Sorry to be MIA so far on this important topic. Not sure I have anything useful to add, as y'all have already gotten to the windsurfing exemption statute.
One thought is to get the definition of "vessel", for starters. I can't in any way construe that word to mean "kiteboard" since you can't ride a kiteboard (without the kite powered up) as you would a canoe, powerboat, etc. It won't under any circumstances float a person. So there may be an exemption in that fundamentally a kiteboarder is constantly expected to swim when required. Being more of a swimmer than a boater, if you see my meaning (I'm also thinking "more of an aircraft than a boat", at times, too - ha - but I'll stay on topic).
The Utah laws don't require life vests for people who swim, do they? Nope. (hey, maybe there's a hot libertarian argument to make, akin to helmets for motorcycles). Thus, aside from the well-argued safety issues which Bordy laid out so well in his letter, there is the parallel to swimmers. Swimmers with kickboards, swimmers with inner tubes, swimmers with big powerful kites and huge grins on their faces.
I think the original intent of life vest laws is to protect people who go out in boats that are not prepared or able to swim to safety in case of a problem. That's reasonable and prudent. Children, older folks, non-swimmers, etc., all vulnerable, get taken out on boats and boats can sink.
Kiteboarders, on the other hand - and this is the crux of the argument -
are always prepared to swim at any time, and are equipped with wetsuits to do so safely. (Could argue also the point that wetsuits have buoyancy.) After all, if the wind dies, which could happen at any time, kiteboarders have no other way to get back and are thus at all times assuming the risk of having to swim back. Just like a distance swimmer. Nobody kites who isn't prepared to swim back from where they are kiting, right?
I think an argument about the definition of "vessel" is the key one. These guys at DNR do not want to start having to spend their time pursuing kiteboarders and issuing tickets. They're underbudget and understaffed enough, I bet, and have all their other responsibilities for the good work they do. Maybe this would be a very acceptable way of them saying to their management, "Hey look, these aren't boats or vessels in any real sense of the word so the statute isn't applicable and we aren't going to bother."
I see the SUP totally differently, of course. I don't agree with the requirement, but could see the regulator's point, with the risk of children, cold water, whatever.
(later)
OK, just found an interesting piece of info that may be very germane. In 2009, the US Supreme Court,(yes, really!) with regards to a court case involving the USCG, upheld that to be considered a vessel, "watercraft must have a practical use as transportation on the water". Here's the link:
http://www.piersystem.com/go/doc/786/26 ... g-docksideSeems like a clear definition to me. Rowboats, canoes, aircraft carriers - yes. Maybe even a SUP (and this would be a big stretch). But a kiteboard? No way. For if there is little or no wind, which is frequently the case, no
practical use as transportation possible.