Taking off old antifouling or not

[BartW]

When we had the survey on Blue Angel april 2011, the surveyor GC, discovered there were 5 or 6 layers of old antifoul, he advised that we could do another layer on top,
Now we are 2 seasons later (2 times antifouling since then)
I am very happy with the antifouling.
Despite the fact that the surface is not completely smooth, we have almost no growth on it, not last year neither this year.
I don’t notice much difference in speed now compared to just after the new antifouling,

I’m planning my maintenance for next season, and have a good quotation for new antifouling (2100euro + lift out)
from a small yard in Sanary sur mèr, specialized in old wooden boat (had some good comments from a neighbor in Toulon)
http://www.chantiernavaldesbaux.fr/

Now I asked this yard their advice about taking off old layers of antifouling, and they gave me a quotation for “Hydrogommage”
Which is in simple words: Cutting off the old layers with pressurized water + abrasive material
and then repairing eventual punctures, 2 layers of special primer, and 2 layers of antifouling,
But the bill is more steep: 16500 + lift out, for the whole process.

I’m sure the result will be a little less weight, and a smoother surface,
But what would the panel advice; another layer of antifouling on top of the old, or Hydrogommage first?

 

[Nick_H]

But the bill is more steep: 16500 + lift out, for the whole process.

Ouch! If the current antifoul isn't peeling then I wouldn't bother with stripping the old stuff.

 

[lanerboy]

if you search i think hurricane had all his removed before copper coating his boat and it caused no damage in the way it was removed some type of blasting it with mud of some description i think ?????

hopefully he may be along later to confirm this

 

[Hurricane]

Yes Bart

Here's the link to my report on our Coppercoat treatment.
http://www.ybw.com/forums/showthread.php?t=307750

You will see that this treatment (a wet slurry blasting) only removes the antifoul paint - even plastic fittings are undamaged.

If you are stripping the old A/F off, I would definately consider Coppercoat.

However, I agree with Nick - just wack on another coat of A/F

Our main reason for Coppercoat was because of a previous poor job and the boat had to be stripped anyway so it was almost a "no brainer" to put Coppercoat on.

I considered our whole process cheap - 5500 euros inc stripping and Coppercoat + lift
BA is a little bigger than JW so 6000/7000 euros ish - complete with Coppercoat
So 16500 for stripping and A/F seems a little expensive.

 

[Nick_H]

Bart, I had a quote for hull blasting to remove old antifoul earlier this year, and it was 35 euro/m2, from Bleumer shipyard at Baie des Anges. This may help you to sense check your quote, which seems very high to me. After blasting you need an epoxy coat to protect any voids which are opened up in the gel coat, then a primer, then 2 coats of a/f.

 

[Nick_H]

I considered our whole process cheap - 5500 euros inc stripping and Coppercoat + lift
BA is a little bigger than JW so 6000/7000 euros ish - complete with Coppercoat
So 16000 for stripping and A/F seems a little expensive.

That does confirm that Bart's quote is much too high, as Coppercoat needs 5 coats, on top of an epoxy primer, so more work than to strip and apply new antifoul.

If stripping the hull, and planning to keep the boat for a few years, then I agree it may make sense to Coppercoat it.

 

[BartW]

Bart, I had a quote for hull blasting to remove old antifoul earlier this year, and it was 35 euro/m2, from Bleumer shipyard at Baie des Anges. This may help you to sense check your quote, which seems very high to me. After blasting you need an epoxy coat to protect any voids which are opened up in the gel coat, then a primer, then 2 coats of a/f.

yes there is a epoxy coat included aswell,
and quotation states: 150m2 hull surface,

but agree, quote seems much to high compared to figures on here.
I'm not in a hurry, will confront the guy with these figures when I'll be there again,
I can still opt for his first basic antifouling quote anyway, which seems reasonable (lower then we payed in Italy)
I'm not sure if they can do copper coating in the area.

 

[Hurricane]

I was told by a paint manufacturer that our Princess 67 is 80sq metres of A/F area.
The Coppercoat agent worked it out to be 114 sq metres but I didn't mention the bathing platform overhang which he didn't take into account and would account for some of the difference.
The reality when we came to Coppercoating was something in between the two.

150 sq metres seems a little high for BA - IMO

There is a surface calculator on the Coppercoat website - maybe put BA's vital stats into it and see what comes out.

 

[MapisM]

Now I asked this yard their advice about taking off old layers of antifouling, and they gave me a quotation for “Hydrogommage”
Which is in simple words: Cutting off the old layers with pressurized water + abrasive material and then repairing eventual punctures, 2 layers of special primer, and 2 layers of antifouling

B, just a thought: it seems to me that maybe they had in mind with that quotation a hull in need of some osmosis repairs.
But even then, it's hard to tell how estensive such repairs should be without looking at the hull first.
Besides, I don't see any reason why they should have thought that BA needs such treatment.

Anyway, I agree with the suggestions you already got: either a good water pressure cleaning and a fresh a/f above the old one, or consider coppercoat if you really prefer to strip all the old stuff.
But I don't think that on such heavy boat you would get a meaningful performance improvement after such removal, anyhow.

 

[DAKA]

In order to prevent AF build up you should find a soft self eroding AF, in an ideal world it would be on top of hard (which I assume you have now), if the soft one goes completely you still have the hard as a fall back.

I use cruiser uno which is rated to 25knots, I deliberately go at max speed every now and then to find a fresh layer of self eroding AF.

The soft AF can be jet washed off, hence no build up of AF.

Seeing as slurry blasting got a mention I thought I best post details of my experience

My personal view is I would never have a grit/soda blast or paint stripper anywhere near my gel coat.

A few years ago at lift out a friend had his 1987 Fairline corniche at the side of my 1988 corniche.
He wanted me to join him for a slurry blast of 'gentle soda'.
I wasn't keen even when offered a two for one deal and declined.
My mate went ahead and I saw the damage the following weekend

Whole hull was riddled with small holes in the gel coat.
The whole boat had to be filled and epoxy coated.
At some stage a section of 1 ft by 2 ft on my bow had also been blasted.
It is unclear if
they started on the wrong boat.
they hit it by accident
they wanted to see if my hull would also be wrecked
they thought it was such a good job I would want mine done


My 'test' section was also covered with pin prick holes that I needed to fill.
I was pleased a small section had been tested as it confirmed to me that GRP shouldn't be grit blasted unless it needs an osmosis treatment.
A friend was then kind enough to clean my hull with an electric chisel, the old antifoul came off and left beautiful white shinny gelcoat with no visible signs of weakness.
It is clear that older boats have naturally occurring bubble holes deep within the gel coat that are created during the mixing. These bubbles are fine and will not cause a problem unless the Gel coat is overpolished with compound, over sanded or slurry/grit blasted.

The slurry blast had not made the holes but it had exposed voids that had been water tight for 15 years (moisture reading were very good).

The grass under the treated boat has still not grown back and turned into a bog for a while.

From my experience I would only have a slurry blast on a modern boat that had used a vacuum technique to mix the gel coat and so reduce the amount of bubbles.

If you read the professional sites they warn about this in a round about way " leaves a nice key finish ready for filling and epoxy coating " shouldnt the surface be ready for AF Primer ?

 

[BartW]

maybe they had in mind with that quotation a hull in need of some osmosis repairs.
But even then, it's hard to tell how estensive such repairs should be without looking at the hull first.

perhaps not osmosis repairs,
but in the quotation it say's 'masticage' cracks and holes

indeed they have no clue about the condition of the hull
so they counted for the worse lets say,
a boat covering was also included in the price,

but following all advice on here, I'm not going to do it,
I'll probably just add another layer of AF.

Daka, I'm not sure if self eroding AF is common practice on this type of boat,
I had two seasons with perfect AF,
and after reading many sad story's and having seen freightning pictures of barnacles on the shafts and props (mine are almost clean)
I'm a bit reluctant experimenting with this,

but actually as you say, the boat has a good layer of (old) antifoul,
even if the self eroding AF disappears quickly, there still is a protection underneath,

 

[Nick_H]

and after reading many sad story's and having seen freightning pictures of barnacles on the shafts and props (mine are almost clean)

Tell us more! What do you use?

 

[BartW]

Tell us more! What do you use?

I'm very very sorry Nick, the boat was AF two times in different yards in Italy, and I didn't asc what they used,
on one quotation they mentioned "international paint' no mentioning type nr,
both yards did it exactly the same way,

black AF on the hull (my request)
sort of white AF on flaps and P brackets and shafts
none (or collorless) paint on the props

here you can see the gear after the first season, but I must admid that the boat was in a river, fresh water for two months just before that.

I'm going to try to find out what they have used, but I assume its the standard product in Italy (?)

This season we also have almost no barnacles (except on the unprotected hilo lift mechanism)
inspected by myself after a dive.

I'll promose that I will make pictures during the next lift out, probably in april

 

[Hurricane]

perhaps not osmosis repairs,
but in the quotation it say's 'masticage' cracks and holes

indeed they have no clue about the condition of the hull
so they counted for the worse lets say,
a boat covering was also included in the price,

but following all advice on here, I'm not going to do it,
I'll probably just add another layer of AF.

Daka, I'm not sure if self eroding AF is common practice on this type of boat,
I had two seasons with perfect AF,
and after reading many sad story's and having seen freightning pictures of barnacles on the shafts and props (mine are almost clean)
I'm a bit reluctant experimenting with this,

but actually as you say, the boat has a good layer of (old) antifoul,
even if the self eroding AF disappears quickly, there still is a protection underneath,

Have you looked at International Micron 77?
All antifoul errodes but Micron 77 is designed for fast planing boats and errodes more than hard antifouls.

My problems were with Micron 66 (the previous version of the product)
It worked well in the water (apart from rubbing off on swimmers) but when we lifted a year later it all peeled - the local contractor and International then slapped Primacon and Micron 77 on the top thus making a complete mess - this was the reason I stripped the lot.

But I know of several who are happy with the newer Micron 77

 

[BartW]

Have you looked at International Micron 77?
All antifoul errodes but Micron 77 is designed for fast planing boats and errodes more than hard antifouls.

My problems were with Micron 66 (the previous version of the product)
It worked well in the water (apart from rubbing off on swimmers) but when we lifted a year later it all peeled - the local contractor and International then slapped Primacon and Micron 77 on the top thus making a complete mess - this was the reason I stripped the lot.

But I know of several who are happy with the newer Micron 77

yes I know (from here) that Micron 77 is the best
I'm just not sure that this is what I have.
the black stuff does rub off a bit when you shave it with your hand