"Any charge above your own food contribution, personal visas and permits, etc., constitutes a "commercial venture" with dramatic and serious insurance and legal implications. Paying for any fuel, dockage, etc., makes you a "paying guest/passenger"
Intimidating as it may be and whilst I accept the crewfinder rules on this forum, following a thorough look at all threads on this subject, I would like to challenge the "cost sharing is highly illegal" school of "legal opinion" that has prevailed simply on the basis of anecdotal information from certain jurisdictions with regards to this subject, and a fair bit of guesstimating.
To my mind, the line that was drawn in this instance seems purely arbitrary without any basis in fact.
The regulation of amateur boating in the EU alone varies to such an extent that I would not dare produce any blanket "legal advice" regarding the legal and insurance implications of cost-sharing arrangements and the like for my own flag state of choice - let alone on a worldwide basis. The quote from France for instance seems to suggest that they want to stop foreign charter companies operating without VAT registration, not siblings/neighbours/acquaintances sharing the petrol or docking costs to get up the coast on their joint holiday. You just wouldn't get anyone prosecuting that. How would the courts to determine if sailing buddies are actually friends or a businessman and his/her customer?
It would be of interest to see some actual test cases from common law jurisdictions (if there are any). I would assume that outcomes would differ widely depending on the jurisdiction and the merits of the case at hand.