Description of the Proposed Paper

To set out current advances in Air Cushion Vehicle (ACV) technology and planned future developments including the results of recent trials.

Application

The Arctic environment presents a number of challenges, the extreme cold, ice and weather conditions combine to create difficult operating conditions. Many of the logistical/Escape Evacuation and Rescue (EER), solutions proposed can provide an effective solution during certain times of the year, but struggle to provide year round cover; particularly in regions where significant ice ridging can be found. The ACV has the potential to fulfil these roles, carrying significantly higher payloads at lower cost, maintaining operability and a proven safety record when compared to helicopters, while providing a swifter response at reduced cost when compared to ice breakers in a number of ice and weather conditions. ACV designs have been documented as having a low impact on the surrounding environment and have a minimal below water acoustic signature providing a solution for crew change, routine and emergency resupply and EER.

ACVs do however have a lower operability envelope in heavy seas and can be affected by ice surface features such as rubble fields and ridges, and so one of the key risks to mitigate was ice ridge height. Initial studies confirmed that an ACV needed to be able to cross ridges up to 2.75m in height to effectively operate in the Alaskan region, and hence ridge crossing trials were proposed by Shell to develop a momentum balance equation to establish thrust requirements for ACVs to cross ridges of a specified height and full craft width.

Results, Observations, and Conclusions

The ridge crossing trials involved the use of the largest hovercraft in Griffon Hoverwork (GHL) range, a BHT 130, 30m in length capable of carrying 130 passengers with a unique ice ridge crossing skirt design. The ACV was monitored using a suite of sensors and was run over simulated ridges of different cross sections to test; friction coefficients, yaw angles, heights, and speeds. The conclusion was that it would be entirely feasible to develop an ACV capable of a controlled crossing of a 2.75m ice ridge whilst maintaining a safe approach speed. Shell is working closely with GHL on planning the next stages of technical development with a view to a future deployment of an ACV. Further developments revolve around a technology roadmap which has been outlined to examine the key technologies that could have a significant impact on ACV design, and explore how they can be supported and implemented.

Significance of Subject Matter

The ultimate aim is to produce a new breed of ACVs with variants encompassing routine resupply/passenger transport, heavy lift and EER that can provide an integral part of the logistical and EER solution for the Arctic whilst minimizing the environmental impacts of the work.

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