Copper Epoxy in a Mud Berth

[TetleyK]

I hope to be moving Naiad to a half-tide mud berth next season from her river mooring. My question is about her antifouling. Originally I applied Synergy but not particularly well and although the stuff stopped any growth very well it blistered and fell off. So I went to buy more only to find that the company had ceased trading.

So I bought and applied C-Guard and that not only went on and stayed on, but has done the job really well.

But that is in non-tidal waters where she is always afloat and Naiad will soon be in a mud berth.

The blurb for the Synergy product specifically mentioned that it should not be applied to hulls in mud berths as the Hydrogen Sulphide produced by organic matter in the mud reacted with the copper epoxy and rendered it black and useless.

So, my question is this, is that common to all epoxy copper antifouling or just Synergy?

So far my search around the InterWeb has revealed nothing about this, so over to you ladles and gentlespoons, perhaps one of you will know the answer.

Thanks.

 

[Kwik Decision]

We have our bilge keel boat on a semi tidal berth on the Hamble. Nothing seems to keep the keels clean, and I've tried coppercoat, international micron 350, and hemple tiger extra amongst others. They all keep the hull reasonably clean, but the bits that go in the mud end up covered with barnicles, which then get covered in soft sea squirts.
We get the boat lifted and scrubbed before our summer cruise, and this is much cheaper than paying the extra for an all tide berth...

 

[TetleyK]

We have our bilge keel boat on a semi tidal berth on the Hamble. Nothing seems to keep the keels clean, and I've tried coppercoat, international micron 350, and hemple tiger extra amongst others. They all keep the hull reasonably clean, but the bits that go in the mud end up covered with barnicles, which then get covered in soft sea squirts.
We get the boat lifted and scrubbed before our summer cruise, and this is much cheaper than paying the extra for an all tide berth...

Thanks for the reply.

I'm not so worried about the antifouling properties of the copper epoxy, Naiad is only 16ft 6" long with a centre plate, so she is very easily beached, leant over with a rope to the top of the mast and scrubbed.

I'm more concerned about the possible chemical reaction of the Hydrogen Sulphide the mud and the copper epoxy. Synergy were very specific about this for their product.

It might be that I just have to try it and see. At 16ft in length it is not expensive to slap a coat "normal" antifouling on if that becomes necessary.

 

[VicS]

Thanks for the reply.
I'm not so worried about the antifouling properties of the copper epoxy, Naiad is only 16ft 6" long with a centre plate, so she is very easily beached, leant over with a rope to the top of the mast and scrubbed.

I'm more concerned about the possible chemical reaction of the Hydrogen Sulphide the mud and the copper epoxy. Synergy were very specific about this for their product.

It might be that I just have to try it and see. At 16ft in length it is not expensive to slap a coat "normal" antifouling on if that becomes necessary.

I would think if a reaction occurs with one type of copper/ epoxy antifouling then it will occur with any other similar product. Perhaps the makers of C-Guard can help. There is a n enquiry form on their website.
I wonder what peoples experiences are with Coppercoat

OTOH perhaps your shallow draft hull will only create a shallow depression in the oxygenated top layers of the mud and not sink in far enough to be exposed to the hydrogen sulfide in the deeper anaerobic layers.

.

 

[TetleyK]

I would think if a reaction occurs with one type of copper/ epoxy antifouling then it will occur with any other similar product. Perhaps the makers of C-Guard can help. There is a n enquiry form on their website.
I wonder what peoples experiences are with Coppercoat

OTOH perhaps your shallow draft hull will only create a shallow depression in the oxygenated top layers of the mud and not sink in far enough to be exposed to the hydrogen sulfide in the deeper anaerobic layers.

.

I contacted Tony Grimes from C-Guard first but I guess he's either very busy or no longer with us after Covid. I hope the former.

Good point about the depth of penetration. (Moderators please note, that wasn't rude!)

 

[PCUK]

My steel 40 footer was on a mud berth in Gillingham marina for many years with a copperbot bottom. It did go black but still worked well for over 15 years.

 

[AntarcticPilot]

I think it depends on the exact composition of the mud! If it's an anoxic mud with a high organic content (the kind that stinks!), there will be the possibility of the copper being chemically degraded by reduction reactions.

If it's a sticky mud with a high clay content, then people have reported problems arising because the mud forms a layer over the antifoul, and then things grow on the mud!

A nice silty mud probably won't be a problem.

 

[TetleyK]

My steel 40 footer was on a mud berth in Gillingham marina for many years with a copperbot bottom. It did go black but still worked well for over 15 years.

Thanks, that's the practical experience I was looking for when I asked the question. I presume that the black copper sulphide also has antifouling properties.

 

[TetleyK]

I think it depends on the exact composition of the mud! If it's an anoxic mud with a high organic content (the kind that stinks!), there will be the possibility of the copper being chemically degraded by reduction reactions.

If it's a sticky mud with a high clay content, then people have reported problems arising because the mud forms a layer over the antifoul, and then things grow on the mud!

A nice silty mud probably won't be a problem.

I'm not sure what the mud in the half-tide berth is like. As it is on the East Coast I suspect that it's really sticky, gungy and possibly stinky. I guess I'll find out next year.

 

[AntarcticPilot]

I'm not sure what the mud in the half-tide berth is like. As it is on the East Coast I suspect that it's really sticky, gungy and possibly stinky. I guess I'll find out next year.

Mud - even in the East Coast - varies enormously. On the north coast of Norfolk, there's a lot of very mobile, silty mud - when studying Geology I was taken on a field trip to observe sedimentary processes in action there! Places like the Walton Backwaters, you get a black, very fine-grained mud in places - but a hundred yards further along you're on sand (e.g. Stone Point). The take home point is that "mud" as a generic term isn't helpful when it comes to advising on things like its effects on antifouling (of any kind). I've seen several posts on here from people in mud berths who don't antifoul at all - the mud itself stops things from adhering, and the motion through the water removes the mud. An annual clean is all they use.

So, horses for courses!

 

[TetleyK]

Mud - even in the East Coast - varies enormously. On the north coast of Norfolk, there's a lot of very mobile, silty mud - when studying Geology I was taken on a field trip to observe sedimentary processes in action there! Places like the Walton Backwaters, you get a black, very fine-grained mud in places - but a hundred yards further along you're on sand (e.g. Stone Point). The take home point is that "mud" as a generic term isn't helpful when it comes to advising on things like its effects on antifouling (of any kind). I've seen several posts on here from people in mud berths who don't antifoul at all - the mud itself stops things from adhering, and the motion through the water removes the mud. An annual clean is all they use.

So, horses for courses!

Going to be a case of suck stand see, I guess.

Still, my searches have discovered that copper sulphide was used as an antifouling, so it would seem that any H2S in the mud reacting with the metallic copper will not stop the antifouling properties. As for the mud preventing growth or otherwise, that would depend on factors beyond my control.

Should be an interesting first season back in tidal waters. Definitely looking forward to it.

 

[Hydrozoan]

... Still, my searches have discovered that copper sulphide was used as an antifouling, so it would seem that any H2S in the mud reacting with the metallic copper will not stop the antifouling properties. ...

A general theory about the toxicity of heavy metals in anoxic sediments posits that formation of their solid sulfides, having very low solubility, reduces their toxic effect compared with a similar level of total metal in oxic sediments - and that only if the sediment sulfide is ‘exhausted’ will the metals in the pore water become more bio-available and more toxic. One can readily see potential parallels with a copper antifoul in anoxic conditions.

(If you really want to look further into that, the theory is the basis of a procedure for assessing likely metal toxicity in anoxic sediments, involving simultaneous measurement of acid-extractable metal and sulfide: the so-called SEM-AVS approach - Simultaneously extracted metals/Acid-volatile sulfide - which I find has its own Wikipedia entry: Simultaneously extracted metals and acid-volatile sulfide - Wikipedia.)

FWIW, my own view is that you would be unwise to bank on the antifouling properties being unimpaired - but so much would depend on the specific conditions, the nature of the fouling organisms - which will be different anyway in a new and mud berth - and the way they interact with the antifoul etc. etc. that you will just have to wait and see. (No one with your best interests at heart would suggest sucking it!)

I’m not quite sure what your principal concern is - integrity of existing coating, colour or effectiveness - but I assume you will be able to ask your new ‘neighbours’ how they fare, and PCUK’s experience sounds promising unless blackening is a concern. Good luck!

 

[TetleyK]

snip...
I’m not quite sure what your principal concern is - integrity of existing coating, colour or effectiveness - but I assume you will be able to ask your new ‘neighbours’ how they fare, and PCUK’s experience sounds promising unless blackening is a concern. Good luck!

Basically, should I cover the copper epoxy (CE) with a "standard" antifouling before I go in the water or leave it for now. Colour is irrelevant as far as I'm concerned as I won't see it when I'm on board

If the experience of other CE sailors in mud berths showed that the CE was completely ineffective then I'd apply new antifouling before going back in the water. However, it does seem that it would be wise to leave Naiad with the CE and see what happens as there is so much variation in what might happen.

What is apparent is that the CE may well be fine but it doesn't look like it will fail completely.

Thanks.

 

[SandyP]

Hi, speaking theory only, your mileage may vary

The idea of using copper, in pipes too, is that it is toxic to many annoying critters. Toxic because they secrete acid and eat into to the copper, which then kills them

Copper sulphide is also broken down by these acids, consequently it should still be as toxic to such critters that secrete acids (ie to dissolve rock in order to attach themselves)

 

[TetleyK]

Hi, speaking theory only, your mileage may vary

The idea of using copper, in pipes too, is that it is toxic to many annoying critters. Toxic because they secrete acid and eat into to the copper, which then kills them

Copper sulphide is also broken down by these acids, consequently it should still be as toxic to such critters that secrete acids (ie to dissolve rock in order to attach themselves)

It would be really nice if the copper epoxy stayed effective, that stuff is expensive and has worked really well for me for the past 5 years. I don't really want to cover it with anything else, but the mud berth is calling...

 

[oldmanofthehills]

Our old boat was in a mud berth on the Somerset Axe. The Coppercoat worked fine except for small barnacles. Still seem fine at point of sale 11 years after application. In mud to thin to pour but too thick to plough as they say

Suggest you dont wreck it by overcoating with other stuff. Buff it up instead , though gently, and only overcoat it if it completely ceases to work.

I simply dont see how hydrogen sulphide might get through 2 or 3 layers of epoxy and cause harm to polyester or epoxy gel coat. Coppercoat turns brown in mud, not the lovely verdigris green of clear water applications. Just needs a scrub at start of season, and nothing seems to stop waterline weed.

Mud itself is pretty good at preventing growth anyway. In the previous 25 years on that mooring I only applied antifouling maybe six or 8 times. As hydrozoan says, H2S is poisonous to most organisms, so maybe thats the saving grace.

 

[Hydrozoan]

... As hydrozoan says, H2S is poisonous to most organisms, so maybe thats the saving grace.

Well I didn't really - but I don't disagree!

 

[AntarcticPilot]

As hydrozoan says, H2S is poisonous to most organisms, so maybe thats the saving grace.

Organisms includes people, so let's hope the concentration doesn't get too high

 

[TetleyK]

Organisms includes people, so let's hope the concentration doesn't get too high

I worked for an oil company in Kazakstan for a while and the oilfield there produced H2S. Only specially trained workers were allowed on the oilfield and then they had to carry respirators. Plebs like me had to stay well away, miles away in fact. H2S is dangerous stuff in those concentrations. Paralyses the breathing, so I'm told.

 

[TetleyK]

Our old boat was in a mud berth on the Somerset Axe. The Coppercoat worked fine except for small barnacles. Still seem fine at point of sale 11 years after application. In mud to thin to pour but too thick to plough as they say

Suggest you dont wreck it by overcoating with other stuff. Buff it up instead , though gently, and only overcoat it if it completely ceases to work.

I simply dont see how hydrogen sulphide might get through 2 or 3 layers of epoxy and cause harm to polyester or epoxy gel coat. Coppercoat turns brown in mud, not the lovely verdigris green of clear water applications. Just needs a scrub at start of season, and nothing seems to stop waterline weed.

Mud itself is pretty good at preventing growth anyway. In the previous 25 years on that mooring I only applied antifouling maybe six or 8 times. As hydrozoan says, H2S is poisonous to most organisms, so maybe thats the saving grace.

She a wooden boat so there's no danger of H2S damaging the gelcoat.

Thanks for the reply, you have pretty much confirmed what others have been saying. The copper epoxy is a nice shade of pale green right now as she is out of the water for the moment and where I have used sandpaper to remove any "limescale" it has come up pink. I'll give her a light sanding just before she goes in again.

Cheers.