You understand that the concept of tipping for service is very us-centric. In lots of countries tips are rare when not completely absent and frown upon.
I am an European that have lived in the US since 2001 and I still can't understand why it is considered something acceptable for a employer to pay very little to a worker and expect the client to cover the rest through tips. I, of course, tip as it is customary in restaurants when in the US but not because I agree with the concept but because it is what it is, for me a tip is a tax (20%) like sales tax are also extra (that is for another time.....)
But I feel rather paternalistic to read what I have to do, specially implying that since I am sailing in YC the tips are more warranted. I am already paying a higher fare so sorry but I don't agree with your point of view.