Tips are pooled by the whole crew (unlike on bigger ship where you might tip your waiter and cabin steward directly). On Flying Cloud last year folks were tipping $25
per person per week for the 6 day cruise. We tipped a bit more. Tips were put in an envelope then deposited in a box by the bar on the last night of the cruise.
For the cruise on Amazing Grace I could see tipping about $50 or $60 per person for the 13 day .