[MrAC1980]

How big of a boat? I have a pretty big (heavy) 21ft on a roller trailer. I lower the front of the trailer/boat as far as I can, then put blocks in the back of boat. I use double row of cinder blocks on each corner with a few pieces of 4x4s so the blocks dont scratch the boat. Then lift the front of the trailer as far as i can, which in turn lifts the back of the boat off the trailer. Then I paint the bottom that is off the trailer. Let it dry for a few hours, then repeat the process putting boat back on trailer. Then I do reverse, raising front of trailer/boat as far as I can, then blocking the front of the boat, and lower the trailer down and paint the rest of the bottom. Hope this helps, I've done the whole process of removing the trailer from under the boat and it sucks... good luck, go slow and having a few buddies to help makes it easier/safer.