You are looking for winter space quite late in the year! We looked into wintering in Athens last year and had no luck. In fact, I must have emailed 10 different marinas
looking for space in July and winter, and not one responded positively! "Sorry we have no space" is all we got! Then I was introduced to a local yacht agent by a resident Athenian boater we met in Patras. The agent found me a space instantly in Agios Kosmas Marina for our July visit. But by then we had already booked a spot in Crete, so wasn't trying for winter. This year when we wanted to go back for a week in August, they again said they had no space, until I told them we had been there last year - then they found us a spot! The cost was the same with the Agent as it was when we booked on our own this year. I could not recommend Agios Kosmas any more(built for the Olympics
, and owned by the government
for now). The cost is reasonable, it's just north of Glyfada and right on the tram line. The only negative is depending on where you get berthed, it can be a long walk out to the road - it's a very large and very secure marina. About half the taxi drivers we had didn't even know it existed! But it does not have any fancy facilities. And we, a 50' cat, were definitely among the smallest boats in the marina. I would recommend calling them - they are not good at answering emails!