorporating design features specifically aimed at ice-class vessels into its new generation of stabiliser systems, while Sweden-based Humphree has a range of interceptors and fins suited to smaller vessels
The benefits of Rolls-Royce’s Stabilisation-at-Rest (SAR) concept will soon be available to ice-class ships via its Aquarius and Neptune stabilisation systems.
Using active fin-control technology and advanced hydrodynamic design, the SAR system delivers high levels of roll reduction when vessels are at rest and can also maintain stabilisation performance when vessels are under way.
The new design is especially suitable for ice-class vessels as it allows stabiliser fins to be fully retracted into a custom-designed fin box, meaning there are no protrusions from the hullform and therefore safe ice navigation can be undertaken. It also features reduced fin area and lower fin angle to meet stabilisation performance requirements. Dynamic drag is reduced when fins are deployed under way, resulting in lower fuel costs. The stabiliser fin also incorporates Rolls-Royce’s trailing edge design, which eliminates vibration and noise.
The SAR system is incorporated into two series of Roll-Royce retractable stabilisers: the Aquarius range of stabilisers and the Neptune range.
Rolls-Royce Motion Control Dunfermline’s managing director Martin Cunningham said: “The one-piece fin construction offers simple maintenance, reducing through-life cost. The fin shape is designed to improve zero speed performance, as more chord is behind the fin centreline. This is achieved because the ice-class SAR system is based on the well-established Rolls-Royce Aquarius and Neptune retractable stabilisers. Both initial and operational costs are minimised due to the units being easily installed, the fin box custom-designed to exactly match the ship’s hull profile, small hull openings and a simple, reliable design.”
As vessels fitted with ice-class SAR stabilisers are likely to operate in environmentally-sensitive areas, this has also been incorporated into the design. A special quad-seal arrangement minimises the risk of leakage, and the machinery is compatible with many environmentally acceptable lubricants (EALs).
Mr Cunningham said: “The sealing arrangement and compatibility with EALs mean the ice-class SAR systems meet the requirements for VGP Permit vessels, while the low drag results in less fuel being burned, which also benefits the environment.”
Humphree launches new stabilisation fin
The all-speed stabilisation fin can be operated off batteries, reducing noise, fuel consumption and wear (credit: Humphree)
Gothenburg, Sweden-based Humphree produces interceptors and fins suited to smaller vessels, such as crew transfer craft and workboats.
Humphree recently introduced a new all-speed stabilisation fin that offers a number of benefits over previously available products. The main engine alternators which charge the batteries powering the 24V DC fin can be operated without the need to keep a genset engine running while under way. This results in reduced noise, fuel consumption and wear.
The fin provides up to 75% stabilisation at zero-speed and up to 85% stabilisation at speed. It is a compact system that can be installed both in retrofits and on new builds thanks to its compact servo actuators and 24V power; this means there is no need for hydraulic pumps or AC power modules that would require additional space. The patented servo actuators have a depth of just 310 mm from the exterior mounting flange and the system is typically 25%-50% lighter than existing products, said the company.
It can combat anchor walking by rotating 180 degrees when the anchor is at the bow, which means instead of pushing against the anchor it gently pulls. Humphree’s Coordinated Turn feature automatically coordinates the fins and rudder position to provide better performance during turns.
The system can be fully integrated with Humphree’s Interceptor stabilisers, allowing for roll, pitch and yaw motions to be controlled by a single system.