Coppercoat + Blisters?

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welkman

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The boat I have recently purchased was surveyed 3 years ago, and in the survey the hull laminate was found to be remarkably dry. After the survey coppercoat antifouling was applied to the hull, so this coating is now 3 years old.

I have got the boat back home and had her craned ashore for the winter. When inspecting the hull after the boat was brought ashore, I found it to be covered with a number of blisters of varying size from about 5-15mm in diameter, many of which release vinegar-like fluid if burst.

I would find it very surprising if the blisters are osmotic and deep into the laminate, as the hull was found to be virtually dry 3 years ago, so my initial instinct is that they may well be at the interface between the coppercoat and the gelcoat, indicating that the coating has failed. (the coppercoat was not applied professionally).

Has anyone had a similar experience with coppercoat? Does anyone have any suggestions for investigating the problem further to come up with a conclusive diagnosis? Lastly, has anyone had any experience of stripping coppercoat should it become necessary, what is the best method to use?
 
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many of which release vinegar-like fluid if burst.

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I understand this is a characteristic of osmosis blisters - when the boat was surveyed had it been out of the water for a long time? - It may just be that it was taken out regularly and this is now apparent after three years in the water?
Anyway, you will get a lot of differing views on Osmosis, but a boat has never sunk from it, and unless very bad it is usually OK to leave well alone.
 
Open one up and have a look with a magnifying glass, has the blister formed between the gelcoat and the copperbot was the boat put back in the water before the copperbot had properly gone off
 
By the looks of things the Copperbot was done at the same time as the (very amature) paint job, so by the looks of things the copperbot was applied by an amature as well.
 
We had some work done on our Beneteau and a section of CopperCoat had to be re-done .. They insisted that it cured for a week before putting it back in the water again .. Epoxy that has not cured properly will pick up water .. You also have to make sure your preparation is good .. All traces of old antifouling must be removed .. Hope it all turns out ok .. /forums/images/graemlins/smile.gif
 
It is my understanding (I was going to use the product) that coppercoat/bot/or whatever must be applied to either a new hull or to fresh epoxy and never to old gel coat maybe this is the problem.
 
Conclusion is:

I am a victim of a seriously dodgy surveyor! The boat does have osmosis and the opinion of the survey today is that it had it 3 years ago as well!

Im not too dishartened though as I love the boat and it will be getting striped and blasted at the end of next season!

Coppercoat is doing its job well.

Thanks

James
 
I understood that copperbot etc although an epoxy based treatment against fouling needs to be applied over an epoxy treated hull, an aquaintance in france needed to remove copperbot etc from his westerly konsort because of a reaction with his previous coating, not a job he would ever repeat!!!! Grit blast may not be necessary if you are having the osmosis treated when the hull will probably be 'planed' prior to blasting and drying out. good luck, I copperbottomed in August and my catamaran not gone in water yet.
 
My understanding is that a hull suffering from 'osmosis' can show a dryish reading on a moisture meter if it has been out of the water for a while. Hugo de plesis (?) and others have written a lot about this, much of which has been published in PBO.

Many of the early epoxy treatments failed due their application over what were thought to be dry hulls.

The recommended treatment is now for the gelcoat to be peeled and the offending chemicals causing osmosis washed out with a combination of steam and vacuum.

Only then is the application of epoxy likely to fix the problem.


Mind you, many people are of the opinion that none of this matters as osmosis can be managed for an indefinite period of time and only comes into play as a negotiating point when you want to sell the boat.
 
I think im looking at gel stripping in two seasons time as im looking at the boat as a long term investment. I am also hoping to do the jester azores challenge in 2012, so It will be good to sort it by then! The boat was about 5k less than expected anyway - so no great loss. I am thinking of doing the osmosis job myself with the assistance of a surveyor so it could be cheaper than 'getting it done' at around 1500 - 2000 pounds. Might save a bit on the VAT as well now.
 
Just a quick account of what happen to our Westerly. We had her gelcoat removed, re-epoxied (Blakes) and then coppercoated. This was done by a Blakes approved centre which was also a Coppercoat approved agent, work was done inside sheds. After 12months blisters were discovered over the hull. I did a PH test to find the liquid behind the blisters was alkaline, which was down to amine between the 1st and 2nd coats of blakes epoxy. Blakes data sheets state an upper limit of 65% humidity - the coats were put on at 64%. The whole work had to be done again under warranty and she went back afloat last week. Blakes won't guarantee the surface of their epoxy if the next coat is anything other than a Blakes product. One last thing , we were in southern France when we discovered the blisters en route to the Med. and had to be road transported back to get the warranty work carried out.
 
Checked with surveyor and fellow science teaching staff today, seems the theory behind vaporising glycol and styrenes under a vacuum and lower heat seems sound and proven. The only issue is that it is, apparently, very hard to get right.

Should this put me off the HOTVAC system?
 
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