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Catalina/Capri 25/250 Sailor's Forums

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VC-17 Over Ablative Paint

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Bruce Baker
Captain

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USA
402 Posts

Initially Posted - 03/24/2005 : 13:38:25

I've got Petit Horizon paint on my boat now, and I want to repaint with teflon paint, VC-17. The Interlux site says that removal of all paint is desirable, but says you can sand "conventionl" antifouling paint and paint over it. Is ablative paint "conventional"? I plan to sand off as much as I can, but what happens if there's a spot of the old paint under the VC-17? Does it stick, or is it one of those oil and water kinds of things?

Also, when I'm sanding along and most of the paint is gone, do I need to worry about sanding the bottom of my boat off. Is there some extra gel there as a safety margin?

Thanks,

Bruce Baker
Falls Church, VA
"Yee Ha" 3573
'83SR/SK

Edited by - on

dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/24/2005 : 14:36:13

Bruce,

According to the [url="http://www.yachtpaint.com/USA/boat_painting_guide/pdf/antifouling/compat.pdf"]Antifouling Compatibility Chart at Interlux[/url], ablative paints must be removed before applying VC17m.

When I purchased my boat a few years ago, the bottom was a complete mess. It appeared that the PO experimented with various incompatible paints over the years and turned the heavily coated bottom into what looked like the surface of the moon. It was so bad that it made a gravel road look baby-butt smooth.

Anyway, I stripped off the old, deteriorating mishmash of bottom paint, applied an epoxy barrier coat, then topped it off with VC17m. It was a lot of blood, sweat, and tears

, but the results were worth it.

If you want to reap the benefits of a fast, Teflon paint like VC17m, then proper prep work is essential to getting that smooth, slick surface.

Good luck.

Edited by - on

Gloss
Master Marine Consultant

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USA
1916 Posts

Response Posted - 03/24/2005 : 15:12:22

If I was a wise ass I would say:

Sure, you can paint over an ablative paint. Just don't expect it to stay on.

But everyone here knows that I'm not a wise ass.

But seriously, Don is correct. You must remove all of the paint first. If I may add this: Surface prep is the single most important step in any kind of a coating job, whether it is your boat, your house, whatever.
See the interlux website and you will get step by step instructions.
painting a boat bottom is both a huge expense in materials, and time. Why blow it if you don't prep the surface correctly? Also, make sure you are in the correct temperature and humidity environment too. Epoxies are very unforgiving in damp or high humidity environments.
Good luck.

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seastream
Navigator

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USA
242 Posts

Response Posted - 03/24/2005 : 17:41:35

Remember that ablative paints work by wearing away. Given that definition, any other paint applied on top of it wouldn't last long.

Bob

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John Mason
Admiral

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USA
687 Posts

Response Posted - 03/25/2005 : 12:47:33

Don't sand the gel coat off. If you were putting on an epoxy barrier coat, sanding a bit of the gel coat wouldn't hurt things.

Listen to Don and Frank - Surface prep is the MOST important step. Do it right and no worries.

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aeckhart
Master Marine Consultant

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USA
1709 Posts

Response Posted - 03/25/2005 : 20:42:22

Interlux recommends putting a coat or two of VC-Tar - an undercoat, on the hull first. It's their barrier coat. VC-17 will not stick without it.

Al
GALLIVANT #5801

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Steve Milby
Past Commodore

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USA
5909 Posts

Response Posted - 03/26/2005 : 07:00:58

I never sand old bottom paint down to bare fiberglass. It's much safer, and easier, to use a chemical stripper that is specifically designed to remove paint from fiberglass. After all the paint has been removed, I hand sand the entire bottom very lightly, just to scuff it up enough to help the new paint bond to it. Old paint can also be blasted off safely, but not using sand. I don't recall what is considered the safest method of blasting. I think blasting with crushed walnut shells is generally considered safe, but someone else can tell you about that.

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Gloss
Master Marine Consultant

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USA
1916 Posts

Response Posted - 03/26/2005 : 07:41:05

and after you sand, or chemically strip your bottom (sounds rough, doesn't it) you must clean it thoroughly, removing all residue of dust or chemicals. Also use whatever solvent the manufacturer recommends for cleaning.

Do not skip any step the manufacturer recommends.

Interlux puts out a great booklet on procedures, in addition to having great info for download on their site. I have also seen good info from Petit too, if that's the route you decide to go.

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dlucier
Master Marine Consultant

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Virgin Islands (United Kingdom)
7583 Posts

Response Posted - 03/26/2005 : 14:09:07

Bruce,

Do you know if your boat already has an epoxy barrier coat under the antifoulant paint?

If it does, this may have an impact on whether you sand, grind, scrape, or chemically remove the old bottom.

Just a thought.

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Notice: The advice given on this site is based upon individual or quoted experience, yours may differ.
The Officers, Staff and members of this site only provide information based upon the concept that anyone utilizing this information does so at their own risk and holds harmless all contributors to this site.