You can look at our Alcohol FAQ
for detailed information and links to the cruise line rules. RCI no longer allows their passengers to buy bottles aboard their ships for cabin consumption.
They do check all luggage either manually or electronically, and I have known people on RCI who have had alcohol confiscated on embarkation day.
The official policy of this forum is to support the cruise line rules and not condone smuggling. Therefore I will close this thread since the FAQ answers your question.