The Challenge

Hoverwork Ltd was an Isle of Wight (IOW), UK based company comprising original engineers responsible for the design and engineering of some of the very first commercial hovercraft made, including the famous SRN1.  The company were designing a new passenger carrying vessel for operation between Southsea (mainland UK) and the IOW.

Hoverwork produced a specification for the ducts:

• 5m diameter propeller
• 15mm blade tip clearance
• Support framework required to interface with vessel structure
• Propeller driveshaft bearing to be supported on a tripod which will penetrate the duct. The tripod is attached to the vessel structure
• Three rudders will be utilised. Top mountings will be off the trailing edge of the duct. Lower hinges and operating mechanisms will be supported via a separate framework mounted on the deck.
• Various load cases were supplied, including high vertical and horizontal g loads.
• Duct deflection was limited to prevent blade tip strikes
• Operation in a marine environment in different locations, including UK and Alaska.
• Rugged enough to withstand abrasion when landing on loose surfaces

Our Solution

Gurit (UK) were the only company whose structural engineers were confident that they could satisfy the stringent structural load cases and engineered the duct using carbon pre-preg and Sprint^TM materials, incorporating structural core, where required.

Support frames were engineering from marine grade alloy tube and plate, whilst Hoverwork Ltd chose to manufacture the rudders from marine grade alloy sheet, much as an aircraft wing is constructed.

The Outcome

The ducts were Lloyd’s approved and as part of the build verification ultrasonics were used for inspection of critical load points and attachments.

PE Composites have built several of these ducts to date and have also manufactured 4 smaller ducts for another vessel, this time from Kevlar and structural pvc core.

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