I think it's Acasti-mer and it's just outside Hennebont at Kervignac Kernours 56700 if you leave Hennebont on the road to Port Louis its just off the first big roundabout.
the exact name is; Accastimer Kervignac 0297812696.You can try also the website le bon coin equipement nautisme Morbihan its a free advertising site and you can find a lot of things for sale