Air lubrication

Reduces the resistance of the vessels by reducing the frictional resistance on the flat bottom of the hull

The Air Lubrication System (ALS) chosen for the CHEK Project is supplied by London-based Silverstream Technologies. Silverstream’s market-leading ALS, the Silverstream® System, is a proven energy efficiency technology which fundamentally changes the interaction between water and a vessel, shearing air from air release units (ARUs) in the hull to create a carpet of microbubbles that coats the full flat bottom of a vessel.

Independent third parties including Lloyd’s Register, HSVA and the University of Southampton have verified that the Silverstream® System generates an average 5-10% net fuel and emissions saving, depending on vessel type. Silverstream’s customers include MSC, Shell, Carnival, Maersk, Grimaldi, Vale, ADNOC L&S and many others.

The Silverstream® System is unique in that it is the only proven ALS that can be retrofitted in 10 days or less, as well as being applicable for newbuildings. It lasts the lifetime of the vessel, is complementary to and can be used in conjunction with other clean technologies, as in the case of the CHEK Project, and its return on investment is typically between two and five years.

The system is applicable to all of shipping’s major segments and is effective in all sea states. It is also fuel-agnostic, meaning it is well-suited to both existing and future fuels. This gives shipowners the assurance that they are investing in a lifecycle solution for vessel efficiency.


D6.1 (Drag Reduction Technology Specification) introduces the design and placement of Silverstream Technologies’ patented air release units (ARUs). The deliverable also provides initial specification of piping, valves, electrical supply, distribution boards, machinery arrangement, ventilation, as well as the control and automation system. Additionally, an initial estimate of system performance and expected savings is presented, while the planned R&D activities, to be carried in support of the CHEK Project, are described. The recommended R&D solution offers improved space savings, CAPEX and OPEX, and suits the spirit of the CHEK Project in terms of being research led.

In D6.2 (Air Lubrication Concept and Installation Preliminary Design), Silverstream Technologies builds on D6.1 to provide indicative space, power and service demands associated with the installation of the ALS. An R&D solution is presented for the Kamsarmax Bulker in the form of an alternative compressor-to-ARU layout alongside the traditional layout. The traditional layout is also presented for the Meraviglia Cruise Ship. Furthermore, details are provided on the number and position of the ARUs, the impact of the revised design of the ARUs in respect to integration within the Kamsarmax hull form (operating at low speeds), indicative pipe routing, HVAC modifications, electrical connectivity, and preliminary control system design (including cybersecurity and interface information). Finally, the deliverable outlines the results of experimental testing performed as part of the CHEK Project to confirm the ALS’s drag reduction capabilities at low(er) speeds as applicable to the Kamsarmax Bulker.

Silverstream Technologies’ final deliverable, D6.8 (Air Lubrication Final Design) provides the customer(s), i.e. ship owner / operator, with a considered business case outlining the technical and economic viability of ALS for the chosen candidate vessels. The deliverable focusses on three key areas: the design, the operation, and the installation of ALS.

The first part outlines the design and configuration of the system such that it has minimal impact on arrangement of the vessel. The second part defines the system performance considering the most likely operational profile of the vessel, while the third and final part ensures the design of the system is feasible such that it could be installed within an agreed timeframe by a competent shipyard. The deliverable brings together an indicative project schedule for realisation, development, and installation of ALS for both ships with further details on ARU arrangement and structural integration, compressor functionality, selection and positioning (based on ship visit of a Meraviglia Cruise Ship), outline of piping network and valve specification, diagrams of the electrical system, and discussion of the control and monitoring system (automation).

Furthermore, the installation and commissioning activities involved in ALS are presented with a system cost analysis and risk register, while the performance estimate is referenced together with insight into Silverstream’s performance verification protocols. Finally, an overview of Silverstream efforts in R&D dedicated to the CHEK Project including review of the (novel) compressor arrangement, overview of the performance effects of low-speed ship operation through experimental work, and insight into an investigation of the effect air lubrication can have on cavitation and underwater radiated noise (URN) is presented in the third part.

In summary, the deliverable provides the intended customer(s) with enough information to make an informed decision prior to committing to formal discussion with Silverstream Technologies. In addition, the customer(s) will be able to assess the benefits of amending future vessel designs to incorporate air lubrication to increase overall vessel efficiency.

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