barrier coat

[Tom Ehmke]

Well, I went and did it. This year I decided to scrape the bottom, sand the bottom, and apply a barrier coat before applying an ablative paint. I have always used a modified epoxy, Petit Trinidad, in the past, but the darned stuff is so hard to scrape off when a few coats build up. So... with my trusty scraper and 10 hours of free time I went to work. Got sick...looked like Papa Smurf when I got done and decided that I really didn't care for the flavor of bottom paint. Oh, yeah, I left my painter's mask at home... Round Two. I sanded the bottom with an orbital sander using 80 grit sandpaper. Used a painter's mask. This time the facial color wasn't as deep, a sort of pastel blue, but I didn't get sick, and didn't eat any dust. So here I am and here's my question. I want to mask and paint the bootstripe, but I roughed the gelcoat up a little bit with the sander trying to get the last little bit of paint off the hull. How do I buff out the gelcoat before I apply the tape and start the barrier coating? I want to do this right, because I don't want to ever scrape again... yeah right.

 

[Justin - O'day Owner's Web]

Do not use compound!

Tom,Do this project right today, and you really won't have to do it again for a very long time. Its worth it in the end.First - I'm assuming you mean you want to mask off the bootstripe then paint below it. If so, you need to wet sand using progressively finer grades of sand paper until the scratches are gone. How deep are the scratches? I would start at about 200 if its bad, 400, if its not, and progress to 1000 or even 1500. Don't rub too hard because you don't want to take off more gelcoat than necessary. You only have so much to work with before you go through it. You want to avoid using compounding products because most of them leave a waxy residue on the hull. You can clean the residue off with wax remover, but if you miss any you will undermine your project by having a failure point in the barrier coat.If you really mean you want to paint the boot stripe, its easier. Go to your favorite marine supplier and pick up some West System or Maas. Mix up some fairing mix, apply it in thin coats and sand fair. Sand smooth up to 400 grit paper. Next, what are you going to barrier coat with? I have had good luck with West Systeming the whole hull, and have friends who swear by the Interlux products. Lastly, good choice to switch to an ablative paint!! No more sanding, scraping, or yearly repaints if you use it correctly. My friend's Peterson is 22 months into its bottom job, has been in the water all that time, and is still looking good.BTW, while you're down there, replace and through-hulls you're not in love with. Maybe unnecessary, but it you do it now its a lot less work, and you know the hull is in perfect condition.This job is a hassle, but you'll be glad you did it.Justin - O'day Owner's Web

 

[Tom Ehmke]

Thanks, Justin

The bootstripe on my O'day is painted blue and I have always taped BELOW the bootstripe with 3/4" tape and bottom-painted below the tape which leaves a nice line between the bottom paint and the bootstripe. The area between the bootstripe and the bottom paint is the area which I sanded with 80 grit sandpaper. I will work the area down with find sandpaper as you recommended, but I still have a few questions about the barrier coat. I have wanted to do this for a couple of years,but I've heard contradicting descriptions of both cost and effectiveness. I decided to go ahead this year, but must admit that I haven't researched this as well as I should have. I'm not sure how many coats I will need to apply to make the barrier truly effective. The cost doesn't seem to be outrageous, but I don't yet know how much I will need to buy. I washed the hull down last weekend and am ready to go. Any other recommendations?

 

[Justin - O'day Owner's Web]

Tom, have you done it yet?

Tom,Sorry to take a long time to answer your post, but finals got all consuming there for a little while.Have you done the barrier coating yet?Justin - O'day Owner's Web

 

[Tom Ehmke]

time is of the essence

Hi Justin,I put two coats on a week ago Sunday. That's all I had time for after washing the bottom, rinsing it, wiping it down with solvent and making sure the barrier coat was going to hold. I also faired the hull in a couple of spots with a stick epoxy. There were some scratches on the underside of the hull at the stern. Because I was unable to get the four coats that I figured would be enough on within the pot time of the paint, I will now have to sand the bottom (again, sigh!) and put the final coats on this weekend, weather permitting. If time permits, I'll put the first coat of ACP on. I chose black and will finish with blue on the final coat(s) Meanwhile... I bought a kit from Island Girl and am in the process of readying the topsides for a final wax with Collinite using the I G products to clean and shine up the gelcoat. Lots of work, and I'm a month behing schedule, but sometimes you just have to go with the flow. Thanks for your interest.Tom