But the US-carriers are not only for deployment out, they perform several day- or weeklong cruises before every deployment.
All US CVNs spend plenty of time at sea before deployment. Usually in one to three week junkets. There are certain events that have to take place before a CVN can deploy one being
When USN CVNs are stateside and not in a shipyard but in their home port they spend nearly half their time at sea conducting operations.
These are training and/or sustainment cruises and not actually part of a carrier's deployment. In any case, I was wrong about the availability of carriers. According to this article carrier deployments are billed as 7 month periods every 36 months.
The exact breakdown of the carrier deployment cycle is:
1) 7 month deployment period
2) 15 month sustainment period, "in which the CSG will be at its homeport but maintaining a deployed-force level of proficiency."
3) 6 month maintenance period
4) 8 month training period
The 7 month deployment + 15 month sustainment (19% availability) is apparently a matter of money, so in time of war you could theoretically have a 22 month period of availability for each carrier (61% availability). Other articles suggest deployments can actually last up to 9-10 months due to need, I suppose because there are currently only 10 carriers vs the usual 11.
If the PLAN follows a similar deployment strategy, you would expect 1 carrier deployed at all times with 3 to 4 carriers behind it out of action.