Cruising to mainland China from Hong Kong

Hi
My wife and I are UK Passport holders and will be travelling to and arriving in HK on the 7th April 2015 staying there for 2 nights then joining a cruise ship that will eventually arrive at Tianjin early on the 21st April for a three day stay. The ship will then cruise to Shanghai arriving there on the 26th April. At this point we will leave the ship and transfer to a hotel for 2 nights before travelling on to Japan
Can you confirm that we will need to apply for China Visas covering two visits and that we will need to state the precise dates of entry into China on the application forms
John from Essex UK