If you want to take your slushy machine (and have the room!), I'd pack it in your checked luggage. Your luggage will probably be opened and checked when they see the blades on X-ray.
You can also buy slushy "virgin" (or non-virgin ) drinks onboard if you don't want to fool with bringing your machine.
Have a great cruise!
"A truly happy person is one who can enjoy the scenery on a detour."