when does taking people out on the boat considered buisiness

[mrmacey]

if you have freinds of freinds who are willing to give you good gas money to take them out for a few hours is that considered ilegal as long as im not advertiseing and not chargeing set rates but instead opting for some gas money how do pros feel about this is it cutting in or is it a smart thing to do fish myself and get gas money to boot let me hear your thoughts on this!! heres my delimia my sister owns a hotel in newport some of her cleints would love to go fishing or just around the harbor for a cruise they are willing to pay GAS! there her freinds they know im not a buiseness just somebody with a boat can i leagaly take them out as long as what they are giving me is not asked for but kinda like help me with the gas i know ive been out and through people gas money its a courtesy thing and didnt think twice about it but i see buying the bait supplying bevrages gas expensive and need help!!