Joost, the marina rates here vary considerably, but just to give you an idea, my boat, which I own - not rent, is 33-feet long and the monthly fee to keep it tied to a concrete bulkhead in Marathon Key, Florida was U.S. $754, plus another $20 for 30-ampere electrical connection.

If you wanted to rent a 12m sailing yacht, roughly 36-feet long, the cost here is $320 to $460 per day if you don't require a captain or crew. If you do require a captain, the price is usually about $200 more per day.

Cheers,

Gary