We booked a cabin on a 10 day crewed charter in the Grenadines last month. The charter fee ($1500/person) included meals and all boat costs. Since there were two vegetarians and a vegan on board the skippers/owners did most of the cooking. We didn't tip them but after the charter I took then out for a nice dinner, the bill was about $40 each, and they seemed quite happy with that.
I did buy the occasional drink on shore at times for them during the charter also.

Drink all day at home, your friends worry about you; do it on vacation and they say "what a good time you're having". Save your friends needless worry, travel more!