What osmosis barrier to use if any when applying coppercoat?

[CatNewBee]

Hello,

I have a 4 years old Lagoon Catamaran with traditional anti-fouling and I want to switch to coppercoat. Main reason is, we want to cruise an extended time and will not haul out the boat frequently, I intent to scrub the bottom while in the water from time to time and a hard antifouling is a good idea for that.

As far as I read, the hull must be cleaned down to the gelcoat, sanded, de-greased and de-waxed, washed and dried. What products shall be used for this to not negatively affect the bond of the next layer.

After this, coppercoat must be painted quickliy at at least 4 layers. Also saw some notions that they use on different materials some primer to increase the strength of the bond.

I wonder If it would be a good idea to paint some epoxy primer anti-osmosis barrier first on the gelcoat to improve the bonding and to add more protection to the hull before painting the coppercoat. The hull will be prepared any way with a lot of effort, I think it is not too much more effort to paint some more coats, but could extend the lifetime of the hull. But if the primer-coppercoat or primer-gelcoat do not stick to each other that could ruin the whole work.

What products are the best to use to increase the bond and how many layers of osmosis protection primer is advisable? How should they be applied (wet in wet or wait to cure first and then sanding + coppercoat on top?)

Is it advisable too strip the old paint by chemical products like anti-fouling stripper or can they reduce the adhesion of the primer / coppercoat later, what is the best way to get rid of the old bottom paint? I read, acetone must be avoided too. I guess a mechanical removal would be the safest way...

A lot of questions, I know.

Thank you very much!

[44'cruisingcat]

A friend is coppercoating his boat at present. We discussed various epoxy barrier coats, he seems to have decided on using straight epoxy.

[rom]

There is already a lot of information about that on the forum but since I did it last month on my L440 I'll share my experience...

It took me 2 weeks of hard work. I used the sandvik scraper, small one and big one with the handle. 2 blades for each. A 150mm orbital sander. I have the blue bosch, it is heavy. A compressed air would be much easier but not the same price... If you scrap well then only a few 80 grit disc will be enough.

There is quite a fair amount of gelcoat on Lagoons so you are very unlikely to go through.

I took this opportunity to relocate some though hulls, and to epoxy repair some deep scratches on rudders and keels. Also a good opportunity to realign the rudders and to grease (or change) their bearings if needed.

Then I used oxalic acid to clean the deck and sides, then washed the whole boat with soap and water, then final cleaning below WL with acetone right before painting. I am not aware of any trouble with acetone on fiberglass and gelcoat.

I used seajet 117 expoy primer, 2 layers. Then seajet 033 shogun, 2 layers. If I had to do it again I would only use 1 layer of epoxy primer, that's what lagoon does on new boats, and lagoons are not subject to osmosis anyway. It was real hard to get an homogeneous result with the second epoxy layer.

I like the idea of a durable hard antifoul that you would clean underwater with a sponge from time to time, but after going through that process I want something that is easy to remove ...

good luck !

[rom]

Originally Posted by 44'cruisingcat

A friend is coppercoating his boat at present. We discussed various epoxy barrier coats, he seems to have decided on using straight epoxy.

Straight epoxy is certainly a good barrier, but I do not believe it is a good primer. AFAIK even epoxy boats use an epoxy primer before AF.

[CatNewBee]

Coppercoat explicitly warns to not use Aceton on the gelcoat, because it reduces adhesion of the coppercoat and can lead to peeling off.

It seems it resolves the wax / oil and it even gets deeper in the gelcoat and worsens the connection of the layers.

I saw this warning several times on their instruction videos. This is also the reason why I am unsure what material to use to de-grease de-wax the hull.

[HopCar]

Many years ago I put a copper loaded epoxy on my boat. I figured it would at least work to prevent blisters even if it wasn't a good anti foulant.

It wasn't a good antifoulant, I painted the bottom a year later. A few years after that I had the gel coat ground off and replaced with interlux 2000. The blisters were very bad.

[Yes maybe]

My research on this subject lead me here: ABS Technologies Marine enquires@marine.abs-technologies.com.au

There prep sheet also informs not to use oil based or acetone as cleaning agents.

regs. Boris.

[CatNewBee]

yes, aceton seems to be a problem...

[CarlF]

I understand some see Coppercoat as a "better paint system" but I'm not sure it's cost justified just to reduce hauling.

This is going to be really expensive - not to mention the added risk of doing something that's unusual enough that you have to ask questions on the internet about it.

I can't think of a time when I haven't had to haul my boat in more than two years - usually just to take a close look at the underside. But sometimes because I hit something

And if you are willing to scrub increasingly often, you can go a really long time on old bottom paint until it's convenient to haul. If the boat's not painted with ablative, why not just put on a top hard paint like Petit Trinidad and haul a couple of times?

[CatNewBee]

Copper is a great protection and it is very effective. Even on Land on roofs it prevent growth of moss etc. Copper based biocides has been used for ages.

It's not a better paint system, it is THE professional durable anti-fouling, that is used on commercial vessels for a long time and they are not hauled out every 6 months for scrubbing.

It is expensive, but regular anti-fouling ist expensive too. A haul out and pressure-washing costs in the Med in France 1.650€, for a one layer antifouling paint done by the marina you pay for a 40ft catamaran is about 8.750€, if you do it yourself you pay for 14 days on the dry with all facilities (Water, Powersupply and cleanup by the marina) about 2.000€, storage on the dry and not using the "facilities", cleanup yourself, no air gun spraying, only 6A power etc.. you pay 600€. The paint adds up to 600€ for the cat for one coat (approx. 5l paint, I guess 80m² surface to be painted), so the cheapest version will cost you a lot of elbow grease and 1.200€ for paint, marina + 1.650 for the haul out every year.

You need 20l of coppercoat, it will cost 2.200€ incl taxes and delivery. Once done properly you do not need to haul out again, you can scrub underwater. And even if you haul out for inspection, you do not need to stay on the dry, you can immediately water the vessel again after the pressure-washing, so you save 1.200 per year for not staying on the dry and not painting with new paint.
If you not haul out at all, you save 3.000€/year DIY or 10.000€/year when painting done by the marina. (prices for a 40ft. Lagoon in France, if you go to Algeria, you might have to pay the half price)

But its not just the costs. The hard cover is much easier to clean, you can use tides to fall dry and clean the bottom quickly if needed, no re-paint necessary for the next decade. Also the anti-osmosis barrier under the copper coat is worth a consideration.

Of course it has to be done properly and it has to be activated by light sanding after the curing time.

And even if you decide one day to use traditional abrasive antifouling, you can paint it on top of the coppercoat easily, it is epoxy based, no need to strip it down, its hard enough as an underground for paint similar to gelcoat, and if in doubt, use a primer.

It's not the costs for the paint, it's the marina fees and the work, that adds up. You save money already in the second season.

[Martkimwat]

Contact Coppercoat themselves for best advise, they are very helpful. I have coppercoated two of my boats myself, having had coppercoat on two previous boats. I had the hulls soft grit blasted first then used a single coat of epoxy base layer then when dry applied the coppercoat. The coppercoat needs to be applied when the previous coat has gone non tacky but you can still mark it easily with your finger nail which effectively means that the second coat goes on as soon as you have applied the first coat, as the first coat drys very quicly to a non tacky condition. The last coat may need a couple of hours before applying. You must do it in one day as otherwise you will need to allow the previous coats to dry hard (couple of days) abrade and then apply, which is not at all optimal. Temperature needs to be at least 15ºC and a good breeze helps drying as well. If you have props supporting the hull, you will need to allow about a week for the surface to dry sufficiently before moving the supports to the coppercoated area if you don't want paint 'creep' and so that you can then do the patches left by the supports. Although they say you should keep going till all the coppercoat provided is used up, remember to keep a little back to do the support patches. It is guaranteed for 7 years but they have examples of boats still going with their original coppercoated bottoms after 27 years. It's cost, based over 7 years is the same as a decent antifoul and you are not going to need to remove it every few years before re antifouling. Just remeber to abrade the surface with a scotchbrite pad before the first immersion to expose the first layer of copper.
I used the small 4" and 6" rollers and split the coppercoat down into smaller batches, typically a quarter of the copper and epoxy, this then took 15~20 minutes to apply and allowed me to do so before it got tacky and started pulling off with the roller. I also found it helped to keep the two bottles of epoxy and hardener in a warm bucket of water as it made it flow much easier. Note that the epoxy is water soluble when wet so easy to clean up. The boats I did myself were a Tradewind 33 which took 10 batches of coppercoat and a Parker 27 which took 6 batches. Both were easy to do in one day, starting at 8am and finished by 4~5pm. The yard where I keep my boats in the winter do coppercoating and they do it indoors with two guys working one side each and they do it quicker still, but then they also use radiant heaters to help with the drying.
Coppercoats are based in UK and their contact details are easily available online

[Suijin]

When it comes to stripping the old paint off, I would gather the tools for several different methods. The right (as in most effective, least laborious method) is going to be a function of the condition of the old paint, what type it is, and what's underneath.

I would start by going at it with a good quality professional grade carbide scraper. It may strip the paint off relatively easily and leave the surface relatively smooth and ready for a light sanding for tooth and overall smoothness.

You can go at it with an orbital and the most aggressive grit you can find (probably 40) but be prepared for it to just burnish the paint and take forever. YMMV depending on what type and how much paint there is on the boat.

Chemical stripping, while attractive in theory, can end up being a nightmare. Coat after coat, even when covered to help vapors eat into the paint, seem to do nothing at all on some paints. But it might be worth a try if you prefer.

If you have the chops for it, 36 grit on a variable speed grinder/polisher and a soft pad is probably the fastest method but you have to be expert to not end up putting moguls in your hull.

If you're going to take everything off I would certainly suggest a good barrier coat if only because it gives you a good foundation layer that you know is there and can identify going forward. You've one all the hard work of taking the old paint off, protect your investment in labor and do it right. I would go with at least four coats of any product. If you want the best surface result possible I would put at least four coats on, sand out the orange peel, then put another final coat on, then whatever your antifoul. And I would use a purpose designed barrier coat, not straight epoxy. Interlux for example is designed to stay hot coatable for something like a month which is hugely helpful in managing your work schedule.

The issue you need to be concerned with is compatibility. It's generally a good idea to use a barrier coat that is from the same manufacturer of the antifouling paint you're using as folks have had troubles when "mixing and matching". Going with the same manufacturer eliminates that guesswork. In your case I would call Coppercoat directly and ask them what barrier coat to use. If they maintain even when pressed that you should use none, I would probably eliminate them from consideration and go with a different system.

Acetone is not a great choice for surface prep for coatings in general. It seems to act as a surficant and cause fish-eyeing. Denatured alcohol is probably the best choice.

[boatman61]

My experiences with epoxy are West Systems.. I used warm soapy water to wash off the waxing that formed between coats then a light sanding before applying the next.
Only used Acetone for cleaning my gear.. and bits of me..

[David B]

Originally Posted by CatNewBee

Hello,

I have a 4 years old Lagoon Catamaran with traditional anti-fouling and I want to switch to coppercoat. Main reason is, we want to cruise an extended time and will not haul out the boat frequently, I intent to scrub the bottom while in the water from time to time and a hard antifouling is a good idea for that.

As far as I read, the hull must be cleaned down to the gelcoat, sanded, de-greased and de-waxed, washed and dried. What products shall be used for this to not negatively affect the bond of the next layer.

After this, coppercoat must be painted quickliy at at least 4 layers. Also saw some notions that they use on different materials some primer to increase the strength of the bond.

I wonder If it would be a good idea to paint some epoxy primer anti-osmosis barrier first on the gelcoat to improve the bonding and to add more protection to the hull before painting the coppercoat. The hull will be prepared any way with a lot of effort, I think it is not too much more effort to paint some more coats, but could extend the lifetime of the hull. But if the primer-coppercoat or primer-gelcoat do not stick to each other that could ruin the whole work.

What products are the best to use to increase the bond and how many layers of osmosis protection primer is advisable? How should they be applied (wet in wet or wait to cure first and then sanding + coppercoat on top?)

Is it advisable too strip the old paint by chemical products like anti-fouling stripper or can they reduce the adhesion of the primer / coppercoat later, what is the best way to get rid of the old bottom paint? I read, acetone must be avoided too. I guess a mechanical removal would be the safest way...

A lot of questions, I know.

Thank you very much!

We went through this in 2012. New boat, and supposedly OK with the modern resins and better controlled mixing. However the thought was that Coppercoat is going to be on the hull for the next 10-20 years or more, so even though apparently most Coppercoat is applied straight onto abraded gelcoat (it is two-pack epoxy after all, and adhesion is excellent), I figured that a bit extra spent at the beginning was a good 'belt & braces' investment.

We went for the epoxy barrier coat supplied by the Coppercoat dealer in France. Being solvent free, the Coppercoat can then go on while still soft. But if you cannot get solvent free epoxy barrier coat, then with Coppercoat being water-based, you need to allow time for the solvent to fully evaporate out or you may end up with solvent entrapment issues (read adhesion).
For the same reasons, do not use any thinners, or acetone. Isopropyl alcohol is the thinner used for Coppercoat (if required at all), so you could wipe over with that.
Our experience after six seasons in the Med, is that the Coppercoat is as good as the first year, and we expect it to last at least another 10 years, but quite probably a lot longer going by others experiences. If we haul at the end of a season, the hull just gets a pressure wash. If we don't haul, we either give it a scrub, or send a diver down. Nothing hard has ever been found on the hull, just a bit of the usual slime, and one year, a patch of 'scribbly worm' that just wiped off with my bare hand.

While I think we were over-charged for the Coppercoat application (the 'credit' we received in lieu of the regular antifouling paint and application of same was minimal, and the extra labour charge for Coppercoat application was pretty steep), going with Coppercoat has saved us a heap of inconvenience and cost.

For your existing antifouling, go for a solvent-free stripper if you do not want to scrape or sand the old stuff off. Another reason to do so, is solvent-based strippers can as you suggest, get into the gelcoat - it would worry me!

Assuming you don't want to go for the easy but expensive process of soda or grit blasting, I would strip, scrape, pressure wash, abrade, wipe over, then the next day, start applying the barrier coat (2-3 coats wet-on-tacky).
Then assuming you are using solvent-based barrier coat, let it cure hard, give a good sand to key the surface, wait another few days to let all solvent evaporate out, then wipe over with isopropyl alcohol, and apply at least four coats of Coppercoat wet-on-tacky. I would order enough for a fifth coat around the waterline. I wish someone had told us that! From our experience, the waterline area after a few years has a light 'texture', indicating some erosion (wave action and oxygen). An extra coat or two there, would have evened out the wear over the entire hull.

I hope that helps.

[44'cruisingcat]

Originally Posted by rom

Straight epoxy is certainly a good barrier, but I do not believe it is a good primer. AFAIK even epoxy boats use an epoxy primer before AF.

The intention is to use slow hardener and start applying the coppercoat before the epoxy is fully cured.