For leisure sailing and socializing, try SYC (Shanghai Yacht Club), foreigners welcome. Recommended !
Open sea sailing :
The chinese fear that you (deliberately or not) comes close to any military post or port, makes it out of question for a foreigner to go unattended at sea.
If your wallet is heavy and you are really itching for it, rent a boat
(with chinese certified captain).
Then you might have the chance to be at the helm
In these days, there are anti-US propaganda and indoctrination in China, so it may not be as easy as before to just stroll around...
I'm now asked frequently on the street "are you american ?"
Before they asked me "are you german ?"
Don't go to China in these virus times.
Let your Winnie-the-Pooh T-shirt stay in your home country.
In the aftermath of the Kunming massacre in 2014, train travel are now almost as strict as flight travel, considering luggage and what you can bring aboard.
China belives as strong as americans, that THEIR country is the best. Leave your thoughts of the regime at home.
中国 (Zhong Guo, the name of China in chinese) translates to ďCentral Country".
When the time comes, have a nice trip to China !