Do I need a china visa to take a cruise from Tianjin?

I am a US citizen and residing here with Employment Pass, and my wife has a dependent pass.
We are planning to take a cruise from Tianjin. We will fly to Tianjin on the same day we are sailing.

If we need one, can I apply for multiple entry, since we will come back to visit other cities again in the near future (within 6 months).