From what I have read:
Some cats will adapt, some won't.
The cat needs to be introduced while at
mooring, for some time. He/she must get used to his/her surrounds before you travel anywhere.
The animal must trust you for any of this to
work.
The medications for
dogs will not
work on cats. The medication for humans will not work on cats. Cats have no histamine receptors, and most medications are anti-histamine meds.
The first time underway, provide the cat some place safe to hide, and be prepared for the rapid cat puke cannon. Make sure he/she has plenty of
water, but don't try any
food.
Food will only make it worse.
Also, understand and be understanding, the cat has no control of this. You put him/her in this situation, so you will have to clean it up, and be happy about it.
Also located his/her litter box very close to the hiding spot.
This is what I have read, so your mileage may vary,
James L