eppo said..
Looks like I finally agree with NoBs for once.
Let them float, but keep an eye on them. If after a while, you feel it could get dangerous, then you are duty bound to rescue.
Infact I'd say if this person died, was seriously injured i reckon a good lawyer could have your ass on a plate.
But nothing like a good long swim to wake some people up.
You're not actually duty bound (whether you think you are morally bound is another issue) to do anything - especially if you think going out to help could put you in further trouble. Best thing to do is call the rescue service. The laws of the high seas (rendering assistance) don't apply to us. In those instances a minimum amount of safety equipment is required to be carried by vessels and they can help out, even if it is just standing 100 m off and keeping note of the distressed vessel's position.
In fact, if you decide to render assistance, and then realise it's all too hard and decide to kite off, you put yourself in a worse position - in that instance, because you have decided to help, and established a duty of care. You could only kite back to shore if you were doing so to seek help or if the dude explicity said to you, "I'm OK, I don't need your help"
That said, keeping an eye on each other and helping out when we can is what has made this sport so good. It's all about striking a balance I guess. All of us (most of us) while learning have done something that has required a long swim or a packdown - it's part of the learning process.
And that brings me to my personal axe - being fit for the sport, which means being able to swim 2 - 3 km with no dramas.