This shouldn't be called an " attack "--- from all indications now that the incident has been checked out --is that the sting ray jumped from the water, which they are prone to do---the boat was going approx. 25 mph. and the hapless lady just happened to get hit by the ray. A freak accident but not an attack. I'm fairly sure the ray wasn't just cruising about waiting for a boat to come by so it could launch an attack against someone.
Like bookitnow said, there are so many things that can happen, you can't worry about them all, especially something so freakish as this.
Go--cruise--boat--swim with the rays-- all will be well--probably.