Stupid question, can I start sanding and prepping top half while still getting her wet? I figure the paint is shot anyway and it's all white, won't look that bad sanded down and I can keep from going through river withdrawals while I get her ready for fresh paint to put on this winter. Obviously I know I'll have to really clean the surface before painting.
Well I have done plenty of auto painting but not much in the way of boats. So im only speaking from auto body knowledge.
I dont think I would take the chance on using your boat while working on the exterior. I have seen guys take cars, get them straightened out and primered. Then they drive them for a season or 2 until they are ready for final paint. Then once the final paint is complete they end up seeing problems like bubbling etc later down the road. I contribute it to the primer soaking up water and contaminents while it was in the elements primered.
You might get away with it if you plan on sanding really well and reprimering before final paint but I dont think I would chance it. A few bubbles can ruin an entire paint job. I also believe any body fillers you use are capable of soaking in water. So you defanitly dont want water logged filler under paint. I have even heard that fiberglass uncoated can soak in water.
anyways I cant answer for certain but my .02 is to hold off until your ready to paint.