If you don't think a cruise ship is a "real job," maybe you should think twice about applying. I've done ships. Going on stage with little to no rehearsal and sightreading a show the first night on the ship is a "real job" as far as I'm concerned.
You NEED TO BE READY before you go on a ship. A ship is not a place to learn styles and chart reading. Most musicians on ships have a lot more experience than someone coming out of college. There are people who will take you under their wing, but like I said, my first night on a cruise ship I was sight-reading a production show. It's trial under fire. That being said, here is some friendly advice.
1. Be an excellent (chart) sightreader. This is the #1 most important thing. You must be able to not only read charts, but interpret them as well. Get Houghton's Drum Set Reading Anthology. This is a great book to prepare you for chart reading.
2. Know your styles. Be prepared to play anything. Just a few styles I played on ships have been - 2 Beat, marches, dixieland, second line, polkas, small group jazz, big band jazz, waltzes- all kinds, reggae (including filling in with the all Jamacian Reggae band on the ship), soca, songos, mambo, cha-cha, hip-hop, rock, country, etc...
3. If you do land a gig, bring a mini-disc recorder or other portable recording device. I did not get the liberty of rehearsing much on a ship. If a fly-on act came in, we may run beginnings and ends of tunes, trouble spots, etc. The rehearsals were over so quickly that I needed to have the mini-disc to review before the show.
I don't want to burst anyone's bubble, but I'd rather see someone overly prepared. It's much better than being replaced after one cruise.
Jeff