Unintended project...argh.

[Dug]

I went down to the boat yesterday intent on prepping the bottom for paint. Usually I hit the loose spots with a chisel, knock off the loose paint, and then fair it with the sander, and roughly sand the bottom. It takes about 2-3 hours total.

This year the chisel knocked off more than I expected. And now I have a project on my hands...

About half the paint on the starbord side of the boat bottom is now gone...

I was not planning to get into this, but don't have much choice. It just came off.

Do I need to barrier coat in order to paint and have the paint adhere?

I am not looking forward to finishing this...argh.

[Carl]

When I stripped the bottom of my boat several years ago, under similar circumstances, I thought long and hard about doing a barrier coat. What I finally decided was to fill all the gouges and imperfections with an interlux recommended two part epoxy, prime with the interlux recommeded primer (which basically gets wiped on in no time) and then paint with Interlux premium ablative paint.

My thought the hull was almost 40 years old without a blister, figured it would be good for another 40 years. If I had found blisters or areas that seemed less then adequate I would have went with sealling the bottom.

Just my .02

Carl

One thing if you have the bottom blasted instead of careful scraping or chemically removing the old paint I think you pretty much have to barrier coat. Although some say the soda blast is marginal and dry ice blast would be fine but that process has been real pricey by me.

[wmachovina]

Well when I started the project the blisters were hidden by too much paint,as I looked more it was grim so I had the bottom peeled, the right guy the right tool took one day. filled the gouges with mat,and resin if big enough, then two barrier coats,then paint. Not fun not cheap but done.

[Mikey]

Dug,
Agree with Carl on the forty-year-old hull. When Dreamsicle was ready for launch I went through the same thing. Decided that since it had made it this long without blisters and I was diligent in my stewardship I didn't need it. Also, living on MA. you probably haul for months so you have a significant drying period.
More to the point is why just the starboard side? Is this the side where you started and haven't gotten to the port side? O.K. If, however, this side had a significant paint loss compared with the port, why? Did you have a large buildup? Was it our old friend electrolysis?
Sand the crap out of that bare part, wipe down as directed and paint.
Hell, in MA. you're season's not long enough to accumulate that much stuff. Now if you were in the Keys or Puerto Rico . . .I'd come visit you to look at your problem. Actually, we are about to have the first thunder storm of the season here in VA, got to shut down.

[wmachovina]

btw does anyone know what year layups were more prone to blisters, my 73 was bad but had been in the water in s fla for years, Bill

[STeveZ]

I posed a similar question last spring. At that time the boat yard handled it and it think they just slapped on a new coat of paint. The result in the fall was a similar looking hull (patches missing down to the barrier coat).

I'm faced with the same situation this spring. I'm going to sand the exposed barrier coat, wipe and apply bottom paint to those areas followed by a full bottom coat. If that doesn't work I'll re-apply spot barrier coat next spring.

Here's Capt. Pat's recommendations from last spring.

http://www.bertram31.com/newbb/viewtopi ... 7f57a7bfe7

[Carl]

As to the Barrier Coat, Interlux wants the paint to be a minimum of 10 mils thick, which is more like 4-5 coats brushed or rolled. Maybe other companies require less.

Not that an extra 2-3 coats would be a deal breaker, just have to allow for more time and material

[Dug]

I am less worried about blisters than paint adhesion.

And as for which side of the boat? I am only partway through. I didn't leave myself enough time to do what I have started! Remember, I thought it was going to be a couple hours total. Not so much...

[Charlie J]

dug
slap some paint on her, blast the bottom in the fall and let her dry out next winter, i wouldnt worry about it.

[John F.]

Dug-

I agree with Charlie. Paint it, and get it blasted in the fall. If you've done half of one side in 3 1/2 hours, you still have based on that amount of time about 10 hours to go--and then all the other prep. I'd get it blasted (soda or water?), let it dry out over the winter, and then do whatever (probably barrier coat and bottom paint).

John

[Mikey]

Dug
What they said.

[Pete Fallon]

Bill,
The blistering problem was really bad on the 1973 year boats, 1st oil crisis hit and factory changed in resin suppliers. I've seen 1966, 1968 & 1970 31's with bad blisters, alot has to do with bottom paint prep and how long they were left in the water. 1973 was the worst, did 3 boats of that year and they were all bad.

[Capt Dick Dean]

Three yrs ago I wanted to sand blast the bottom to get all the old paint off. It was Feb and I launch in April. EVERYBODY said it's too late in the season to blast it off. The hull will not dry out. By the way, I'm in New York. The next winter, I came out of the water in Oct and sand blasted off the paint right away. Then it dried out over the winter. Took the guy 1hr 15m. I put the barrier coat on in April.

So at this time in season, I think it's too late. If you want to take it to a bear hull, barrier coat and all.

[Tony Meola]

Dug

Be happy it peeled off. I hate the idea of blasting. Did that once. Probably should do it again but really hate the thought. I would barrier coat though. At this stage whats another weekend and a few hundred dollars more. Then you know its right. Put on an ablative and be done with it.