DIY blasting - what are the cons?

[Refueler]

Why if the coppercoat hasn't worn through? Surely what you are saying is don't buy a second hand boat that is coppercoated because you can't be sure of the prep.

That is NOT what I read from AP's post.

 

[AntarcticPilot]

Why if the coppercoat hasn't worn through? Surely what you are saying is don't buy a second hand boat that is coppercoated because you can't be sure of the prep.

Coppercoat is very slightly porous, so if the gel coat was damaged you'd have to replace the Coppercoat BEFORE it was worn through.

Damage to gel coat is carefully avoided by professional blasting, so it would only be an issue for DIY work. Further, I'd expect damage to the gel coat to be made good before applying Coppercoat - say by applying an epoxy primer.

Coppercoat depends entirely on good preparation.

 

[dgadee]

Being in Scottieland, Coppercoat advise blasting in winter and waiting for warmer weather in early summer. Lets the hull dry out a bit and ensures correct weather for application. So it is obviously sensitive to application conditions.

 

[IanCC]

Coppercoat is very slightly porous, so if the gel coat was damaged you'd have to replace the Coppercoat BEFORE it was worn through.

Damage to gel coat is carefully avoided by professional blasting, so it would only be an issue for DIY work. Further, I'd expect damage to the gel coat to be made good before applying Coppercoat - say by applying an epoxy primer.

Coppercoat depends entirely on good preparation.

So how do you tell if you are buying a second hand, coppercoated, boat?

I appreciate responses, thank you.

 

[Refueler]

Being in Scottieland, Coppercoat advise blasting in winter and waiting for warmer weather in early summer. Lets the hull dry out a bit and ensures correct weather for application. So it is obviously sensitive to application conditions.

ALL coatings are sensitive to conditions .....

Coppercoat is using an epoxy resin base. Epoxy resin is recc'd to use in 15 C or higher ... so winter is not a good time for it anyway.

 

[Tranona]

So how do you tell if you are buying a second hand, coppercoated, boat?

I appreciate responses, thank you.

Failure usually manifests itself by poor adhesion and the coating coming off. It also may require refreshing by abrading with a Scotchbright pad from time to time if it starts to lose effectiveness. After typically 10 years+ it may need recoating which does not require removal of the old, just flatting down and re-application. So if it is still attached to the boat and you get an idea when it was applied you can make reasonable assumptions about its future life. GRP hulls are rarely a problem as any adhesion failure shows up pretty quickly after application. The real weakness is getting it to stick to cast iron keels because of the difficulty of getting the iron clean and free of impurities. Good blasting (not grinding) and immediate coating with epoxy is critical. On old corroded iron keels it may be sensible to use one of the long life (2-3 years) antifouls rather than Coppercoat.

 

[IanCC]

Failure usually manifests itself by poor adhesion and the coating coming off. It also may require refreshing by abrading with a Scotchbright pad from time to time if it starts to lose effectiveness. After typically 10 years+ it may need recoating which does not require removal of the old, just flatting down and re-application. So if it is still attached to the boat and you get an idea when it was applied you can make reasonable assumptions about its future life. GRP hulls are rarely a problem as any adhesion failure shows up pretty quickly after application. The real weakness is getting it to stick to cast iron keels because of the difficulty of getting the iron clean and free of impurities. Good blasting (not grinding) and immediate coating with epoxy is critical. On old corroded iron keels it may be sensible to use one of the long life (2-3 years) antifouls rather than Coppercoat.

Thanks, so if it's stuck it doesn't matter if the gwl coat was blasted through in places? Good to know.

 

[Tranona]

Thanks, so if it's stuck it doesn't matter if the gwl coat was blasted through in places? Good to know.

The blasting through the gel coat is a bit of a red herring. Nobody in their right mind would Coppercoat without filling and fairing. It is common for blasting to remove all or part of the gel coat on older boats with blistering damage from osmosis followed by filling and epoxy before applying any other coating.
The blastig throu

 

[IanCC]

The blasting through the gel coat is a bit of a red herring. Nobody in their right mind would Coppercoat without filling and fairing. It is common for blasting to remove all or part of the gel coat on older boats with blistering damage from osmosis followed by filling and epoxy before applying any other coating.
The blastig throu

Thanks for reply.
So, if like me, you have bought a second hand boat, coppercoated in 2016, which looks perfect and still works well. But the occasional (once every couple of years) fifty pence bit sized piece of coppercoat flakes off and all you can see underneath is supersmooth csm you shouldn't worry?

 

[greeny]

Thanks for reply.
So, if like me, you have bought a second hand boat, coppercoated in 2016, which looks perfect and still works well. But the occasional (once every couple of years) fifty pence bit sized piece of coppercoat flakes off and all you can see underneath is supersmooth csm you shouldn't worry?

Abrade and re coppercoat at the spot. If you had a real problem with adherance you would have known by now. You could apply some epoxy primer before the CC if you want.

 

[AntarcticPilot]

Thanks for reply.
So, if like me, you have bought a second hand boat, coppercoated in 2016, which looks perfect and still works well. But the occasional (once every couple of years) fifty pence bit sized piece of coppercoat flakes off and all you can see underneath is supersmooth csm you shouldn't worry?

Coppercoat shouldn't be flaking off; that sounds like bad preparation; mine has been in place for 10 years with no sign of flaking except on a cast iron keel, which even AMC will tell you is to be expected. I suspect it has been applied to a hull that wasn't allowed to dry before application. If you can see CSM that's bad! It that water can get into the laminate, wicked along the glass strands. If I were you I'd be looking at stripping back to GRP or gel coat, allowing the hull to dry out for several months and then coating with an epoxy coat followed by Coppercoat or antifoul of your choice.

 

[greeny]

Coppercoat shouldn't be flaking off; that sounds like bad preparation; mine has been in place for 10 years with no sign of flaking except on a cast iron keel, which even AMC will tell you is to be expected. I suspect it has been applied to a hull that wasn't allowed to dry before application. If you can see CSM that's bad! It that water can get into the laminate, wicked along the glass strands. If I were you I'd be looking at stripping back to GRP or gel coat, allowing the hull to dry out for several months and then coating with an epoxy coat followed by Coppercoat or antifoul of your choice.

Our opinions differ slightly. Depends how much you want to spend. and how sure you want to be.

 

[Elessar]

Two or three of us are planning to Coppercoat. One of the three suggested a diy approach. I am not enthusiastic having heard negatively from a friend (now sadly dead) who tried it but can't remember what he said.

What are the arguments against this approach if you have tried it? Skill level is my main concern given that to do it properly you would be working with powerful equipment on a thin get coat. I can see the positive - it could be cheap.

I use to own a blasting company and we did hundreds of Coppercoats.

Blasting is a skilled job. You will destroy gelcoat in less than half a second if you don’t know what you are doing.

If on the south coast I recommend Paul Shotton. He bought my farrow system blasting kit.

This is him doing my boat.

Watch how fast he has to move once the medium comes through. Hold still and your boat is ruined.

Also notice he leaves bits behind. He knows that if he goes back he will over blast and those little bits left are weakened and will sand off easily. If your blaster leaves it white he has over blasted.

 

[IanCC]

Coppercoat shouldn't be flaking off; that sounds like bad preparation; mine has been in place for 10 years with no sign of flaking except on a cast iron keel, which even AMC will tell you is to be expected. I suspect it has been applied to a hull that wasn't allowed to dry before application. If you can see CSM that's bad! It that water can get into the laminate, wicked along the glass strands. If I were you I'd be looking at stripping back to GRP or gel coat, allowing the hull to dry out for several months and then coating with an epoxy coat followed by Coppercoat or antifoul of your choice.

It had a couple of coats of epoxy prior to coppercoat but don't know if it's transparent.

 

[IanCC]

Coppercoat shouldn't be flaking off; that sounds like bad preparation; mine has been in place for 10 years with no sign of flaking except on a cast iron keel, which even AMC will tell you is to be expected. I suspect it has been applied to a hull that wasn't allowed to dry before application. If you can see CSM that's bad! It that water can get into the laminate, wicked along the glass strands. If I were you I'd be looking at stripping back to GRP or gel coat, allowing the hull to dry out for several months and then coating with an epoxy coat followed by Coppercoat or antifoul of your choice.

Seems a bit drastic for one 50p piece sized bit flaking off every couple of years, when it's been on 8 years.

 

[Tranona]

Seems a bit drastic for one 50p piece sized bit flaking off every couple of years, when it's been on 8 years.

Get a repair kit from AMC to do the patches. Looks a bit messy when you do it, but soon blends in when the boat goes back in the water. Photo shows patches on the keel of by Bavaria