Hi Raphael,
Why do you like to come onboard a yacht in St Tropez? It is just boring sitting on deck with a silly drink....
Or not!
But anyway, this is the time when yachts are used and with small chances for a guided tour. But perhaps if you are at the right Pampelonne restaurant at the right time and happens to meet an owner of a yacht anchored outside, you might be lucky enough to get invited..!
http://www.villalabegude.com/fileadm...scalet_BIG.jpg