Projects: Strip Ablative Bottom Paint, Paint with VC-17
Sanding scores of "blisters" between the barrier coat and gel coat every season before launch finally persuaded us to go ahead and remove the existing barrier coat, give the hull time to dry over the winter, then re-barrier coat in the early spring. Time constraints and weather conspired against us, however, so the decision was made to remove the ablative paint then prep the hull for VC-17, leaving the barrier coat alone.
This is the progress I made in about two hours - from setup to cleanup - using a Porter-Cable 6" random orbit sander with 60 grit paper. The gray is the Interprotect barrier coat, and the red is an anti-fouling paint used to indicate thin spots in the blue ablative.
A close-up shot of the hull reveals more "blisters" - the dark spots - waiting to emerge. As I began sanding, I uncovered hundreds of these spots that have moisture trapped between the barrier coat and the gel coat. The darker circle in the upper-middle part of the picture is a previously epoxied "blister".
Work began at 10am and ended at 11:30am. Switched to 40 grit and cut through the bottom paint much faster. It's still a tough job no matter how you slice it. Once all the ablative is off, it's time to sand to gel coat with a finer paper.
I made a lame attempt at keeping the mess to a minimum by laying down a couple of drop cloths. It didn't do a whole lot of good. I still ended up with blue dust all over the ground.
I began work at 10am (again) after plugging into shore power, running an extension cord from inside Ariel, and suiting up in a Tyvek suit with gloves and respirator. It was a balmy 31 degrees when I started working and my fingers quickly froze with only latex gloves on. I slipped on a pair of wool gloves that happened to be in the car and kept going. After only a few minutes of sanding, my shoulders were aching so I decided to try the paint scraper I'd bought a couple of months ago. What a difference!! The scraper skimmed the paint off, revealing the barrier coat, with only a moderate amount of effort. I was amazed by how easy it was compared to sanding.
Four hours after later, I had stripped almost the entire hull, leaving only a few tough spots that I'll have to attack with the sander due to the angle of the hull. I still can't believe how much more effective the scraper is than a 6" random-orbit sander with 40 grit. I'm a believer.