HT,
I've shot a few times on cruise ships so I'll take a run at your question.
First of all, you are leaving the US as far as Customs and Border Protection is concerned so you'll need to declare your gear with customs. The easiest deal is to get a Carnet. It's not cheap but it makes returning to the US easier. Go to
http://www.atacarnet.com to get one.
The Internets makes it a lot simpler to get one. Back in the day we used to have to file papyrus carnets. You kids don't know how easy you have it.
There's a greater than zero chance that your ship was built in Europe so electricity in the cabins and public areas will most likely be 220v/50hz. The outlets could be be the UK type grounded plugs, French or German plugs. The poles on the German plugs have a wider diameter than the French plugs and are grounded. One of the UK or Euro B-rollers like Simon W. can tell me to sod off if I'm wrong about the plugs.
What cruise line will you be on? Find out so you can confirm with the ship's electrician.
What brand light kit will you be taking? Are you shooting any sit down SOTs? What camera will you use? Frame rate? Progressive or interlaced? If you're shooting 480/60i under 50hz lights, set your shutter on 1/100 sec to take out the flicker.
Take plenty of lamps for your light kit. Both 110 and 220. Stingers are your friend. The ship's electrician is your best friend. Take a voltmeter and double check every outlet before you plug in. Take a second charger as a backup. You'll be out to sea. There's no going to Kennedy's or Panavision.
It's been about 5 years since I've shot on cruise ship but that's what I can think off the top of my head.
PM with your mobile number if you have any more questions.
That is all. Please carry on.