Application Example – Marine Hovercraft
Eliminating the need for two out of four diesel engines, Griffon Hoverwork adopts YASA motors and reduces noise, complexity and cost of its latest craft.
Griffon Hoverwork designs and manufactures hovercraft from its base in Southampton in the UK, and traces its roots back to the earliest days of hovercraft and Sir Christopher Cockerell. Today, it has to compete fiercely with alternative forms of travel and its sister company Hovertravel operates the only passenger hovercraft service in the world.
Constant innovation is necessary in this market, so when Hovertravel wanted to find a method of improving engine efficiency it turned to YASA Motors. In existing hovercraft designs, four diesel engines had to be used to provide propulsion and lift, and to give a degree of security for ‘mission critical’ applications. As well as being inefficient, the engines resulted in a great deal of local noise next to the passenger compartment, reducing the comfort of passengers. Two bow thrusters were fitted which were fed by bleeding air from the lift system.
YASA engineers selected the YASA 400 design from its range of proprietary electric motors. YASA’s motor technology is unique, and capable of world leading levels of power and torque density from smaller and lighter motors. With minimal modification, two YASA 400 motors were incorporated into the design of the GHL 12000TD hovercraft. The electric motors were deployed as bow thrusters to provide reversible sideways thrust for craft manoeuvering at low speed.
The principal benefit of using YASA electric motors was that two of the four diesel engines could be eliminated from the design. This directly reduced the noise levels from the engines significantly, without impact on the reliability of the craft.
The YASA motors also provided greater flexibility in manufacture as their small size and modular design means that they can be fitted late in the build programme. The advanced yet simple design will be easy to maintain throughout the life of the craft.
Other benefits in the design included a reduction in the cost of the control system through a simplification of the bow thruster system.
The first products are being built for Hovertravel to take up to 88 passengers and crew from Southsea to the Isle of Wight. The new, sleeker hovercraft will bring quieter journeys and a quicker turnaround. Combined with other improvements the overall manoeuverability of the hovercraft is significantly better than the current hovercraft.
'We are taking the propulsion system down from four engines to two, and this brings the major benefit that noise is reduced by almost half”, says Chief Pilot Peter Mulhern, who has been involved in the plans for the new craft. “The use of YASA motors on the new GHL 12000TD hovercraft has allowed the design team the flexibility to meet the demands of our market in a significantly quieter and more efficient system package.”
The new GHL 12000TD hovercraft is 22m long and 10m wide, has a payload of 12 tonnes and is suitable for military, paramilitary and naval forces use as a logistics or amphibious operational support craft a well as its use for passenger ferry services.
The craft are due to be in service in early 2016.