• From: nyc toronto
  • Registered: 2012-01-04
  • Posts: 163

Topic: VC-17 / Bottomkote XXX anti-fouling paints

I wanted to scrape off my old Bottomkote XXX paint and replace with VC-17.  Unfortunately, Interlux confirmed what I had already been told.  You CANNOT paint over Bottomkote XXX. You have to blast off every trace, an unpleasant and expensive job.  I tried paint remover and sanding.  Both were unpleasant and injurious to my health.  I was coughing up blue paint for an hour afterwards, even though I was wearing a mask.


Hi Oliver,
Unfortunately I am afraid to say, but due to the fact that Bottomkote XXX is such a soft eroding paint, it will make compatibility very very difficult as it essentially will be an unstable base. Based off of the fact that it is such an unstable base, you should not apply VC17 overtop as the movement of the underlying layer will cause splitting/cracking/peeling. Therefore and unfortunately I would recommend that you do not apply VC17 overtop of Bottomkote XXX as such an application will result in a gigantic mess. I would strongly recommend that you remove all traces of Bottomkote XXX from the surface to expose the underlying bare fiberglass surface and then apply VC17. As for any primers, if you are looking to achieve some moisture barrier protection, then yes they will absolutely be beneficial and InterProtect 2000E. However if you aren't interested in adding any moisture barrier protection, then there will be no need for any primer.

I apologize for any inconvenience and hope this helps!

All the best,
Jay Smida
Interlux Yacht Finishes

  • From: Barrie, Ontario, Canada
  • Registered: 2005-10-10
  • Posts: 237

Re: VC-17 / Bottomkote XXX anti-fouling paints

Would a strong power washer take it off?

  • From: nyc toronto
  • Registered: 2012-01-04
  • Posts: 163

Re: VC-17 / Bottomkote XXX anti-fouling paints

Interlux and the local boat yard independently told me I'd need to hire a "salt blaster" at a cost of about $600. I would also require an environmental tent to keep the noxious powder under control, and a full environmental suit and mask. These anti-fouling paints are truly toxic.

And then, once I removed every last trace of Bottomkote XXX, I should apply two coats of Interlux 2000 primer and three costs of VC-17. After the first year, I could just wash down with detergent and water and apply one coat of VC-17.

Then you're good for a one coat of VC-17 a year for the next 20 or so years. What bliss!

4 Reply by Ian Malcolm (edited by Ian Malcolm 2012-11-23 20:34:20)

  • Registered: 2006-09-20
  • Posts: 175

Re: VC-17 / Bottomkote XXX anti-fouling paints

You'd be amazed how fast you can scrape erodable antifouling, but it needs to be kept slightly damp (not wet) to control dust. Hose down often over a day or so if the boat has been out a while as you want the paint to be softer not rock hard.   Mist a strip ahead of where you are working with a hand sprayer while you are taking a break from scraping every few minutes.  Clear a small patch down to the gelcoat then work out, trying to get a straightish edge and if it gets tough reduce the with of cut you take.   

Narrower blades work better than wider ones as you can keep enough pressure on more easily and the hull isn't flat.  Even with a 1" carbide hand scraper you can clear a square foot back to reasonably clean gelcoat in a few minutes. A 1/2" one is actually faster!   

You do have to take it easy at first till you have the got the feel of it to avoid gouging so don't start out with a power scraper at full speed!   Usual PPE required.

The yard wont consider it because it requires a lot of care and attention and is rather labour-intensive, not to mention muscle-building. Not economic for them.
It may not be economic for you - depending on your earning power as an hourly rate, the value of your free time and the cost of extra time on the hard if you only work at it weekends. (Believe me - you will regret doing both sides the same weekend unless you are fitter and tougher than 99% of the population. Better to set a target of a few meters, take a break add do another job, then come back to it.)

Because most of the paint will come off as small flakes or granules, you shouldn't have a major dust control problem.  Tarping under the boat and sweeping up for toxic waste disposal should be sufficient if there isn't too much wind.

I suggest getting a small hand scraper (but not a cheap one) that uses replacable blades and trying a patch.  If it goes reasonably well consider a power scraper.