Re: Tipping a charter Captain?
As DJ has said already . . . it depends on the level of service. If anyone goes out of their way to add extra value to their service than of course a tip is in order no matter who is providing the service. After all, they should be trying hard to please IMO if they are looking for referrals and returns trips.
You won't insult the Captain for offering a tip, but if he went "overboard" (maybe not the best analogy here

) you would insult him for at least not offering.
Your friends sound like they have short arms
Have you noticed when they are in a restaurant the need to go to the bathroom as soon as the bill hits the table . . . hahahaha
When ever I'm out on a friends boat for the day, even though they invited me, I still offer to pay for some of the gas (95% of the time they refuse to accept it anyway). Guess it's just a factor of how I was brought up!
I would never go over someones house for dinner without bringing a bottle of wine. It really ticks me off when they put it on their rack and never offer me any . . . Go figure!
The guy who cuts my hair "owns the shop" and I still tip him out!