if you are not at the helm or controlling the movement of the boat you are a guest and nothing more. The second you take any move to even advise the guy driving you can be suppoenaed in an investigation if there’s an accident and if it comes out you are licensed then who the hell knows what would happen.
So just enjoy yourself and don’t go out on the water with idiots. I had to take over on a pleasure boat once because the guy driving (the boat owner) was taking us into peril (he sideswiped a bouy). After the party ended several people came to me to thank me for taking over when I did. Needless to say that I didn’t get to do any drinking that night which sucked cause it was a PARTY!