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casey1999 04-18-2013 06:56 PM

Removing Bottom Paint
 
I need to remove old anti-foul bottom paint prior to applying new paint.

I have seen in the US most people use a sander, while overseas it seems scraping using a large scraper is used. Scraping may be cheaper (last time I sanded and the paint cloggs the sand paper quickly- went through a lot of sanding disc). Scraping might also be environmentally better as it seems to generate less dust.

Comments on best method?

fallard 04-18-2013 07:39 PM

Re: Removing Bottom Paint
 
I've used a carbide scraper to remove built-up bottom paint on two boats. It's work, but it goes right along and it's a lot less messy than sanding. The carbide really holds its edge and there is no sharpening required. The sharp edge will literally fracture the bottom paint where it's thick and you can scrape the thin parts as if you are planing wood. I don't know what your options are for a power version, but you might damage your gel coat too easily if you aren't properly skilled. You can buy these scrapers at a hardware store, Home Depot, etc. and you can buy replacement blades, but you won't need them if you start off with a new scraper.

casey1999 04-18-2013 07:43 PM

Re: Removing Bottom Paint
 
Quote:

Originally Posted by fallard (Post 1018229)
I've used a carbide scraper to remove built-up bottom paint on two boats. It's work, but it goes right along and it's a lot less messy than sanding. The carbide really holds its edge and there is no sharpening required. The sharp edge will literally fracture the bottom paint where it's thick and you can scrape the thin parts as if you are planing wood. I don't know what your options are for a power version, but you might damage your gel coat too easily if you aren't properly skilled. You can buy these scrapers at a hardware store, Home Depot, etc. and you can buy replacement blades, but you won't need them if you start off with a new scraper.

Sounds good. I would plan to use the non-powered version. I think I will give it a try.
Regards

DannyboyUpstate 04-18-2013 07:44 PM

Does the carbide scraper remove the anti-fouling and the barrier coat down to the gelcoat? I have to remove both and start over.

fallard 04-18-2013 07:45 PM

Re: Removing Bottom Paint
 
Another thing: cover yourself as completely as possible. Get a tyvek suit, gloves, a good dust mask, goggles, etc. You will get some fine residue and it will not be nice when you get it in your eyes or nose. It's bad enough on your skin.

You ought to put down a drop cloth to catch the old paint. It should be required if it isn't. I used discarded shrink wrap last time and threw it out with the old paint debris.

fallard 04-18-2013 07:49 PM

Re: Removing Bottom Paint
 
Quote:

Originally Posted by DannyboyUpstate (Post 1018233)
Does the carbide scraper remove the anti-fouling and the barrier coat down to the gelcoat? I have to remove both and start over.

If you get down to a barrier coat (Interlux 2000?) that is well adhered to the gel coat, you'd be better off to switch to sanding if you absolutely have to remove it. If the barrier coat is in good shape, I'd sand it lightly and wash it with the solvent recommended for the new barrier coat.

DannyboyUpstate 04-18-2013 07:59 PM

Quote:

Originally Posted by fallard (Post 1018235)
If you get down to a barrier coat (Interlux 2000?) that is well adhered to the gel coat, you'd be better off to switch to sanding if you absolutely have to remove it. If the barrier coat is in good shape, I'd sand it lightly and wash it with the solvent recommended for the new barrier coat.

Well, this is a boat I just bought last fall. It sat on the hard for 20 years. It was on the ocean, and I'm lake sailing. I have no idea what the old paint is that's a problem because I want to put VC-17 on it and it must go onto its own barrier coat or it won't be right.

fallard 04-18-2013 11:03 PM

Re: Removing Bottom Paint
 
The primer for VC-17m is Interlux 2000E, which is also a barrier coat. If you strip the bottom paint and get to a clean, hard surface and prep it with the appropriate solvent (202)for the 2000, you should be fine. I've used that system for both boats that I stripped. I didn't use VC 17m, but used CSC or ACT ablative copolymer bottom paint (both Interlux products) and it has worked very well.

After you apply several coats of the 2000E, you'll have to let it cure for a while before applying a vinyl bottom paint like VC-17. Interlux also recommends sanding the 2000E with 180 or finer grit before applying the VC-17m.

My suggestion is to read the instructions--something that can be hard for us guys: you won't regret it (assuming you follow the instructions!)

Sabreman 04-18-2013 11:36 PM

Re: Removing Bottom Paint
 
A friend gave me this great technique.....

I used a 3/4" wood chisel to "peel" 6 layers of paint. It was very fast, sharpening with a diamond sharpener every 20 minutes or so. I used a carbide tipped paint scraper on the keel and rudder. With 2 of us working, it took 8.5 hours. Then I used a 6" (30% more surface area than an 5") random orbit sander attached to a Shop-Vac. I sanded first with 60 grit, then 120 grit, 6 hours total. The shop-vac prevents sandpaper clogging and extends the life of the disk. Replace disks every 5' feet of hull, never try to make sandpaper "last".

Details and photos are in the link. Click the thumbnails for a larger image: Victoria Bottom Stripping & Fairing

DannyboyUpstate 04-19-2013 07:03 AM

Quote:

Originally Posted by fallard (Post 1018360)
My suggestion is to read the instructions--something that can be hard for us guys: you won't regret it (assuming you follow the instructions!)

Haha. Yeah, I'm with you. A young apprentice at my job used to tell a story about when he was in the military and some rebel (excuse the term) and he were teamed up and the guy told him "INSTRUCTIONS?! THAT'S THE FIRST THING IN THE TRASH!!!" So we say that all the time.


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