Questions About Bottom Paint
- Thread starter cousineddy
- Start date
Yeah, pretty much. The hull didn’t have the hard wormy things tho. The prop did. Otherwise it was the same.
So in other words, the cuprous oxide in your anti fouling paint completely retarded the shelled animal growth while the bronze prop (actually naval brass) did not. Does that answer your question?
Just a touch of Oil of Olay every night and you'll look like a teenager again.
OK then, maybe not just a touch. Maybe a whole bucket every night but you'll be so glad you did.
Didn’t protect against slime, but protected against shells? The hull was brushed from the dock every 2 weeks. Tuff to brush the prop. So, inconclusive.
Not inconclusive at all. Copper is excellent at retarding higher forms like shelled animals and plants. The slime is algae and copper is less effective against that. Which is why paint manufacturers use secondary ingredients that interrupt the algae life cycle and disrupt photosynthesis. Naval brass is less effective than copper as far as anti fouling goes and of course, does not leach its constituent ingredients like copper or zinc-based anti fouling paints do. Therefore your prop had tube worm and barnacle fouling while your hull did not.
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The slime on your bronze prop is not what I would be concerned with. The "wormy things" on the prop are a concern and I don't think they are biological. A better photo would help and a good photos of the through hulls and the sacrificial anode would be helpful would also be helpful.
What kind of anode do you have on the shaft, zinc, aluminum or magnesium? What do the other bronze below the waterline fittings look like?
Given what I can see in the photo the "wormy things" are the result of galvanic corrosion in which the zinc in the prop is leaching out of the prop. This can be caused by a several issues, including poor wiring on the boat and poor wiring in the marina. The consequences of not dealing with this can result in very expensive damage, i.e, replacing the prop, replacing the strut, and replacing the thru-hulls. If you are uncertain about how to remediate this issue, I suggest you find a ABYC certified marine electrician or corrosion specialist to properly advise you.
Galvanic corrosion is caused by 2 dissimilar metals immersed in an electrolyte which are at different electrical potentials. One why to prevent it is to ensure that the metals are maintained at the same electrical potential. This can be done by bonding the metals together and providing an appropriate sacrificial anode.
Another avenue for galvanic corrosion is with the shore power connection and through the ground wire. A galvanic isolator is used to break the circuit and prevent galvanic corrosion.
This is not to be confused with electrolytic corrosion which is caused by 2 dissimilar metals being energized by an external source.
The more important point than whether this is electrolytic or galvanic corrosion is that either one is destructive and needs to be corrected to prevent expensive damage to the underwater metals.
Another avenue for galvanic corrosion is with the shore power connection and through the ground wire. A galvanic isolator is used to break the circuit and prevent galvanic corrosion.
This is not to be confused with electrolytic corrosion which is caused by 2 dissimilar metals being energized by an external source.
The more important point than whether this is electrolytic or galvanic corrosion is that either one is destructive and needs to be corrected to prevent expensive damage to the underwater metals.
You can zoom in to the photo of the prop to see the Anode. Not sure what it had, but replaced it with magnesium. It the boat still has factory wiring. Its in pretty good shape. There is definitely current in the marina water. Not allowed to swim. The thru hulls are faired into the hull, so all you can see is a hole. Those wormy things were material additions. After I sanded those off, the prop looked really good. No pits. Same with the shaft. The after photo is closest one I have to the prop.
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Look for reddish pink areas on the prop, they are a sign of the zinc being leached out.
Not sure where you are in MS? The picture looks like it may be salt or brackish water. Zinc would probably be a better choice than Magnesium.
@cousineddy By your belief that "dilution is the solution to pollution" then I guess it would be okay to dump radioactive waste into the ocean too? Maybe dioxin, PCBs, and other toxins? The oceans covers roughly 3/4 of the earth and contain about 352,670,000,000,000,000,000 gallons of water (according to NOAA) and contains virtually all of the types of nuclear isotopes except only a few transuranics. Would it be okay with you to dump all the wastes, including the spent fuel rods into the ocean? I am a nuclear engineer and would not argue that that is a good idea.
If you consider that most boats sit at a pier or mooring most of their life and the leaching occurs is a "relatively small" area it would seem reasonable that concentration, especially in the food chain, might occur. I don't have the scientific references but I am sure they exist to support that at least some toxins can accumulate in the sediment and be at higher concentrations near the hull. Yes, the concentration dissipates the further from the hull and may not accumulate as much in areas with large tidal swings but that would require "location by location" studies and probably is not going to happen.
Your "growth" on the prop is nothing compared to what we get in Beaufort SC. My hard bottom paint (Trinidad Pro) does a decent job of keeping the hard growth at bay and requires cleaning by a diver about every month from November to May or so. The Trinidad Pro does make it relatively easy to remove what small amount of hard growth does start. It does not keep the "mat" from growing if I don't sail it enough, especially where the sunlight can get to the hull. Somewhere is a balance between environmental concerns and recreational boaters.
@cousineddy By your belief that "dilution is the solution to pollution" then I guess it would be okay to dump radioactive waste into the ocean too? Maybe dioxin, PCBs, and other toxins? The oceans covers roughly 3/4 of the earth and contain about 352,670,000,000,000,000,000 gallons of water (according to NOAA) and contains virtually all of the types of nuclear isotopes except only a few transuranics. Would it be okay with you to dump all the wastes, including the spent fuel rods into the ocean? I am a nuclear engineer and would not argue that that is a good idea.
If you consider that most boats sit at a pier or mooring most of their life and the leaching occurs is a "relatively small" area it would seem reasonable that concentration, especially in the food chain, might occur. I don't have the scientific references but I am sure they exist to support that at least some toxins can accumulate in the sediment and be at higher concentrations near the hull. Yes, the concentration dissipates the further from the hull and may not accumulate as much in areas with large tidal swings but that would require "location by location" studies and probably is not going to happen.
Your "growth" on the prop is nothing compared to what we get in Beaufort SC. My hard bottom paint (Trinidad Pro) does a decent job of keeping the hard growth at bay and requires cleaning by a diver about every month from November to May or so. The Trinidad Pro does make it relatively easy to remove what small amount of hard growth does start. It does not keep the "mat" from growing if I don't sail it enough, especially where the sunlight can get to the hull. Somewhere is a balance between environmental concerns and recreational boaters.
I believe in clean air and water. But, my wife says I have “boat brain”. Its very frustrating in a race that the boat doesn’t do what you want and you get passed. In my mind, nasty bottom paint has no impact on the environment. Its just the thought of it like you stated. Like, it was hard for me to know that its OK to dump the sh!tter off shore. But, if you do the math, aint no thang. Like, say you have your tap water tested. Its all about the PPM that determines if its safe. I took a 500 level pollution control class in college. It was all about diluting. So, its a real thing, not a belief.
Whether you believe that anti fouling paint has an impact on the environment or not is irrelevant. It does and there have been many, many studies proving this. Here's one:
"The leaching of the toxic substances from the matrix of the paint causes toxic effects not only to the fouling organisms but also on other “non-target” biota."
The effects of a copper-based antifouling paint on mortality and enzymatic activity of a non-target marine organism
Antifouling paints are used on a wide range of underwater structures in order to protect them from the development of fouling organisms. The leaching …
Here's another:
"Here, we show that zinc pyrithione, Sea-Nine 211, KH101, and copper pyrithione (all commonly used anti fouling paint biocides) are much more toxic to sea urchins than... other chemicals."
Effects of new antifouling compounds on the development of sea urchin
Tributyltin oxide (TBTO) has been used worldwide in marine antifouling paints as a biocide for some time. However, it produced toxic effects, especial…
And yet another:
"The release of biocides, such as copper from antifouling coatings on vessel hulls represents a significant proportion of overall (copper) loading in those harbors and estuaries where substantial numbers of small craft or large vessels are berthed."
Measurement of copper release rates from antifouling paint under laboratory and in situ conditions: implications for loading estimation to marine water bodies
The release of biocides, such as copper (Cu), from antifouling (AF) coatings on vessel hulls represents a significant proportion of overall Cu loading…
I could go on and on. But why bother? You clearly aren't interested in facts.
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The extreme examples, i.e., dioxins, aside, the fundamental concept of the entire NPDES effluent permitting process relies on dilution in that all effluent limits are predicated on how discharges may affect water quality standards. In other words, dilution is a valid consideration in all state and Federal environmental air,water and waste control programs.
Protestation by internet cherry pickers notwithstanding, as a practical matter, the contribution of all recreational boat bottoms to water contamination in coastal areas is trivial.