My original intent for this thread was to determine what the international requirements were all about. Which licences, which documentation and when you need them. I intended the thread to be helpful to the many of us that may run into this issue if we take guests or crew (paying/paid/volunteer) across a border.
My current thinking is the same as SailingFools; I would think that a professional captain must follow the laws of the countries in which he is sailing. In international waters, I don't suspect licences apply. I still haven't found any solid information to back that up.
I did not want to call out just one captain/boat as there may be plenty of boats that do this; I'll take those comments to his threads and not side-track this one. I linked to another thread where the specific captain is asked about the legalities but I don't think it was clarified.
If we must hijack this tread to talk about the interpretation of the USCG definitions, then the rule (5a) above has some fudging areas... It mentions "profit", how would you prove it was a profit or a loss? It mentions voluntary, how do you define voluntary? Skipper says it costs $30/day and you voluntarily choose to chip in that amount or is that payment? I know my opinion, but it does leave grey area without known prior examples.
To hijack my own thread further, I have to wonder if it's ethical or wise to try to supplement your cruising kitty, or offsetting cruising costs, by asking crew to pay? As a skipper, I look at crew as people who are helping me out so that I can go sailing. My boat, my dream, my costs. If I were chartering a boat, then it's our boat, our dream, our costs. These mixed shenanigans of "My boat, your dream, who's paying?" is where it breaks down into the grey area.