http://www.public.navy.mil/BUPERS-NP...DutyCodes.aspx
Summary: Everything's classified (broadly) as sea duty or shore duty for the purposes of the rotation. Your first station will be something that is considered sea duty, which usually (though not always) means a ship that goes on deployments every so often.
You seem to be confusing the term "sea tour" with "deployment". A sea tour is a period during which you're assigned to a sea duty station. A deployment is when your ship leaves home port for several months.