I hear you, 50% looks too much right?
Well, consider how much you'd be paying for the meal you are getting if in a real nice restaurant on land, more than $40's worth right?
Then consider the extras you get at Palo, being able to order multiple items to try.
Then consider the service from these folks who I am told get paid very little if anything of a salary. They rely on your tips.
If they treated you very well, and you are on vacation, on a wonderful cruise, treating yourselves very well, don't over think the % you are giving as a tip. If they treat you very well, treat them very well in return. Carma baby
Just my 2 cents.
Eric