US passport, travelling from LAX to Shanghai by Delta Airline, staying 2 nights then go on cruise.

Hi,
We are (husband & wife) US passport holder who will flying from Los Angeles to Shanghai Pu Dong airport via Delta Airline on Feb. 23, 2018 and staying in Shanghai's hotelfor 2 nights only.
Then, we will be leaving Shanghai on Feb. 25, 2018 from Wusongkou International Cruise Terminal in Shanghai to go on a Mejestic Princess cruise.

The Cruise itinerary is Hakata (Japan), Busan (South Korea), Hong Kong, Ho Chi Minh city (Vietnam), Bangkok (Thailand) and last destination is Singapore. I then will be flying back to the UK from Changi (Singapore) airport.

Our question is will 72 hour visa-free transit covers other mode of transport not just airline as we will be leaving Shanghai (China) by Cruise ship.

My other question is as long as we have all the paperwork such as airlines tickets, hotel booking for 2 nights stay in Shanghai, Cruise ship itinerary and booking confirmation. Would we qualify and be able apply for 72 hour free transit once we arrive at Shanghai airport.