By early afternoon, fears were growing for his safety, after friends and family failed to contact him, and a Mayday alert was launched.
Soon afterwards, the Mascaret III was found empty in Soorts-Hossegor, a well-known surfers' beach around 15 miles north of Biarritz.
The emergency was then escalated, with two speedboats and three helicopters scrambled to try and fined Mr Agnes, who was officially declared 'Missing At Sea'.
The 'Eole', a ship that was in the area, also got involved in the search for Mr Agnes, a businessman renowned for his love of the outdoors.
He is a former international surfer for France who joined Quiksilver 30 years ago at their European HQ in Saint-Jean-de-Luz.
In March 2015 Mr Agnes became CEO of the brand, which was founded in Torquay, Australia, in 1969 before moving to the West Coast of America.
Soon after Mr Agnes took over, Quiksilver changed its name to Boardriders, as it took the Roxy and DC Shoes brands under its corporate umbrella.
It is currently involved in an ambitious bid for Australian rival Billabong, in a deal that would significantly increase its multi-billion turnover.
Despite being so heavily involved in his worldwide business, Mr Agnes spent as much time as possible in his beloved south-west France.
He is well known for being extremely down-to-earth, and shuns publicity for a simple outdoor life.
A Quiksilver spokesman in France said Mr Agnes was 'a seasoned sailor who was used to fishing in the area'.
He said the alarm was raised following the discovery of the empty boat on the beach at around 9.15am - some two hours after Mr Agnes had set off.
By 6pm, those looking for Mr Agnes were reporting 10ft waves in the search area, and increasingly poor visibility.
'As night draws in and temperatures drop, the search will become increasingly difficult,' said a spokesman for the local prefecture.
- Daily Mail
