how much to bottom paint /epoxiy to remove

[groundtackle]

Hi there
looking for some advice
I purchased my boat in Mexico. I was told it had been stripped and had epoxy barrier and new anti-fouling applied in 2011. At the survey we found a few superficial blisters and the yard there (in Mexico) repaired them.
I was not too concerned because there were not many and they were all superficial (most seemed to be just under paint and there were no areas that involved the actual layup.
I now have the boat in Wa and I was going to have the bottom services and new anti-fouling applied. After recommending and completing a "heavy sanding" the yard now says that the job done in Mexico involved putting epoxy on top of old anti-fouling and is recommending a much bigger job (still waiting for a quote. ) The sent some photos of the bottom to justify their recommendation. I am not sure if they have it right or could they be mistaken. Can anyone comment on these photos and on how I should proceed?(note the labeling was done by the repair yard not by me)
thanks
Nick

[groundtackle]

I am referring to the original job in Mexico done in 2011. Please open the pdf file...it is a photo of the bottom as it is now with labels on the various layer as reported by the yard in Wa that is currently working on the boat for me.
thanks
Nick

[minaret]

Which yard?

[groundtackle]

North Harbour Deisel.- Anacortes

[minaret]

Not familiar enough with them to trust their opinion or not. That does look pretty suspect though. Sure it's not alternating colors of barrier coat? Is there an adhesion problem? Have you done the usual adhesion test?

[groundtackle]

Originally Posted by minaret

Not familiar enough with them to trust their opinion or not. That does look pretty suspect though. Sure it's not alternating colors of barrier coat? Is there an adhesion problem? Have you done the usual adhesion test?

What is the "usual adhesion test" and how do I do it?
How can I tell if each layer is different colors of barrier coat vs anti fouling layers?

[groundtackle]

How do I do a "standard adhesion test" and how can I determine if these are different colonies of barrier epoxy vs old layers of anti fouling?

[minaret]

Originally Posted by nshawdvm

How do I do a "standard adhesion test" and how can I determine if these are different colonies of barrier epoxy vs old layers of anti fouling?

If this is really barrier coat which has been applied over bottom paint, then the adhesion between the barrier and bottom paint will very likely be poor. There are all sorts of adhesion testing kits and special tapes and the like, but basically, to see if you have an adhesion problem on bottom paint, you can do a simple tape test. Use Gorilla tape or similar and apply a 1' x 1' patch to your bottom. Really rub it on until its stuck very good (a light solvent wipe first may help). Then use a utility knife with a fresh razor to cut an X into the square of tape. Cut through the bottom paint and barrier coat but not through the gel if possible. Then start a corner of the tape and pull it off aggresively. If any paint flakes off on the egde of your X cut you have an adhesion problem. If not you probably don't (right now). This is (obviously) a destructive test, and you will have to fix the razor score afterwards. It is quite common.

If you have no adhesion problem, I would question what they are telling you. You should also carefully inspect the bottom yourself. The differences between most bottom paints and barrier coat are quite obvious. Bottom paint is generally much softer than barrier coat. Obviously there are exceptions to these generalities, like very hard racing paints which are meant to be burnished, or relatively soft barrier coats, like Duratec vinylester. Get a second opinion before dropping a ton of dough.

[Jon Hacking]

Applying an epoxy barrier coat on top of antifouling is just plain stupid. The Mexican boatyard was being lazy/inept. Antifouling is soft & made to come off. A barrier coat should always be applied directly to the substrate (usually gelcoat) & antifouling applied on top.

Having said that, if the antifouling underneath is hard, the epoxy *may* last a few seasons. But to do the job right, the antifouling (& the covering epoxy) should be removed & new epoxy applied once the bare hull is prepared.

[wingless]

The photo evidence shows the bottom was painted wrong.

It is a lot of work to properly remove the epoxy and anti-fouling, but those are the correct steps.

[groundtackle]

Ok thanks everyone
Is there any way to tell for sure if any given layer is a hard anti-fouling paint vs a barrier epoxy ?

[minaret]

Originally Posted by nshawdvm

Ok thanks everyone
Is there any way to tell for sure if any given layer is a hard anti-fouling paint vs a barrier epoxy ?

No. Just experience. If they want to strip it back to glass and try to charge you a fortune to do so, I can give you a number for a roving peeler guy who's excellent and will peel your bottom in one day for relatively cheap.

[AtlanticGreenPro]

Originally Posted by nshawdvm

Ok thanks everyone
Is there any way to tell for sure if any given layer is a hard anti-fouling paint vs a barrier epoxy ?

nshawdvm, if you found a few superficial blisters I wouldn't be that concerned, especially if the marine surveyor didn't red flag them... One question is how old is the boat and who's the manufacture would also be helpful?

But based on my experience and looking at the three photos as well as the PDF you attached..... I'm seeing two different things and without actually being there the 3 photos are a little confusion on just what layer I'm looking at.

But based on BELOW image of the PDF my first reaction is that you have 5 alternating layers of barrier (GRAY & WHITE Interlux 2000E barrier epoxy.) Which is what Interlux recommends.



The layer marked 6th PRIMER is actually the 1st coat of white epoxy barrier coat (Maybe Interlux 2000E WHITE)

The layer marked 5th BOTTOM PAINT is actually the 2nd coat of gray epoxy barrier coat (Interlux 2000E GRAY)

The layer marked 4th EPOXY is actually the 3rd coat of white epoxy barrier coat (Interlux 2000E WHITE)

The layer marked 3rd BOTTOM PAINT is actually the 4th coat of gray epoxy barrier coat (Interlux 2000E GRAY)

The layer marked 2nd EPOXY is actually the 5th coat of white epoxy barrier coat (Interlux 2000E WHITE)

And the layer marked TOP LAYER BOTTOM PAINT is two coats of bottom paint.

Personally I'd check the invoice from the marina on when the boat was painted and see if they did 5 layers of barrier coat.... But my gut reaction from taking bottom paint off of gel-coat is that you have 5 layers of barrier coat and if it was me I'd just put another coat of ablative over what you have there.

Hope that helps.

[Suijin]

It's impossible to tell what is going on from the PDF photo in terms of layering. At this point, the only one who could tell you is the guy that sanded it down as he was observing the layers being revealed as he was working.

Looking at the photos in your original post, it looks like grey barrier over gelcoat with blue/green anti-fouling on top of that. Looks like the yard in Mexico did not fill all the blisters after opening them but simply painted over with bottom paint. It also looks like the WA yard's aggressive sanding went right through the barrier to the gel. But that's just a guesstimate based on what's visible and to Minaret's point, it's a crap shoot trying to figure out what's going on without an in-person inspection.

How to proceed is a function of how much you want to spend vs. the longevity/soundness of the solution. At one end of the spectrum you could take the whole hull down to the gel, fix the blisters properly, barrier coat the whole thing and repaint. At the other end you could just clean out the blisters, fill, barrier coat them, then repaint. If it were my boat and I hauled it every year for the winter, I would probably go with the simplest solution and then if I had a problem develop later on, contemplate a full-on hull refurbishing.

As Minaret said, it all comes down to adhesion. It also comes down to water penetration if the barrier coat is gone in certain areas, but that's not the end of the world depending on how you use your boat.

[AtlanticGreenPro]

Originally Posted by Suijin

It's impossible to tell what is going on from the PDF photo in terms of layering. At this point, the only one who could tell you is the guy that sanded it down as he was observing the layers being revealed as he was working.

Suijin, I'm just speaking from experience... we take bottom paint off of boat bottoms... sometime just the anti-foul leaving the barrier coat intact and other times we take both the barrier coat and anti-foul off right down to the gel-coat.

Looking at that PDF he has 5 coats of alternating barrier paint epoxy (Gray and White)... most likely Interlux 2000E and two coats of anti-foul.

Also Interlux advises alternating barrier coat paint between white and gray so you know you're getting full coverage per coat.... that how we do our barrier coats now.

Again... just speaking from experience.