Luggage is scanned on all cruise ships, same as at airports at all ports. If this throws up anything suspicious, they will then do a search.
I cruise with Princess all the time and have never had any alcohol confiscated, have always took wine and beer on board. If you buy spirits from the duty free shop on board they keep it and deliver it to your cabin the night before you disembark.
All wine can be brought on board but spirits are delivered to your room on the last evening .
Generally it is a full body search on princess cruises.
Our bags were scanned on boarding and every time we returned to the ship . We took some wine with us and bought wine from our days out . At no time was any of it taken from us. The only time they take it is if you buy it from the duty free on board .Then you get it delivered to your room the last night.
We took our spirits on board the p&o oceana and had no problem even though our bags were scanned and we bought spirits in the caribbean islands and never had it confiscated again bags were scanned. Beryl. Birmingham.
You can take wine on at any port of call they may take spirits on but if you put it in your main luggage you can keep it .