Multi-season ablative
Try any of the multi-season ablatives. If you're like me and don't like to inhale poisonous sanded material and get enough other painting duty at home, its worth the extra up front $$$ for the stuff. Assuming whatever is on the bottom of your boat now is in reasonable shape, you don't have to do much more than rough up the surface with sandpaper before applying the new paint. With some epoxy paints, you have to remove the old layers. I used the West Marine house brand msa, and it did a good job for two seasons (I'm on LI Sound in CT). No hard growth at all. It was on sale and a good buy, about $90 for a gallon if I remember correctly. No similar bargains this time, so I'm trying Micron CSC this season. I had a coupon so I spent about $115 for a gallon. It was really easy to apply.