There is a good website dedicated to hovercraft:-
http://www.jameshovercraft.co.uk/
The Sedam N500 Naviplane was a French attempt in the late '70s to enter the hovercraft market and for a very short time they were the largest craft in manufacture. The whole project was a disaster. The first of the N500s, the Côte d'Argent was destroyed by fire during maintenance after only seven hours service, and the Ingenieur Jean Bertin proved to be totally unreliable due to constant systems failures. It was said that she could not mount the pad at Dover in anything more than a waft of a breeze! Consequently any potential customers backed well away and French government subsidies were withrawn.
There are a few pictures - but subject to copyright. I think this one of the Ingenieur Jean Bertin at Dover is OK though.