Floating Bridge from shore to mid stream pontoon above Yarmouth IOW-How does it work?

[zambant]

Some while ago I went up the river above Yarmouth on the IOW and saw an electrically powered "pontoon" going from the shore to the mid stream pontoon.
I think it had the name "The Yarmouth Traveller" and was near / in The River Yar Boatyard

Can anyone tell me in some detail how it works please?

Thanks
John