A cruise ship will usually have multiple access points you can connect to. Some will be better than others for various reasons. If you had a way to select which access point to connect to and a way to boost the signal into your cabin, you could be ahead of the game.
The access point you connect to can make a huge difference in throughput in my experience.
Some experimentation might be needs, but I wouldn't be surprised to see the same SSID on different channels and some will be better than others.