We usually hauled out and redid our bottom paint every 2-1/2 to 3 years. Here's how we did it.
After 3 years, a good power washing when the boat is hauled from the water (immediately, before the slime and growth has a chance to dry hard on the bottom), then perhaps a light sanding.
First coat of anti-fouling was hard bottom paint. Then 5 gallons (for a 40-foot boat) of ablative (soft) antifouling, in a different color (when possible) from the hard first coat (makes it easier to tell when the ablating bottom paint is almost gone). It is best to spray the self-ablating paint on. If no sprayer available, BRUSH it on. The problem with a roller is that you will be just pulling off the prior coat as you roll it on - just not as effective.
We had a 12V Hooka, home made, that plugged into the cigarette-lighter type outlet. Peter had installed on in our cockpit. You can see pictures of it at http://www.fototime.com/inv/19FAEC458BFF5BC
Please note that the truck tire inflater is a high-pressure, low volume air source. That is the reason for the accumulator bottles. Because of the high pressure, it is absolutely necessary that a scuba regulator be used. The pump is a diaphragm pump, so no oil gets into the air line.
Even though you would not be going very deep with such a hookah, I believe you must be knowledgeable about SCUBA diving to use it. Peter and I both took SCUBA lessons before we went cruising, and I do feel that use of gear such as this, or a commercial, hookah, requires the same knowledge as you get in a SCUBA course. You can do great harm to yourself if you make a mistake.
That said, this hookah proved invaluable to us for a lot of problems, such as cutting fishing net off the prop.