I spotted her on the 31st of August running in Southampton Water, and I had seen her previously at Griffon Hoverworks on the Itchen. She is a military/naval hovercraft, but I do not know which country she is from or what her name is.
As a teenager, I remember a pretty rough crossing to Calais on one of these!
I took this photograph from a Bristow Search and Rescue (SAR) helicopter, based at R.A.F. Manston, Kent with my father as duty SAR pilot that day.