This sounds like a great idea to me.

There are sites like "Quirky" in which you can post an idea like this. When you submit the idea it creates a community wide brainstorm. You, and other people, can submit ideas for how it would work. If there are enough votes, or the company decides it seems like a good idea, they make it a reality. Pretty cool way to do it and get paid, if you don't want (or can't) to do all the work yourself. Give us a link and I'll check it out too. (By the way, I'd add a GPS tracker to the device idea. Then, it not only floats, but you can track it with a smart phone.)