As has been mentioned it is pretty situation dependent. I have done a number of deliveries with my wife for instance. In most cases I am going as either the captain
or experienced crew and expect for my air fair to be covered. I she is coming along for the fun of it I pay for her.
If I am returning a boat from a regatta
I raced on the boat at, then it's free for the owner. Unless I was paid to sail at the regatta
in which case it's a business transaction.
If I ask someone to bring their boat back for them because I want to do the crossing as a cruise
, then I would pay for everything except substantial boat repairs
I don't tend to think of there being a hard and fast rule
. Except that if i am being paid for the work then it's the owners responsability.