The kids don't hold back--they shout, "Look, there are kids on that boat, let's go over and say Hi!" The adults are the same. Some wear neat khakis and polo shirts, but they're likely to be having beers with a group that looks like pirates, with torn T-shirts and no shoes.
If there's an emergency there is no hesitation. Boats converge on the boat that is dragging anchor and tow it out to safe water, even though the owners are ashore somewhere. Someone needs to go to the emergency room and we all open our wallets to lend her money, even though we have never met and don't even know her name. We have no doubt she will pay us back. It might be days or weeks, but she will pay us back. She would do the same for us.
I once had someone toss me a $250 engine part as his boat passed by--I found him two days later and returned the part--he never learned my name or even where I was headed. What goes around comes around.