Removing 10 coats of bottom paint...

[patrscoe]

We hauled out our sailboat for the winter that we recently purchase this Fall and found a few small blisters within about 10 coats of bottom paint. I can repair the small blisters but I am struggling with the bottom paint.

Tried sanding; effective but is taking a very long time for a small area. There is so much paint build up, I'm afraid that I will go right into the gelcoat / barrier coat.

Paint stripper; used two brands; both organic type marine stripper, one being a soy product. Barely removes the first coating. At this point, it will take until Spring, of next year.

Soda blast; received two quotes, $2,000 and $2,200. Must be a cheaper way. If I have the bottom soda blast, apply barrier coat and two thin coats of bottom paint, it will costs over $3,500.

Any experience in removing so many coats at one time?

[deniseO30]

scrapers work, cheap too. your arms will hurt for weeks after. get the type that you pull to scrape, and a good flat file. To sharpen them properly you need a "burr" on the edge. they will remove allot of paint fast but loose the burr in a few minutes.

this shows how. same way for all types of scrapers.
http://www.youtube.com/watch?v=3GY075MVcbU

[celenoglu]

Using heat might be a solution. The wooden boats were burnt to takeof the paint down to the bare bottom. I used a heat gun and scraper for small bottom jobs. If you heat the paint only, you will not have any problems.

[jameswilson29]

You are not alone. I am experiencing the same thing.

Tried Aircraft Fiberglass Paint Stripper (non-organic/lose brain cells) - would remove a little paint in some areas. I estimated it would probably take 6 - 10 gallons to remove all bottom paint, with quite a bit of scraping, too. Scraper was leaving marks on gelcoat.

Briefly tried angle grinder with 100 grit, as recommended by Don Casey. Practiced on the lead keel, then moved to rudder - too powerful, not only removed paint, but also dug into the gelcoat. Quit after a minute or two to avoid further damage.

Bought random orbital sander. Tried 100 grit - too weak, taking forever. I will try a coarser grain next time I am there.

I am beginning to suspect my boat already has a green epoxy barrier coat with identical green color hard and soft bottom paints on it. Yet it is flaking in some area, so I am not yet ready to just paint over it.

[sailortjk1]

If it is loose and flakey, a pressure washer will remove a lot of old paint. A lot cheaper than soda blasting and you can do it yourself. Next I would try strippers and than good old sandpaper. Most likely will require a combination of all three techniques.
Just remember the proper respirator and clothing are important safety concerns.

[Ulladh]

I am with Denise on the scrappers, they are about the only thing beyond commercial soda or other grit blaster that will work.

Most chemical strippers will not work that well below 50 deg F, probably best above 70 deg F.

The advantage with the scrapper is less dust and easier to clean up the chunks that drop on the tarp.

I used combination soy based stripper and scrapper a few years ago to remove 3/4" bottom paint build up over 4 weekends with air temperature 65 to 75.

[CharlieCobra]

We get this all of the time. We use Peel Away and use Visqueen when we run out of sheets, works fine. Trowel it on thick, brushing is ineffective. cover with sheeting and walk away for three days minimum. Come back and scrape off the mess. Follow with sanding using 60 grit on a DA. Apply fresh barrier coat to a wet thickness of 10 mil minimum (usually four coats). Apply new bottom paint and call it done.

[BarryL]

Hey,

I went through the same exercise in 2007. My 1986 O'day had what appeared to be 20 years of bottom paint built up. I tried chemicals, sanding and scraping. The scraping worked best, but would have taken a long long time. I ended up having the the bottom sand blasted. That cost about $1700 but did a great job. I then faired the keel (which was in poor condition), barrier coated the bottom and applied 3 coats of bottom paint (first coat in black, then two coats in red. Now when I see black bottom paint I know it's time to repaint).

The cost of the barrier coat and bottom paint was about $500. This was for 3 gallons of Pettit Protect barrier coat, 1 gallon of Pettit Hydrocoat in black and 2 gallons of red, along with rollers, brushes, etc.

Barry

[patrscoe]

Charlie, You make it sound so effortless.... My arms are still hurting after my last sanding session.
You trowel on Peel Away and you wrap it with plastic. Wrapping with plastic, is that to keep the dusk off the stripper or to contain it or to help the chemical reaction?

[zz4gta]

Orbital sander and the heaviest grit paper you can find. It takes a long time, and you're shoulders are going to scream for days. If it was easy, there wouldn't be 10 coats on there now.