Barrier Coat Advice

[Peter Kozup]

The bottom of my boat will be clean as of this coming Wednesday. After a couple of weeks of sanding and using Fiberglass paint remover on the built up antifoul on Katy Too, I will have the remainder soda blasted (using baking soda). The bottom is also dry as I've had it checked for moisture. Because I discovered blisters last fall I have decided to barrier coat the hull, and would appreciate some advice from those of you who have done this job before.
I know of three barrier coat products -- Interlux VC Tar, Interprotect 2001E, also from Interlux, and Pettit Protect, from Pettit. I have only a limited amount of time to do this since the boat is scheduled for launch on May 16.
Does anyone out there have a recommendation for any of these products, or for any that I don't know about? I plan to select one based on: a) the amount of time it takes to finish the job, b) the difficulty of the job, c) the number of coats needed to make an effective barrier coat (the fewer the better), d) the overall cost of the process.
If you know of other considerations that haven't penetrated my brain please let me know. Also, if you have used any barrier coat product and have recommendations (good or bad) please let me know.
Thanks for any help you can give me, and may this sailing season be a great one for you, your crew, and your boat.
Fair winds,
Peter Kozup, S/V Katy Too
Cape Dory 26, Hull #42

[John Ring]

Peter,

It's the prep work that takes all the time. Once the hull is stripped down, the rest is fairly easy. Of course, I'm assuming you've already ground out, dried, and filled the old blisters with thickened epoxy, stripped the hull down to gel coat, and you're now ready to put a barrier coat on the entire hull. Before you start rolling on epoxy, wipe the hull down with a good stripper, like Pettit #95, to remove any grease or left over mold release. Now you can roll away, and getting three coats on in one day is pretty easy if you time it right. Once the barrier coat is on, it needs to fully cure for a few days. Then, you must give it a good wash to remove amine, and go over it lightly with a palm sander to give it some tooth for the bottom paint to hold on to. Palm sanding shouldn't take more than a few hours or so for a CD26. Then you are ready to roll on your bottom paint and go sailing.

If you're ready to roll on the barrier coat, consider Pettit. I used Pettit, and found it very easy to work with. You can take a look at how I did my CD28 here: http://www.yachttantalus.com/Barrier%20Coat.htm

Good Luck,
John Ring
CD28 #241 Tantalus
www.yachttantalus.com

[Dan & Pat]

Interprotect 2001E is what I've been working with. Make sure you read the distructions (directions/instructions) on both, your bottom paint as well as the barrier coating.

I'm using the barrier coat and topping off with Supershipbottom Dark Blue paint, which is a hard surface - shiny ablative paint.
www.supershipbottom.com

The directions on the paint say that if you use barrier coating, allow the barrier coat to cure no more than 6 hours, otherwise you have to sand the surface before applying the bottom paint. You can save yourself a lot of extra work if you apply it the same day.

[Ron M.]

DanPat,
Thats what I wanted to hear - apply bottom paint to new barrier coat WITHOUT sanding. What brand of paint recommends this ?
________
Buy vaporizers

[Dan & Pat]

Supershipbottom Paint... IMHO It is the best product of its kind available on the market.

Its not the cheapest, but produces great results. Besides being durable for several seasons in and out of the water, you don't have to apply it just before launching the boat. It is a hard bodied paint - meaning you get a slippery finish rather than a chaulky finish.

Go to www.supershipbottom.com

[winthrop fisher]

hey, try this 2001E is the best then prime and paint....winthrop

[bottomscraper]

DanPat,
Thats what I wanted to hear - apply bottom paint to new barrier coat WITHOUT sanding. What brand of paint recommends this ?

I used West Marine brand epoxy barrier coat a few years ago on our previous boat. I'm not sure if they make it anymore but you did not need to sand between coats or before the bottom paint but there was a narrow time window, I think the bottom paint needed to be applied within 7 hours after the last coat of epoxy. I remember waiting for a weather window that would allow all of the coats of epoxy and bottom paint. I think the Interprotect 2000E can also be used this way. Check out instructions here: http://www.yachtpaint.com/Images/15_6819.pdf

[marv brinn]

we have cut thru the gel coat in several areas due to our sanding. I am assuming we will have to fill these areas in before we put our barrier coats on right??

[marilou]

Stop sanding.
Take a look at the hull.
Loose bottom paint - scrape.
Gel coat blisters need to be identified when the boat is hauled, not 30 days later. Mark any "pimples" whith a marker pin.
If you have sanded the gel coat off, then I would apply Epoxy(West) to these areas. Epoxy is a good choice as barrier coat, but needs to be sanded/primed before applying bottom paint/vs. barrier coat products...

[aja]

Peter,

We stripped down our cd25 a number of years ago with very good results. It stills looks very good today with only 1 coat/type of bottom paint instead of 20 layers.

Here is my opinion about epoxy barrier coats. An opinion that a lot of fellow members may not agree with.
Don't bother. (unless your hull is in pathetically bad shape) Your barrier coat can not only seal the water out, but just as well seal it in. My company has been manufacturing with 2 part epoxies for 10 years and we have slowly moved away from the compound. There are much better things on the horizon.
Remove all your bottom paint. Fix your gelcoat blisters and gelcoat breeches from sanding, paint the bottom with a good quality bottom paint and lets go sailing

don

[Zeida]

bANDOLERA II, my CD-33 just spent 10 days out of the water for her bottom maintenance, three years after the last haul-out. After lots of research (Internet,etc) about how to deal with the blisters and the osmosis that has plagued my boat, this is what I did: sanded down the hull to the gelcoat. That way we clearly saw the old REPAIRED blisters, still nice and dry and in place. We had used WaterTight Interprotect the last times. No new "weeping" was observed during the first week of the boat out of the water. Seven "quarter size" blisters in the rudder were ground out and let them weep until they were relatively dry. Washed the hull daily with water and acetone. The very few blisters observed this time were also drilled out, cleaned and filled with WaterTight Interprotect from Interlux. On day 8, we applied one coat of Primocon, an underwater primer by Interlux, to the entire hull. This is NOT a barrier coat, just an underwater primer. It was put on in the morning. By noon, it was dry. At 1 pm we started applying the Trinidad SR Pro Antifouling bottom paint, directly over the Primocon, no sanding required. Applied three coats (3 gallons) of the bottom paint and had the boat splashed next morning. Unless the hull is in very good shape, no blisters and dry, it is USELESS to apply any barrier coat. You are just sealing the moisture in, making the blister problem WORSE. I had a marine surveyor come and check out the integrity of the hull, and my blisters (well over two thousand, dime size) are mostly cosmetic, and pose no damage to the glass matt. He also recommended NOT to barrier coat the hull. Just grind out the blisters, clean them, fill them, and on with the bottom paint. That is what we did.

The OTHER alternative is to peel off the entire gel coat, keep the boat out of the water until the hull is absolutely dry, THEN by all means, apply an Epoxy Barrier coat, as many coats as indicated, usually three of four to the required thickness, and over that, your bottom paint and that will be the end of all blisters. As soon as I win the Florida Lottery I will do that. In the meantime, Bandolera is back in the water and I'll be sailing this weekend. Cheers.

[Matt Cawthorne]

When I bought my boat 13 years ago there were a pile of small blisters. I decided to barrier coat up to the water-line with West epoxy. Little did I know that the water line on this boat was below the surface. A couple of years later I got some blisters above where I had barrier coated originally. I stripped the boot stripe, barrier coated up an extra 4 inches and raised the water line 2 inches. 12 years later I got the first blister through the barrier coat. It turns out that the blister was between two layers of gelcoat. They must have had too much catalyst in the gelcoat or waited far too long between coats because I can scrape 1 layer of gelcoat off and leave the other. Above the waterline the gelcoat is an Ultraviolet sun shield and makes a pretty structure. Consider what gelcoat does for you below the waterline.......Nothing. It is a moisture highway to the hull. If you have sanded through the gelcoat and the boat is still fair, then add an extra layer of epoxy and sleep well. If I had it to do over again, I would strip the gelcoat off before applying the barrier coat. My problem may well be unique and local to a few spots. Time will tell. I have not heard of anyone else having the gelcoat exfoliate.

Matt

[Steve Laume]

When I stripped all the bottom paint off of my Typhoon, I just did not have the time or energy to barrier coat the bottom. Some of the people walking around the yard indicated that it would be a good idea as I had gone that far. I just went with fresh bottom paint for a couple of years we were using the boat with no problems. When I did the CD-30, which was a much bigger job, I got the same advice in a different yard. Wanting to do a really good job I went ahead and barrier coated the bottom before painting. I figured it would at least replace the amount of gel coat I sanded off. Well a little over a year later I hauled mid season and found a bunch of tiny little blisters under the barrier coat. There never were or have been any blisters under the gel coat. So the barrier coat was a big mistake. It just amounted to wasted time and money. Not to mention the time it takes to break through and dry out the tiny little blisters. If it isn't broke... Steve. in .

[George Shaunfield]

I will not comment on whether or not you should barrier coat your hull. With my "new" boat (Westsail 28) I did not have a choice since the gel coat was stripped off about 6 years ago. After doing some research I decided to go with Interlux Interprotect 2000 instead of West System because of better information on what needed to be done.

My boat had hundreds of 1/2" blisters and a few larger spots that appeared to be a result of layup deficiencies. I ground out virtually all of them, filed them with Interlux Epiglass with filler powder, sanded those places and refilled/faired. Then I sanded the entire hull to get rid of all of the oxidation. Next came two coats of Interlux Epiglass (epoxy). The second coat can be applied when the first coat is tacky. After the second coat has dried overnight it was necessary to wash with soapy water and a stiff brush. Then I sanded the epoxy as recommended. Then I applied the first coat of Interprotect 2000. Subsequent coats can be applied after it is tacky or anytime within two weeks without having to sand (this flexibility was great for me!). Also, I used grey, then white, then grey, then white. Alternating the colors made it easy to see that I got full coverage with each coat. (Not as easy with the two coats of clear epoxy.) And I was able to apply the first coat of antifouling paint when the last coat of Interprotect 2000 was tacky (without having to sand!) if done in the specified time frame based on temperature. I used Pettit Trinadad antifouling because I know from experience that it works well in Gulf Coast waters and lasts a long time. It will take a few years before I can report on the outcome of this project.

Here is a 12-page booklet that answers a lot of questions about barrier coating with Interprotect 2000 http://www.yachtpaint.com/USA/hotlinks/ ... lletin.pdf. At this web site there is also a lengthy Epiglass Manual on their epoxy.

I hope this is helpful.
George