Question on bottom paint/paint blisters

JohnV8r · Post by **JohnV8r** » Sep 3rd, '06, 23:18

Hey Guys,

I had Shambala out of the water to have the rudder ports pulled and refurbished recently. While she was out of the water, I noticed there were a lot of silver dollar sized paint blisters (where the paint was not adhering because of the build up of previous layers of paint). There were no osmotic blisters.

The guy at the boatyard suggested that I pay $4000 to have the paint stripped off the bottom and a new epoxy barrier coat and bottom paint applied.

Shambala has an epoxy undercoat that was done before I began my stewardship. There is a lot of paint build up on the bottom, but there is no reason for me to think the epoxy barrier coat needs to be stripped and replaced. My questions are as follows:

1. Is there any reason why I couldn't sand the old bottom paint down to the epoxy barrier coat myself? If so, is this just a case of time, elbow grease, and a sander or is there a more efficient way to accomplish this?

2. Is there a point at which the epoxy barrier coat really does NEED to be replaced and if so, what are the warning signs.

Again, Shambala has NO osmotic blisters and I'm just wondering what the sense of urgency for shelling out $4000 to strip and reapply an epoxy barrier coat really should be.

Thanks in advance.

pfinx · Post by **pfinx** » Sep 4th, '06, 07:07

I have a B28 73. I had what I thought was the same problem. Multiple layers of bottom paint that needed to come off. The previous owner had barely scraped the bottom. I was working on another boat trying to get bottom paint off to the gel coat. I spent all summer on it and finally drug the boat to my friendly boat yard where they sand blasted it off. If done properly they should be able to sand blast to the barrier coat. They may chip some barrier coat but you could reapply.

However, if someone claimed that they stripped the bottom and put on barrier coat then this has been done recently. You shouldn't have any paint blistering.

So you can get yourself a grinder and hit the areas and see if there is a barrier coat underneathor you can remove all of it with sandblasting.

Capt Dick Dean · Post by **Capt Dick Dean** » Sep 4th, '06, 08:41

I sand blasted my 31 two yrs ago. Cost was $12.US per foot. I hung the side curtains and the bottom tarp myself. After the sand blaster man got his gear on and filled up the sand tank, it took 1 hour 15 minutes to clear the bottom. He told me the bottom did not have to be filled in with epoxy since it was very good(1972 Bahia Mar). The time of the yr was October in New Yoek.The hull dried out for 6 months. It took longer becaues of the cold weather. I put on three coats of barrier, then painted the bottom with ablative paint. Boat speed pick up with a very nice bottom.

Your boat yard thinks poorly of you or they are robbers.

After you remove the bottom paint, let the hull dry out! Then barrier coat.

chris walter · Post by **chris walter** » Sep 4th, '06, 09:21

John, don't assume that your barrier coats were done properly or at all, unless you saw it your self. I have the paperwork for the barrier coats from my previous owner and last yaer when I was hauled out blisters were everywhere. When the hull was stripped there was no barrier coat.
Be cautious now to avoid a major problem later. $4000.00 is high. My labor bill for the blister job was $5000.00 complete. Chris

JohnV8r · Post by **JohnV8r** » Sep 4th, '06, 11:47

I'm in California where we are in the water year round, so I don't really have the luxury of coming out of the water for an extended period without getting double dipped on the cost of my slip and lay days at the yard.

I do have an epoxy barrier coat as I have seen it myself.

The natural point at which I'll strip the entire bottom off (if that is my only recourse) would be when I repower. It finally appears that it is realistic to expect that I will repower sometime in the next 10-12 months. That would give me the ability to let the hull sit for a few months. The $4000 is likely impacted by the fact that yard labor is $90-$95 per hour here in Northern CA.

The real question for me is should I have the yard simply sand, prep, and paint as usual or attempt to do something more aggressive to resolve the potential for paint blisters moving forward.

In Memory Walter K · Post by **In Memory Walter K** » Sep 4th, '06, 11:54

It would seem to me that once sanded and prepped, the barrier coat should do that. Walter

Rawleigh · Post by **Rawleigh** » Sep 4th, '06, 16:57

John: I stripped mine myself last year. It wasn't that bad a job. I have since tried a new stripper that is very easy to use. You spray it on and in 15 minutes the paint is bubbled off. http://www.por15.com/PRODUCTS/ACCESSORI ... fault.aspx
I was going to re-barrier coat mine, but decided against it after stripping. I primed it and put on two coats of Ultima SR ablative bottom paint. I have not hauled out this year and the bottom is in good shape (with the exception of the hardware, as usual).

JohnV8r · Post by **JohnV8r** » Sep 4th, '06, 19:32

Rawleigh,

Thanks so much. That is exactly the kind of solution I was looking for.

John

R Cahoon · Post by **R Cahoon** » Sep 5th, '06, 14:33

Most barrier coat companies say four or five coats. Also every ounce of bottom paint must be removed for proper adhesion.
There are many products to strip bottoms with out disterbing the barrier coating. I used a water base stripper, you can roll it on but spraying on is best for getting a heavier coating. Per the instructions I waited four hours then took a wide paint scraper and it came off in sheets in about 30 minutes. Then a quick DA sander job to get the little residue left. I barrier coated with four coats.
If I was stripping a bottom that had been prior barrier coated I think I would touch up any disterbed areas and then put a preventive coat on.

Keep Smilin

Tony Meola · Post by **Tony Meola** » Sep 5th, '06, 20:47

John

See if you the yard has anyone that will use baking soda instead of sand. They say that the baking soda can be controlled so the barrier coat doesn't come off. How long does the barrior coat last, well to give you an idea, we put 5 coats on in 1986 and it is still going strong. Tony Meola

Rawleigh · Post by **Rawleigh** » Sep 5th, '06, 23:08

The yard I use won't let you soda blast because of the corrosive effect it has on the aluminum and other parts on the other boats around the yard. The dust cloud travels pretty far, and if the other oats aren't washed off thoroughly it can cause big problems.

Rawleigh · Post by **Rawleigh** » Sep 5th, '06, 23:08

The yard I use won't let you soda blast because of the corrosive effect it has on the aluminum and other parts on the other boats around the yard. The dust cloud travels pretty far, and if the other oats aren't washed off thoroughly it can cause big problems.

Kingfish · Post by **Kingfish** » Sep 6th, '06, 19:54

I've seen here in SoCal the use of ground up Wanut shells used as a stripper in place of sand. (Now I'm talking cars) Sand is brutal on sheet metal where as the Walnut media is not.

Why wouldn't it work on a boat?

CaptPatrick · Post by **CaptPatrick** » Sep 6th, '06, 20:29

Jim,

Sand is just as brutal, if not more so, on fiberglass too... Sand warps metal, it breaks the fibers in fiberglass.

Walnut shell blasting works well on fiberglass. Walnut shell & baking soda are the two prefered media types.

Br,

Patrick

bertram31.com

Question on bottom paint/paint blisters

Question on bottom paint/paint blisters

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