GMRS/FRS static, call button not working, which channel?

We want to use our 2 Bell South walkie talkies on a cruise we are taking. 1. One if the walkie talkie gives off constant static. 2. When using the call button, the other does not show which channel. 3. How does one know which channel the other is using? 3. Tell me how to successfully use this to communicate on a large cruise ship. I have read the directions. They are not working according to the directions.