One of the biggest problems in deterring raccoons is that they are so very intelligent. Lights, sounds, etc. may scare them off (well scatter them) for a while, but won't phase them once these things become a "normal" part of their environment. From sharing our home with Annie for almost 10 months what I have learned is that CHANGE unsettles them. In the home environment, moved furniture, new visitors, or a change in routine was distressful to Annie. Also, if you "piss one off" they get really mean and aggressive and won't hesitate to attack.
Although any mammal can be a carrier of rabies, skunks, possums, and raccoons seem to get the worst end of that deal. I would be much more afraid of the disease and infection from a simple bite.
To deter them, try doing different things or "attacking" them from different directions -- switch it up - try the water hose one day, a can of rocks lobbed in their direction another. Keep them unsettled and wondering what will happen next. Have some fun with it
I don't want to give the opinion that I consider myself a Raccoon expert or a know-it-all. My comments are based on first hand experience from having closely observed raccoons both in the wild and from having raised a little orphan, Annie, who shared our home for almost a year.