Complete a/f removal: WHEN?

[MapisM]

Elessar, can you elaborate on your point regarding removing the gelcoat if you want to replace foul release coating please? I use aquamarine and have not read or been told any such thing. But happy to be proven wrong.

I'd be interested to hear about your experience with Aquamarine, because I half abandoned the alternative of foul release products after reading that they are only effective as long as the boat doesn't stay moored for long - like no more that 2 or 3 weeks in a row.
Which is the reason why it's mostly used in commercial vessels, I reckon.
For my typical usage, the boat rarely stays more than 2 or 3 DAYS without moving, but in winter she could well sit in her berth for 2 MONTHS, if not more...
Wadduthink?

 

[Elessar]

Apparently soda blasting is a less aggresive alternative to sand blasting.

see post 17 and note "gel coat is very soft and anything that can remove the antifoul can damage the gelcoat in clumsy hands."

 

[Deleted User YDKXO]

Btw, before anyone suggests that, nope, enjoying her also during the winter is not much of an attraction for us, because we already know the area pretty well, and winter weather in the N Adriatic can be worse than in the CdA - let alone the much more southern latitudes we are by now used to

Its not a well known fact but actually average winter temps in Venice are lower than London and I certainly experienced some freezing cold days whilst overwintering in Monfalcone. Brrr!

With regard to the antifoul layers, Andrea at Sacirn told me that the time to remove all the old antifouling layers was when you could observe the old layers starting to flake off in places. In other words the old layers may not be a solid base for any further layers. He stripped my boat in 2015/16 when it was 8/9 years old

Sorry can't tell you what process he used but may be worth sending him an email for advice

 

[Elessar]

Elessar, can you elaborate on your point regarding removing the gelcoat if you want to replace foul release coating please? I use aquamarine and have not read or been told any such thing. But happy to be proven wrong.

Thanks

They are AFAIK silicone based and as such very difficult to remove in a way that you can paint over. I know of one boat that had to be peeled to overcoat. Sanding doesn't work as all the silicone ends up in the bottom of the sanded crevices. It is impossible to blast off. Blasting requires a degree of hardness, the removal energy comes from the splitting of the blast media when it hit the hard surface - which is why you can etch glass with patterns using foam templates. Glass is much harder than foam, so all the energy is expended on the glass. With spongy silicone on gelcoat, you will have the same effect.

One boat isn't much evidence, but as I say I wouldn't want to be an early adopter.

I tried some of these products as test patches over my coppercoat on may last boat. I wasn't impressed.

However I helped a well known forumite put some on his props and I will be using some on mine as that does look encouraging.

 

[Elessar]

Thanks everybody, some useful food for thought.
One specific question on this...

Does coppercoat it "TOO" mean on top of 6 epoxy coats?!?

I asked some specialists around here in the meantime, and they confirmed me that with CC it's possible to use directly two coats of its own primer (a non-solvent epoxy resin, as I understood), and 4 coats of CC (also non-solvent epoxy based) on top.

Otoh, if going for traditional a/f, yes, I was also recommended a full epoxy cycle.
Actually with 5 rather than 6 coats, which allegedly is the supplier (International) recommendation.
They didn't mention to me the different colors though, which sounds like a clever idea.
Is there any specific product available in different colors which you used for that purpose?

Ref. old a/f removal, the most popular method around here seem to be dry blasting, with either walnut shell or garnet (an Australian mineral, as I understand).
I was told that slurry blasting is usually done with bicarbonate instead, but the cost is much higher, and allegedly not worth paying, provided that the operator works well with dry blasting.
Which is a given, sort of, considering that the company I got in touch with is widely used in this area, and they make literally hundreds of boats every season.

No I wouldn't normally put coppercoat on top of 6 coats. In fact I'd normally avoid solvented epoxy under coppercoat.

If the hull is all good coppercoat only. If you need epoxy because the gelcoat is thin then 2 coats of solvent free the consecutive 2 days before copeprcoat is the way to go. So your guys are right - it's not coppercoat primer as such just solvent free epoxy.
They're not technically right about coppercoat being solvent free, but the solvent in coppercoat is water. It is VoC free. That's a bit pedantic.......

But if you miss a day you have to sand the lot or it won't stick.

If going solvented, international do it in grey and green to do alternate colours. 5 or 6 coats - not much difference either will be fine, but I'd do 6 you're going to have the paint for it in one colour or another.

We used to slurry blast with recycled glass. Olivine works well too in wet blasts, but no benefit over glass and more expensive.

 

[Elessar]

Sorry can't tell you what process he used but may be worth sending him an email for advice

looks like scraped and sanded to me. Very hard work.

 

[wellf100]

They are AFAIK silicone based and as such very difficult to remove in a way that you can paint over. I know of one boat that had to be peeled to overcoat. Sanding doesn't work as all the silicone ends up in the bottom of the sanded crevices. It is impossible to blast off. Blasting requires a degree of hardness, the removal energy comes from the splitting of the blast media when it hit the hard surface - which is why you can etch glass with patterns using foam templates. Glass is much harder than foam, so all the energy is expended on the glass. With spongy silicone on gelcoat, you will have the same effect.

One boat isn't much evidence, but as I say I wouldn't want to be an early adopter.

I tried some of these products as test patches over my coppercoat on may last boat. I wasn't impressed.

However I helped a well known forumite put some on his props and I will be using some on mine as that does look encouraging.

It's a silicone top layer on top of a base primer coat of paint. So not sure why it would be any different to a/f on top of a primer coat.
I notice that Aquamarine now advise applying an epoxy base layer before the foul release base coat and silicone top coat.

 

[wellf100]

I'd be interested to hear about your experience with Aquamarine, because I half abandoned the alternative of foul release products after reading that they are only effective as long as the boat doesn't stay moored for long - like no more that 2 or 3 weeks in a row.
Which is the reason why it's mostly used in commercial vessels, I reckon.
For my typical usage, the boat rarely stays more than 2 or 3 DAYS without moving, but in winter she could well sit in her berth for 2 MONTHS, if not more...
Wadduthink?

Hi Mapis, my boat stays stationary for months on end over the winter and sometimes several weeks at a time in the summer when I'm away. You get plenty of growth but the point is you can wipe it away easily. I'm coming to the end of 3 years and it's working as well as it did at the start. But the main thing I would point out is that driving the boat alone is not really enough to keep it clean as some growth won't fall off by water friction alone. You would need to wipe the hull regularly to keep it completely clean.

I use Aquamarine but Hempel also have one called Silic One which came out top in the MBY test a few years ago (primer coat and silicon top coat) which sounded like it really did release fouling with just minimal water movement, however the top coat has to be reapplied every year which was as opposed to one of the main USP's of Aquamarine and Copper Coat being multi year.

To be honest I think you would need to get some feedback from med based users of Aquamarine to get the best info. There's a few references on their website but maybe local agents could point to some users local to you if your interested.

I've pondered many times as to whether i would go for Copper Coat or this if had to decide again and on a much bigger boat than i currently have. I think my tendency would be towards copper coat just because of the low maintenance of it but i would want to get some real feedback of Aquamarine on bigger boats where keeping it clean might be more of a hassle before deciding. I know there are some boats that have had Aquamarine applied in the last year in Jersey before heading down to the med.

 

[Elessar]

It's a silicone top layer on top of a base primer coat of paint. So not sure why it would be any different to a/f on top of a primer coat.
I notice that Aquamarine now advise applying an epoxy base layer before the foul release base coat and silicone top coat.

Well I don't see how you can get the silicone off the paint, but you might be right. I'd rather learn from your experience than the other way around, so it isn't for me.

 

[wellf100]

Well I don't see how you can get the silicone off the paint, but you might be right. I'd rather learn from your experience than the other way around, so it isn't for me.

I think part of your original point is that you have to remove it all to put something else on which is certainly true. You can't just remove the silicon and apply traditional a/f on top of the existing base. However in reference to your comment about sanding off, the silicon is on a base coat and not directly on the gel coat . Both base and silicone can be scrapped, blasted or sanded off in the normal way as far as I'm aware.

 

[Elessar]

I think part of your original point is that you have to remove it all to put something else on which is certainly true. You can't just remove the silicon and apply traditional a/f on top of the existing base. However in reference to your comment about sanding off, the silicon is on a base coat and not directly on the gel coat . Both base and silicone can be scrapped, blasted or sanded off in the normal way as far as I'm aware.

I still don't see how you can scrape or sand paint with silicone on without contaminating the gelcoat beneath with silicone, nor can I see how to blast spongy silicone. Happy to watch others try.

 

[wellf100]

I still don't see how you can scrape or sand paint with silicone on without contaminating the gelcoat beneath with silicone, nor can I see how to blast spongy silicone. Happy to watch others try.

OK, I've no idea whether this is a problem. I'll ask them about it sometime. What problem does it cause? Do you mean that new epoxy/primer/antifoul wouldn't adhere properly?

 

[Ian h]

when I had my antifoul removal business, the average was about 7 years.

If the antifoul is all off and your moisture levels are OK, it's daft not to epoxy it. Gelcoat is not waterproof, epoxy is as good as waterproof. For DIY 6 coats of solvented epoxy in alternate colours is good for all sorts of reasons, including easy removal of antifoul in the future (you can breach just the top epoxy coat with your abrasive and the colours let you know where you are)

Personally I'd coppercoat it too and never have to remove antifoul again. Though thats another can of worms if you used solvented epoxy.

I'm not convinced on fouling release systems for hulls and I have trialled some. And if they don't work you need to remove and replace the gelcoat to use paint aver again, so I wouldn't be an early adopter. I think they work on props though now.

As for slurry v soda v dry blasting. The softer and slower the process, the less experienced/skilled the operator can be and still get a decent result. But it is all about the operator, gel coat is very soft and anything that can remove the antifoul can damage the gelcoat in clumsy hands. See the results that the actual operator has achieved. Good ones will leave some antifoul for sanding off, not try and achieve pure white.

My boat is dry stacked since I purchased in 2009, The old Antifoul is looking bit of a mess now, What would your thoughts be on what I should do ? It will still be dry stacked

 

[Elessar]

OK, I've no idea whether this is a problem. I'll ask them about it sometime. What problem does it cause? Do you mean that new epoxy/primer/antifoul wouldn't adhere properly?

I don't think anything will adhere to anything contaminated with silicone. But as I said I might be wrong.

 

[Elessar]

My boat is dry stacked since I purchased in 2009, The old Antifoul is looking bit of a mess now, What would your thoughts be on what I should do ? It will still be dry stacked

Strip and epoxy. Or strip and coppercoat. Both will last the lifetime of the boat. Very unlikely you can get back to bare GRP unless the original antifoul people were very lazy with their sanding/prep.

 

[MapisM]

I've pondered many times as to whether i would go for Copper Coat or this if had to decide again and on a much bigger boat than i currently have. I think my tendency would be towards copper coat just because of the low maintenance of it but i would want to get some real feedback of Aquamarine on bigger boats where keeping it clean might be more of a hassle before deciding. I know there are some boats that have had Aquamarine applied in the last year in Jersey before heading down to the med.

Yep, I'm also making up my mind towards CC rather than Aquamarine or similar, for the reasons discussed.

But if you would get any additional feedbacks on how easily fouling can be cleaned away from a hull coated with a foul release system after the boat has not moved for longish periods, I for one would be interested! :encouragement:

 

[MapisM]

Strip and epoxy. Or strip and coppercoat. Both will last the lifetime of the boat. Very unlikely you can get back to bare GRP unless the original antifoul people were very lazy with their sanding/prep.

I'm confused.
Do you mean it's unlikely that you can get back to bare GELCOAT (without damaging in, I guess you mean in this case), or bare GRP?
I would think it's relatively easy to strip everything up to bare GRP, though it would only make sense for hulls badly affected by osmosis, I reckon...

 

[Elessar]

I'm confused.
Do you mean it's unlikely that you can get back to bare GELCOAT (without damaging in, I guess you mean in this case), or bare GRP?
I would think it's relatively easy to strip everything up to bare GRP, though it would only make sense for hulls badly affected by osmosis, I reckon...

You are quite correct. I meant bare gelcoat.

 

[wellf100]

Yep, I'm also making up my mind towards CC rather than Aquamarine or similar, for the reasons discussed.

But if you would get any additional feedbacks on how easily fouling can be cleaned away from a hull coated with a foul release system after the boat has not moved for longish periods, I for one would be interested! :encouragement:

sure, i'll see if i can record something however i imagine the types of fouling are different in the med to here. In the meantime here's the ones on their website:
https://www.aquamarineuk.com/pages/take-a-look-at-the-video-gallery

here's the MBY test which had traditional antifoul, Aquamarine and Hempel Silic One test in UK and Med:
http://www.mby.com/maintenance/tried-tested-antifoul-81351


cheers,
Rich

 

[BartW]

We had her sand blasted 4y ago when she was 23yo, right before we mounted the fin stabs,
Around the stabs, we have added extra layers of grp, so in that zone she had to be sanded to bare grp anyway.

Blue Angel had many layers of old hard antifouling, at least 6 layers with different colors,
Apart from the esthetics, and the smoothness of the hull, another argument was the weight of the paint,
In a rough calculation about 500kg of old paint went off.

After sand blasting, The yard has put a epoxy coating (by hand) , and Micron77 antifouling

And since then, each year, we had her pressure washed, antifouling nearly completely off, coating stay’s intact
and place just one new layer of Micron 77

Now I have one concern,
When we purchased the boat in 2011 she had zero osmosis (confirmed by the surveyer)
One season after the sand blasting we discovered (actually the painter did) a few spots of osmosis in the zone between the props.
I believe they did only “one” layer of epoxy hull coating,
Could the sand blasting / not enough layers of epoxy, be a reason for these spots of osmosis or is it just age of the boat ?

Unfortunately I have no better contribution/ answer to your thread / question