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post #11 of 21 Old 05-08-2012
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Re: Yet another bottom paint question, now featuring picture

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Originally Posted by Minnewaska View Post
The OP is witnessing, first hand, the danger of apply one paint over another.
I disagree. What he is witnessing is poor preparation of the existing paint prior to overpainting. The paint in this spot has simply disbonded from the undercoat. If the two paints were incompatible with each other, the problem would involve the entire hull and would have happened immediately.

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They are often incompatible with each other.
In reality, they are sometimes incompatible with each other. Most commonly used, copper-based anti fouling paints (regardless of whether they are hard or ablative) are completely compatible with each other. That being said, vinyl and teflon paints (VC 17, Baltoplate etc.) and the growing number of zinc-based paints cannot be used with anything except like products. But it does not appear to me from the OP's picture that that is the case here.

Last edited by Fstbttms; 05-08-2012 at 01:07 PM.
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post #12 of 21 Old 05-08-2012
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Re: Yet another bottom paint question, now featuring picture

To me, this is not a questoin of "if" but rather "when". At some point, especially if you question the actions taken by previous owners, it may be a good idea to strip it and take a look for problems. Understandably, it is expensive and time consuming to undertake a project like this. If you believe the paint left is well adhered then feathering and painting may be all that is needed. But if you think the paint is loose, or loose between lower layers then the future becomes a little more bleak. This decision is easier for me since my boats are small. It all comes down to making sure the glass is protected. So, I'll stop short of giving you "unqualified" advice, and simply say good luck. Joe
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post #13 of 21 Old 05-08-2012
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Re: Yet another bottom paint question, now featuring picture

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Originally Posted by Fstbttms View Post
......In reality, they are sometimes incompatible with each other......
I guess we are going to split hairs between sometimes and often. Here is what Petit has to say.

http://www.pettitpaint.com/fileshare...patibility.pdf

The big problem with used boat buyers, is they rarely seem to know for sure what is on there now. In this OP's case, it seems they need to know both coats.

I would start over and do it right.


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post #14 of 21 Old 05-08-2012
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Re: Yet another bottom paint question, now featuring picture

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Originally Posted by scratchee View Post
Eventually, maybe next season, I'll probably want to have the hull stripped using something caustic, carcinogenic, and deadly to the surrounding wildlife and my beloved Bay.

To me it does not look like you got a lot of paint build up. Looks like gel coat then a blue bottom paint then the black. If the rest of the black is holding well, I would just light sand where the black came off and reapply the black paint- try to find out what was used and use that.

My boat has probably 10 layers of bottom paint. I do need to strip them, maybe next hull out. But after two years my last bottom coat is still holding up well.

I am looking into maybe a soda blast to remove the 10 layers of bottom paint.

One thing those pressure washers can strip even a well bonded paint off a surface- too much pressure, holding nozzel to close to work, holding nozzel for two long- pressure washers can eat into concrete if you want to.

Last edited by casey1999; 05-08-2012 at 04:29 PM.
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post #15 of 21 Old 05-08-2012
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Aqua guard is water based and wears well but can't be put on over VC17 which I have Drat!!
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post #16 of 21 Old 05-08-2012 Thread Starter
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Re: Yet another bottom paint question, now featuring picture

Thanks everybody for the great information and advice. I do have more information that I didn't include in my original post, so all told I'm leaning toward just smoothing the edges and re-coating for this season.

- I bought the boat from the second owner, who had it for 28 years. Judging from the notes, receipts, and logs he gave me, he kept up very well with routine and periodic maintenance. He told me he put two coats on every other year, and never had any problems with the hull or paint. I'm guessing he did the same thing I'm considering (smoothing and re-coating chips,) which, while not ideal, did not cause him any problems in that 28 years.

- He used Pettit Hydrocoat, and I bought the same thing to avoid compatibility issues.

- For the most part, the current bottom paint does seem sound and well adhered. I plan to go over it well and find any other unstable areas.

I do agree that stripping the hull (soda blasting sounds enticing) would be the best way to go about this, and I'm not afraid of doing that at the right time. But right now, with a new boat at the beginning of the season (and before it gets too hot,) I'd like to focus on cleaning and sailing! So as long as the hull is as well protected as it was for the prior owner, I think I feel safe waiting until this fall or next spring to take it down to the gelcoat and start from scratch.

Many thanks again for the replies. Feel free to chime back in, as I'm learning a lot.
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post #17 of 21 Old 05-08-2012 Thread Starter
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Re: Yet another bottom paint question, now featuring picture

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Originally Posted by casey1999 View Post
To me it does not look like you got a lot of paint build up.
You may be right, but it seems like a lot of buildup to me because Pettit says a dry layer should be 1.5 mils thick. That means two dry layers should be as thick as the 3 mil plastic sheeting I have in my basement, when actually it is far thicker. It's as thick as two or three playing cards stacked on top of each other.
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post #18 of 21 Old 05-08-2012
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Re: Yet another bottom paint question, now featuring picture

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Originally Posted by scratchee View Post
You may be right, but it seems like a lot of buildup to me because Pettit says a dry layer should be 1.5 mils thick. That means two dry layers should be as thick as the 3 mil plastic sheeting I have in my basement, when actually it is far thicker. It's as thick as two or three playing cards stacked on top of each other.
Is Pettit refering to how thick you should put the paint on? If the existing paint on your hull is 3 playing cards I would not worry about that. My old hull paint is probably 1/16 inch in places. I spent two days sanding with 80 grit (thickness started at probably 1/8 inch) and was running out of time so I went ahead and bottom painted. Acually a thick layer of new bottom paint is recommended at the water line and leading edges as this is where it will foul and wear away faster. Soft bottom paint is made to wear off the hull over its life.

I think you are good to go. As you say just look for any real loose paint (don't go over board or you will remove good paint) sand and recoat. See how it looks in a year and change plan of attack if needed. Maybe have PO look at it, he seems to have taken good care of her.
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post #19 of 21 Old 05-08-2012
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Re: Yet another bottom paint question, now featuring picture

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Originally Posted by scratchee View Post
I do agree that stripping the hull (soda blasting sounds enticing) would be the best way to go about this, and I'm not afraid of doing that at the right time.


I do not think you need a soda blast. I was considering it (still am) because I spent two days trying to sand off old bottom paint (the pro painter at the yard said my boat has paint sickness) and still only got half the paint off. I was going thru a bunch of 80 grit sanding disc with commercial orbital sander and still could not get it all off. The problem I had is the sanding disc kept getting clog.

I think you best be is to get the boat in the water and sail. Your hull actually looks good. You do not want to create problems for yourself by soda blasting at this point and maybe never. A poor soda blast could damage your hull.

Last edited by Faster; 05-08-2012 at 08:24 PM. Reason: fixed quote
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post #20 of 21 Old 05-09-2012
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Re: Yet another bottom paint question, now featuring picture

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Originally Posted by LessTacksing View Post
According to the newspaper it is supposed to be "environmentally friendly"

"A small chemical company owned by an amateur competitive sailor is making its bid for a share of the $4 billion global market for marine coatings with an environmentally friendly alternative that also saves energy by reducing friction between the hull and the water." From the Timesunion.

David
Calling that stuff "environmentally friendly" implies that existing paints aren't. There isn't a scrap of evidence that hard, low leaching, copper paints are harming the environment. If they did have affects away from the boat, how come the neglected boat next to mine is covered in a veritable forest of growth?

The science is basically this : The paint has copper in it. Copper is bad. The paint is bad.

Bristol 31.1, San Francisco Bay
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