DGillies:Having worked at a yacht club for over 30 years, I'd like to say that the only difference between a yacht club and a marina is that a yacht club is owned by all it's members, whereas a marina is privately owned.
Careful, there can be marinas that are publically owned. I would hate for this category to neglect the publically owned marinas (called Ports de Plaisance in French). Because this would exclude opportunities for a lot of seaside facilities in France and Europe.