5 ms·

This sort of anti-fouling is the holy grail. Copper based anti-fouling goes back centuries. The USS Constitution was copper bottomed in 1794. https://ussconst

This sort of anti-fouling is the holy grail. Copper based anti-fouling goes back centuries. The USS Constitution was copper bottomed in 1794. https://ussconstitutionmuseum.org/2015/08/12/copperbottomed/ https://ussconstitutionmuseum.org/2015/08/12/copperbottomed/ I remember an NPR story about using extremely hot peppers (adding capsaicin to bottom paint) to defoul. There was an anti-stick bottom paint but the trouble with it was that it wouldn't stick to hull. The trouble with copper is that it's a biocide, it kills. You're basically putting poison on the bottom of your bottom which leaches into the soil. Like tributyltin, copper's days are numbered. It's a hard problem. When I get back into sailing, it'll be dry sailing (put boat in water and haul out when done). BTW, bottom jobs are freaky expensive, $10,000 for a race bottom every year.

jerf 9y ago
"Copper = poison" is an oversimplification. Copper is also an important mineral, with 2mg/day a rough guideline for human consumption: https://ods.od.nih.gov/News/Copper.aspx https://ods.od.nih.gov/News/Copper.aspx (That number is at the very end, and that link also contains other interesting details about it.) It's not like lead, where basically every atom of it in you or the ecosystem is doing no good.
- derefr 9y ago
  That's humans. Are lower animals (and plants, and bacteria) the same, or is copper more like lead to them?
  - jerf 9y ago
    Well, considering our bodies all eventually end up feeding lower animals, plants, and bacteria, it can't be that fatal to them. Edit: If you want way too much detail in answer to your question: http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Environment.pdf http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Enviro... The most relevant bit is probably this bit on the bottom of page 5 and into page 6: "A study was performed to determine if pen-raised salmon were bioaccumulating copper from the antifouling coatings on the pens (20). Five pens were used - three of which were treated with cuprous oxide containing antifouling coatings and the other two were left untreated. The concentrations of copper in the muscle and liver of the salmon were measured, Figure 7. It was found that there was no correlation to pen treatments. It was speculated that the reason for this is the leaching of the copper was sufficiently slow such that the natural homeostasis of the fish and their detoxification processes are not compromised and that the leached Cu ion is reduced by complexation with organic and inorganic substances in the seawater." It isn't clear to me if these "pens" were enclosed or not; if they were then there really doesn't seem to be much reason to worry about copper antifouling. The article also says "Copper is an essential element required for normal growth in all plants and animals. As such, it is considered a normal constituent in the ecosystem in both soil and water where its presence is partially due to the metabolic by-products of plants and animals as previously discussed." The oceanic concentration of copper is given as 0.25ppb, which comes out to 340 million metric tons of copper in the oceans overall. I suspect that, like many do with "radiation", we tend to casually assume the normal concentration in the world is zero, thus rendering any human addition to the world an infinite-percent increase, but the natural world is messier than that. I thank you for your question, the research was interesting.
- SeanDav 9y ago
  Almost any compound is poisonous in high concentrations and/or doses. Even water can be deadly if one drinks too much over too short a period. https://en.wikipedia.org/wiki/Water_intoxication https://en.wikipedia.org/wiki/Water_intoxication
  - jerf 9y ago
    In the context of discussing putting something into the ocean, using the example of "lots of water" being toxic is somewhat... amusing. Given that copper is unambiguously a nutrient for life, I'd like to see a mechanism for how it would be excessively concentrated in places other than where it is directly being used before I get too concerned. In general, "in the ocean" is what I'd reach for as my example of where it is very difficult for something water-soluable to end up concentrating unexpectedly. Copper is something we put in multivitamins, on purpose. You can buy copper supplements for your cattle: https://www.jefferspet.com/products/copasure https://www.jefferspet.com/products/copasure You can read about how to rectify copper deficiencies in your garden soil, as well as the signs you've got too much: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/copper-for-the-garden.htm https://www.gardeningknowhow.com/garden-how-to/soil-fertiliz... "Copper = poison" is an oversimplification, in a way that "Lead = poison" isn't.
    - SeanDav 9y ago
      Since the subject of context has come up - in the context of water-living invertebrates, copper is poisonous in anything other than very low concentrations. This is why copper containing solutions are used to kill snail and slug infestations in aquariums, gardens and elsewhere. Not sure why there is any confusion about this. Any aquarium keeper for example, knows to avoid copper religiously if keeping inverts.
  - CalChris 9y ago
    Yes, tomatoes are poisonous (a relative of the nightshade) but you'd sooner drown in all the tomato juice you'd have to consume.
    - 9y ago
- hwillis 9y ago
  NB copper is pretty notorious for killing sea life. It's fine for fish and mammals, but a very small amount can kill all the algae and non-fish critters in an aquarium. Old timey copper submarine wires killed life for a fair radius on either side when they broke down. Most sea life just isn't capable of dealing with anything more than trace amounts of copper. When paint flakes or is scraped off the chips could have really negative local effects.
ohitsdom 9y ago
Any idea how long this coating would last on a ship's hull?
- CalChris 9y ago
  A competitive racer will get a bottom job once a year and dived (cleaned) every other week. It can last 2 or 3 years with regular diving. BTW, this is a great application for underwater drones both for big ships and littler sailboats.
chiph 9y ago
When you pull your boat out, make sure you rinse your bilge and motor (if any) before leaving to prevent the spread of Zebra Mussels. They've just arrived at the Central Texas lakes and it's only a matter of time before they become an expensive problem like they have elsewhere.
Grazester 9y ago
I know boat owners would be happy about this(not just sail boats). If it could last. Diving and scrubbing is a pain in the butt even when you dont mind diving.
bahjoite 9y ago
Indeed, copper sheathing [0] may have been used by the ancient Phoenicians and Carthaginians, but the first authenticated use seems to have been in 1758 [1]. [0]: https://en.wikipedia.org/wiki/Copper_sheathing https://en.wikipedia.org/wiki/Copper_sheathing [1]: https://darchive.mblwhoilibrary.org/bitstream/handle/1912/191/chapter%2011.pdf?sequence=20 https://darchive.mblwhoilibrary.org/bitstream/handle/1912/19... (pdf)
cma 9y ago
I've always wondered why they don't use some kind of peel-off adhesive layer. Would the mussels just penetrate through it and still cement to the hull? Even if you made it easy for them to cement to the adhered layer?

jerf 9y ago

"Copper = poison" is an oversimplification. Copper is also an important mineral, with 2mg/day a rough guideline for human consumption: https://ods.od.nih.gov/News/Copper.aspx https://ods.od.nih.gov/News/Copper.aspx (That number is at the very end, and that link also contains other interesting details about it.) It's not like lead, where basically every atom of it in you or the ecosystem is doing no good.

derefr 9y ago
That's humans. Are lower animals (and plants, and bacteria) the same, or is copper more like lead to them?
- jerf 9y ago
  Well, considering our bodies all eventually end up feeding lower animals, plants, and bacteria, it can't be that fatal to them. Edit: If you want way too much detail in answer to your question: http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Environment.pdf http://www.chemet.com/assets/1/6/Copper_and_the_Ocean_Enviro... The most relevant bit is probably this bit on the bottom of page 5 and into page 6: "A study was performed to determine if pen-raised salmon were bioaccumulating copper from the antifouling coatings on the pens (20). Five pens were used - three of which were treated with cuprous oxide containing antifouling coatings and the other two were left untreated. The concentrations of copper in the muscle and liver of the salmon were measured, Figure 7. It was found that there was no correlation to pen treatments. It was speculated that the reason for this is the leaching of the copper was sufficiently slow such that the natural homeostasis of the fish and their detoxification processes are not compromised and that the leached Cu ion is reduced by complexation with organic and inorganic substances in the seawater." It isn't clear to me if these "pens" were enclosed or not; if they were then there really doesn't seem to be much reason to worry about copper antifouling. The article also says "Copper is an essential element required for normal growth in all plants and animals. As such, it is considered a normal constituent in the ecosystem in both soil and water where its presence is partially due to the metabolic by-products of plants and animals as previously discussed." The oceanic concentration of copper is given as 0.25ppb, which comes out to 340 million metric tons of copper in the oceans overall. I suspect that, like many do with "radiation", we tend to casually assume the normal concentration in the world is zero, thus rendering any human addition to the world an infinite-percent increase, but the natural world is messier than that. I thank you for your question, the research was interesting.
SeanDav 9y ago
Almost any compound is poisonous in high concentrations and/or doses. Even water can be deadly if one drinks too much over too short a period. https://en.wikipedia.org/wiki/Water_intoxication https://en.wikipedia.org/wiki/Water_intoxication
- jerf 9y ago
  In the context of discussing putting something into the ocean, using the example of "lots of water" being toxic is somewhat... amusing. Given that copper is unambiguously a nutrient for life, I'd like to see a mechanism for how it would be excessively concentrated in places other than where it is directly being used before I get too concerned. In general, "in the ocean" is what I'd reach for as my example of where it is very difficult for something water-soluable to end up concentrating unexpectedly. Copper is something we put in multivitamins, on purpose. You can buy copper supplements for your cattle: https://www.jefferspet.com/products/copasure https://www.jefferspet.com/products/copasure You can read about how to rectify copper deficiencies in your garden soil, as well as the signs you've got too much: https://www.gardeningknowhow.com/garden-how-to/soil-fertilizers/copper-for-the-garden.htm https://www.gardeningknowhow.com/garden-how-to/soil-fertiliz... "Copper = poison" is an oversimplification, in a way that "Lead = poison" isn't.
  - SeanDav 9y ago
    Since the subject of context has come up - in the context of water-living invertebrates, copper is poisonous in anything other than very low concentrations. This is why copper containing solutions are used to kill snail and slug infestations in aquariums, gardens and elsewhere. Not sure why there is any confusion about this. Any aquarium keeper for example, knows to avoid copper religiously if keeping inverts.
- CalChris 9y ago
  Yes, tomatoes are poisonous (a relative of the nightshade) but you'd sooner drown in all the tomato juice you'd have to consume.
  - 9y ago
hwillis 9y ago
NB copper is pretty notorious for killing sea life. It's fine for fish and mammals, but a very small amount can kill all the algae and non-fish critters in an aquarium. Old timey copper submarine wires killed life for a fair radius on either side when they broke down. Most sea life just isn't capable of dealing with anything more than trace amounts of copper. When paint flakes or is scraped off the chips could have really negative local effects.

ohitsdom 9y ago

Any idea how long this coating would last on a ship's hull?

CalChris 9y ago
A competitive racer will get a bottom job once a year and dived (cleaned) every other week. It can last 2 or 3 years with regular diving. BTW, this is a great application for underwater drones both for big ships and littler sailboats.

chiph 9y ago

When you pull your boat out, make sure you rinse your bilge and motor (if any) before leaving to prevent the spread of Zebra Mussels. They've just arrived at the Central Texas lakes and it's only a matter of time before they become an expensive problem like they have elsewhere.

Grazester 9y ago

I know boat owners would be happy about this(not just sail boats). If it could last. Diving and scrubbing is a pain in the butt even when you dont mind diving.

bahjoite 9y ago

Indeed, copper sheathing [0] may have been used by the ancient Phoenicians and Carthaginians, but the first authenticated use seems to have been in 1758 [1]. [0]: https://en.wikipedia.org/wiki/Copper_sheathing https://en.wikipedia.org/wiki/Copper_sheathing [1]: https://darchive.mblwhoilibrary.org/bitstream/handle/1912/191/chapter%2011.pdf?sequence=20 https://darchive.mblwhoilibrary.org/bitstream/handle/1912/19... (pdf)

cma 9y ago

I've always wondered why they don't use some kind of peel-off adhesive layer. Would the mussels just penetrate through it and still cement to the hull? Even if you made it easy for them to cement to the adhered layer?