Actually, it depends. I have claimed them before.
If you are maintaining a residence for your wife, then they can be claimed as a non-reimbursed business expense. Two ways to do this:
1) Claim the actual value of your mess bill reciepts.
2) Claim the standard IRS deduction of approx $30 a day for meals and incidentals for every day on cruise. When in port, you get the rate for that locality (Honk Kong and Singapore are great).
Really only works if you make the cut-off to itemize deductions (generally owning a house will do this).
Whenever I did that, I had a CPA do my taxes. If you want, PM me and I'll give you the name of the one I used in Oak Harbor.