I coated a boat last week with a water-based polyurea. Nice stuff to work with, water-clear once it dries, very high gloss (not to everyone's liking), fast drying (was able to get 6 coats on in one day, could have done more but 6 seemed like plenty). The solids content is very low compared to solvent-based coatings, but it built a film quickly. I haven't paddled the boat yet so I don't know how well it will hold up in use. So far it seems very tough, and I'll know more this weekend when I take the boat out for a test drive.

A common problem with water-based polyurethane is that it can turn milky white when it is wet for a while; I do not expect the polyurea to do so (it is resistant to very nasty solvents, so water should not be a problem).

Despite being water-based, the product that I used is far from non-toxic; it has very little odor, but a respirator is recommended. At least it is easy to clean up!