China Visa Free transit Applicable for Shanghai cruise ship stop LESS than 48 hrs ?

U.S citizen...The cruise ship will make ONLY one stop in China, at Shangha seaport. It will be in port for 42 hours and I will get off the ship once for a tour and then return to the ship. As per rules, since only making ONE stop in China and LESS that 48 hours, is it correct the VISA FREE TRANSIT law applies and NO tourist visa required ?

According to Visa Free Transit rules : "Visas are not required for passport holders of the following 30 countries, who transit through Pudong Airport or Hongqiao Airport or seaports of Shanghai, provided they hold valid passports, visas and tickets to the final destination and have booked seats, and stay in Shanghai for less than 48 hours (going out of the airport is allowed)