Blake Sea is my favourite. But you'll have to go some to find land to buy with access to it. I have my boat in a rented slip at Hibernia Marina from where I can access Blake Sea. Gull Wing Sailing Club has slips and is a collection of 21 sailing sims. There is also Half Hitch and Free Adriatic in the Blake Sea where you can rez your boat.
Sailing & Boating | Second Life