Call the cruise line and see if they have sewing machines for you to use. A small feather weight might work, packed really well in your luggage. Not sure of their weight, but someone here can tell you. I have carried one on in a well padded bag....but I wasn't going to be gone for a month! Wow! that is so wonderful you are able to make this trip.
Oh, instead of hexies, why not Yo Yo's? You can make, vests, pillow covers, quilts etc. out of these. Use an accuquilt machine with a circle die and punch out hundreds....easy to make while traveling.