MacGregorSailors.com

Timmay wrote:

Divecoz wrote:OK Timmay....... Is it Yellow lake scum or yellow barrier paint? That question is causing a difference in opinion on what to do .

Nah, thats yellow barrier coat. The white/grey areas are where it has worn off. Timmay!!!

So where is the Anti-fouling paint? Why would someone go to the trouble of putting on a barrier coat and then not do the anti-fouling?
I have seen anti-fouling done without the barrier coat though.
The antifouling comes in a wider variety of colors whereas epoxy barrier coats may come in only a few colors so that one can paint using two colors, a first coat one color, then see where the second coat covers the first. I have not seen yellow barrier coats before but I have seen yellow anti-fouling. (red, blue, & black too).
I just did my 4 layer epoxy barrier coat last spring (grey color) using a foam roller to keep it smooth and I still got a slight orange peel texture. Then I put a royal blue anti-fouling over that with a foam roller and it did not come out smooth as glass but smooth enough for what anti-fouling is.
I am not convinced it is a barrier coat....

Terry,
I am new to this stuff and can only go by what the PO has told me. Perhaps I misunderstood and the yellow is antifouling and the greyish underneath is barrier. Not sure. I just know it looks bad, is coming off, and it is very rough. I would like to get it down to the gel and then redo everything. I just want it to be right and I know if I do it, it will be done right. Thanks for your input. Timmay!!!

Timmay wrote:

Divecoz wrote:OK Timmay....... Is it Yellow lake scum or yellow barrier paint? That question is causing a difference in opinion on what to do .

Nah, thats yellow barrier coat. The white/grey areas are where it has worn off. Timmay!!!

Oh, that's some ugly barrier coat IMO. It looks like lake slime (what mine looked like this week when I pulled it out).
Then it should be easy. Sand the junk off until you see white or it's smooth and put another coat on.

For me, I left my bottom bare gelcoat with a coat of Aurora bottom wax this year. It worked pretty good. Slime just power washed off.
If I was gonna use a yellow barrier coat, I'd top it off with a nice bottom paint.

--Russ

From your description, you have a gray barrier coat and the yellow is anti-fouling, which wears off with time. With proper prep, you should be able to save the barrier coat and just update the anti-fouling. The West Marine Blog has an excellent section on the process.

~Rich

Done

I guess we need more clarification. From his description, I get that the yellow coat is on top of a gray coating. If it is just the yellow that is deteriorating and exposing the gray, then it just needs smoothing out an reapplication of anti-fouling. If the gray is coming off and exposing white gel coat, then more extensive stripping will be needed.

~Rich

[Done with Hamin and this board

Sorry, mates - I've been away from the board since Friday on a Boy Scout hike / camping trip (and then at work Monday, but still recovering!)

Having said that, I've now read through this thread and I can't really see if you've sussed out whether it's barrier or anti-fouling coating, nor what the coating is under it, nor whether it is epoxy or some other product. I'd also like to see a very close-up picture of the actual 'wear' areas... is it wearing off, or truly delaminating?

As far as solvents go, however, there's several choices besides just sanding it all off, and they won't harm the gel coat... for example, Interlux makes a very good bottom stripper, "Interstrip 299E", and it will get the big bits, but should be followed with their thinner product, "Interstrip 399", to get the rest. I've used this system before and it works well, although it's a little expensive.

"Peel Away Marine Safety Strip" is another bottom-stripper product, and seems similar to the Interlux in performance. I have never used this particular product, but it's highly rated by a number of marine sites, so I'm assuming it does the job. They recommend you use it with their special "stripper paper" for best results.

As with any stripper, work in small patches, do it in the cool shade, and never leave the stuff on there longer than a few hours. Wear skin and eye protection at all times, clean up thoroughly and safely discard any waste.

Then, before you re-paint, I strongly suggest using Interlux Fiberglass Solvent Wash 202 on a fine bronze-wool pad - rub it in thoroughly to remove any contaminants, and check your success by running water over the surface... if it sheets off, you're OK... if not (and the water beads up or diverts away from specific areas), then re-apply the 202 until it sheets cleanly.

Now, if you do choose to sand it off instead, I'd definitely do it wet (for safety and air quality reasons), starting with a coarse cut (220) to get the majority off, then drop back to a 400 once you get to a thin remaining coating. I would not try to make it ultra smooth (by using a 600 or 1000+ grit) because you want that bit of roughness to key the new paint onto. You can get an air-powered line sander that will work pretty good in wet conditions (to speed the job), but as with any power tool it's pretty easy to cut too fast, so use with caution. And again, finally wash it with 202 before painting.

Dimples on golf balls make the flow turbulent, which results in less air resistance.

The dynamics of water on hull surface are in a different regime than a golf ball through air (Im guessing a typical golf ball velocity is about 50 m/s vs our hull speeds of 3 m/s (blue) and 6 m/s (white)

You wont see any difference unless you are a serious racer squeaking out every bit of performance.

My SWAG is that resistance from growth and barnacles will be larger than surface skin effects at boat speeds.

I know a retired flow dynamics prof who can clarify this in gory detail, if you really want. Probably cooks all his meals in Reynolds wrap....and makes a Froudian slip or two once in a while

[Done with this board

Being new to antifouling myself, what is the difference between antifouling and barrier coat?

Glenn

Basically, a barrier coat protects the gelcoat from osmosis and the formation of blisters. An anti-fouling coating is a coating that retarded the formation and eases the removal of unwanted growth on the hull. The former is usually a tough layer of epoxy, or some other hard material. the latter is usually a chemical coating and is considered ablative, or sacrificial, needing annual replenishment.

~Rich

So if I remove the antiflowing that is in need of removing or replacing, I then need to put on a barrier coating .... as we keep Imagine on the trailer when we're not out sailing is that still the case?

Glenn

Glenn,

I think that many Mac users that primarily trailer and don't leave their boats in the water for long stretches of time do not use a barrier coat nor an anti-fouling paint. Many just use a wax.

But if you leave your boat in the water for a long time you may want to consider a barrier coat to prevent the osmosis blisters and an anti-fouling to help prevent the growth of barnacles or other growth.

I have a barrier coat (4 coats of Epoxy with the orange peel texture) put on by the previous owner. For the first year I thought it was an anti-fouling paint until I left the boat in the water for 8 weeks and had a pretty impressive barnacle growth.



If I ever move to a location where I can use a slip I will probably put on a anti-fouling paint on top of my epoxy. I don't think I need to do anything to the hard epoxy I got now...hopefully it will be good for a long time. But anti-fouling needs to be redone every so often...I think the frequency depends on the brand.

Hope that answers your question.

Cheers,
Jim

All I have to do is get the old anti fowling off, anyone ever use Dilunett solvent free paint remover, they recon it's gel coat friendly.

Glenn