Most of the trips I have been on, the cash just gets dropped in the jar without counting. So, they don't really know who gives how much. I tend to tip well, so I give them a check so they know what I gave.I have been told that the skipper always hands out the tip money and gives a full accounting of how much and where from. the crew know who butters their bread and they had e very long memories and I am sure they discuss who the passengers are in advance of the trip
That being said, I think these guys are such professionals that everyone, regardless of their tipping status, is treated very well.