Townvet, the "proper" way to bottom paint a boat is, first, the area to be painted has to be lightly sanded, cleaned with denatured alcohol, then two coats of epoxy barrier (the only thing that is waterproof is epoxy, the gel coat is not), then two coats of bottom paint of your choice. I prefer the bottom paint to be first coat one color, second coat different color(blue and black for example). The first coat would be the indicator as to how much and how long it takes for your bottom paint to wear off. So, lets say if you have black over blue and in the middle of the season you see a spot of blue bottom paint instead of all black, you have to touch up that area.
P.S, not all the dealers go thru all that, especially when the "throw in" the bottom paint job. Insist to be done that way even if it costs a bit more, no worries for blisters.