We had the bottom painted before launching this year, but we have always pulled the boat out of the water and stored on land over the winter (Ohio/Indiana). Our marina owner thinks the bottom paint will last 5 years with our current practice, maybe 3 years if we decide to keep her in the water year round (heated marina).
It is my understanding that if you plan to leave a boat in the water all year round and just take it out occasionally to wash, etc. you need to apply a barriar coat like Interlux 2000E and then apply the bottom paint like Interlux Micron Extra. The 2000E prevents blisters and the Micron Extra is a blative bottom paint.
Correct me if I'm wrong. I have owned a Hunter and a Beneteau and am just now getting a MacGregor 26X. Perhaps MacGregor's don't blister anyway. But I don't know. I understand the new Tatto's us a material that doen't blister.