Bottom Paint

[LEWISD]

We have a 2006 225WE that we bought new at the end of the summer in 2007. We kept it docked at Raystown Lake from April until October this year. When we pulled it out of the water it had some blisters near the front on both sides. The blisters are small but cover about an 18" dia circle on both sides. The dealer will fix them this time but tells me they will come back unless I paint the bottom. This is my third Sea Ray. The first two we kept in the water and never painted the bottom and never got any blisters.

Is this necessary? If it is, any thoughts on what bottom paint to use in this fresh water application?

LEWISD
2006 225WE 5.0L Bravo III