Do barnacles prefer white antifoul?

[MissFitz]

I've been advised by a very knowledgeable local racer to use black or dark blue antifoul rather than white because barnacles prefer white. Can anyone vouch for this? (My boat has bright orange topsides which would go better with a white hull - but it has also been annoyingly prone to barnacles this year, so I'm keen to discourage the little critters.)

 

[SailSouth]

I was told, and I can't recall who by, that there is more of the nasty stuff that stops growth in the darker colours becase it's harder to hide in a white-pigmented paint.

I have no idea if that is true.

White is certainly better if you want to see if your bottom is clean as slime is easier to spot through the water.

I was white but now blue but they are different paints from international so can't really compare fairly.

 

[Seajet]

I have always used white antifoul; as my club launches and recovers all the cruisers together over a 3-day period we all gather around and discuss visible results at end of season, which is quite useful as most of us are in the same locations and conditions.

I'd always used International Micron or Cruiser / Uno, but the year before last the results with Uno were so spectacularly poor I switched to Blakes, Now Hempel, Tiger which worked very well indeed.

No particular difference between the club boats re paints or colours re barnacles - we all had some but not a huge amount, but mine had hardly any weed - so it seems to be more to do with the type of paint, and maybe local conditions.

 

[dom]

For racing, I'd have thought slime wld be a problem in the S UK before barnacles. Barnacles are different to weed and other creatures in that they drill into the a/f, as opposed to growing on it, thereby rendering its ablative characteristics somewhat redundant.

An International chap told me that for this reason their paints encapsulate poisons held within the paint. The barnacle drills in, ingests the poison and that's the end of him. Bit gory really :ambivalence:

Anyhow, FWIW I use Int Micron-? in the Solent, get a tiny bit of slime, but zero barnacles.

 

[lpdsn]

White has an advantage with hard racing antifoul as it is more obvious when a scrub is necessary.

I've not seen anything definitive that says colour makes any difference.

 

[wully1]

I was told, and I can't recall who by, that there is more of the nasty stuff that stops growth in the darker colours becase it's harder to hide in a white-pigmented paint.

I have no idea if that is true.

I believe you are correct - Most white antifouled boats seem to dry out with a greenish tinge from the copper?

 

[Hydrozoan]

For racing, I'd have thought slime wld be a problem in the S UK before barnacles. Barnacles are different to weed and other creatures in that they drill into the a/f, as opposed to growing on it, thereby rendering its ablative characteristics somewhat redundant.

An International chap told me that for this reason their paints encapsulate poisons held within the paint. The barnacle drills in, ingests the poison and that's the end of him. Bit gory really :ambivalence:

Anyhow, FWIW I use Int Micron-? in the Solent, get a tiny bit of slime, but zero barnacles.

I was under the impression that barnacles attached by adhesive action, and did not 'drill' into the substrate. See here for an account of the adhesive process: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0068085

 

[RAI]

Some say that for creatures that like light (weeds etc.), a dark surface is less attractive.
Personally I always apply two coats of different colours. The contrast with the previous layer allows one to ensure continuous coverage. The top coat can be of the preferred colour.
In the case of ablative anti-fouling, the slow appearance of the undercoat cover is fair warning of the need for another coat.

 

[lpdsn]

I was under the impression that barnacles attached by adhesive action, and did not 'drill' into the substrate. See here for an account of the adhesive process: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0068085

I suspect you know more about this that probably than the rest of us put together so I'll not doubt your statement, but when you remove barnacles it does always appear that they've got through the anti-foul to either the gel coat or keel. And it doesn't appear that it's the removing of the barnacles that takes off the anti-foul. Is it because the barnacles end up dining on the paint?

 

[dom]

I was under the impression that barnacles attached by adhesive action, and did not 'drill' into the substrate. See here for an account of the adhesive process: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0068085

Very interesting link and well well beyond my barnacle pay grade! Still, it’s what an Akza Nobel bod told me, so possibly some nuances in terminology here.

Either way, in the Solent at least, ‘Micron-latest’ seems to hold back these nasty critters, which whatever their gluing system are an ‘orrible’ job to remove. We of course use different lingo in Dublin but that’s not allowed here

 

[Tim O]

Im an ecologist and I used to teach marine biology to A level students in field centres and these are some of the fcats about barnacles that we used to pass on which are backed up in the article referenced above:

Barnacles are a type of crustacean - related to crabs, lobsters and shrimps, but which have become adapted through evolution to a sedentary lifestyle. As a larval form (called a cyprid larva) they are mobile in the zooplankton - the tiny animals drifting at the mercy of ocean currents. At a certain stage in their lives, within the first year i believe, they settle on solid surfaces in the sea - rocks, wood, boat hulls - whatever they happen to find where the currents have taken them - this is for most UK species always within the intertidal zone. As far as I am aware there is very little evidence that they are choosy in terms of the substrate they settle on, either by colour or other features.

They secrete an adhesive substance from highly-modified antennae which they use to stick themselves to the substrate...as the article says though, they explore around a bit before selecting a final site to settle and stick permanently. There is some evidence that they choose to settle near adults of their own species which they can detect by chemical means - obviously if adults are surviving in a location it must be an ok place to live!....they also try to maintain a slight distnc from other larvae of their own species when they settle to allow space for growth, though if cyprid settlement is particularly dense that year they have no choice but to settle literally side by side. As they grow, then those who grow faster and get more food simply crowd out the weaker ones. Their bodies then metamorphose with the shell plates becoming hardened by secretion of calcium carbonate.

In terms of feeding...firstly...they do not "eat" the antifoul directly in any way- they filter feed using their legs which now become highly-modified feathery appendages used to catch microscopic organic particles and plankton from the water. I presume any effect of the toxins in the antifoul is by absorption through the surface in contact with the paint.

I am not aware that they "drill" into the paint surface in any deliberate way, though as their shell plates grow there could possibly be some apparent scraping away of the paint.

In essence, barnacles are standing on their heads waving their legs in the water - we used to get the students mimicing this on the beach for a laugh - 30 teenagers doing this is highly entertaining.

Further fascinating facts about barnacles - in terms of reproduction they are unusual in that unlike many marine invertebrates which simply release eggs and sperm into the sea and hope for the best, barnacles actually undertake "proper" sex. They have the disadvantage though of being stuck in one place....as they cant move to a mate, they have evolved long extendable tube penises with which they can reach around to find another barnacle to fertilise.....we always taught that relative to body size they have the longest penis of any animal and that if they were humans it would be equivalent in length to Nelson's Column.

The students were particularly interested in that fact for some reason.

Fascinating creatures see...even if they are annoying! Isn't nature amazing!

 

[Tim O]

btw - annual variations in numbers of barnacles on your hull are far more likely to do with factors that affect overall breeding success and the currents which bring the larvae to where your boat is than any choice of colour paint i imagine - it could also be due to things like whether your boat happened to be in or out of the water during the brief period when peak larval settlement occurs
...

 

[lpdsn]

They secrete an adhesive substance from highly-modified antennae which they use to stick themselves to the substrate...as the article says though, they explore around a bit before selecting a final site to settle and stick permanently. There is some evidence that they choose to settle near adults of their own species which they can detect by chemical means - obviously if adults are surviving in a location it must be an ok place to live!....they also try to maintain a slight distnc from other larvae of their own species when they settle to allow space for growth, though if cyprid settlement is particularly dense that year they have no choice but to settle literally side by side.

Thanks for that informative post.

I wonder whether there would be any avenues that could be explored to use these chemical means to drive them off or to cause them to attach to some sacrificial item hung over the side, which could then be cunningly removed just when they think they're safe. I'm sure the paint manufacturers have already thought of this so I'm just curious about people's thoughts really.

 

[Hydrozoan]

I suspect you know more about this that probably than the rest of us put together so I'll not doubt your statement, but when you remove barnacles it does always appear that they've got through the anti-foul to either the gel coat or keel. And it doesn't appear that it's the removing of the barnacles that takes off the anti-foul. Is it because the barnacles end up dining on the paint?

I don’t know, but the adhesive is a proteinaceous material and may (for example) bind with the copper to some extent, and perhaps soften/solubilize the paint matrix – and as Tim O say, the plates of the shell may wear it away round the edges.

But it is pretty strong adhesive, so it may simply pull away the paint by adhering more strongly to it than the paint does to the hull - though I accept that does not accord with your thought that it isn't their removal that takes off the paint!

... I presume any effect of the toxins in the antifoul is by absorption through the surface in contact with the paint. ...

And/or by taking in dissolved copper from the water close to the paint as they filter it, as it will have a slightly elevated dissolved Cu concentration compared to the ‘bulk’ water further away from the surface.

 

[lpdsn]

But it is pretty strong adhesive, so it may simply pull away the paint by adhering more strongly to it than the paint does to the hull - though I accept that does not accord with your thought that it isn't their removal that takes off the paint!

I've not exactly carried out any systematic observations, so it's just what I saw in one particular year when I had a lot of barnacles on the hull. I removed the barnacles with a flat-bladed screwdriver. I then dissolved the left over ring with descaler. No signs of the screwdriver directly affecting the paint, or at least not on a regular basis, and I didn't remember any signs of paint attached to the squishy thing inside, but they seem to have worked all the way through a few years of anti-foul and partly through the primer to the gel coat. Hence the initial impression (before this thread) that they burrowed into the paint.

 

[Tim O]

I've not exactly carried out any systematic observations, so it's just what I saw in one particular year when I had a lot of barnacles on the hull. I removed the barnacles with a flat-bladed screwdriver. I then dissolved the left over ring with descaler. No signs of the screwdriver directly affecting the paint, or at least not on a regular basis, and I didn't remember any signs of paint attached to the squishy thing inside, but they seem to have worked all the way through a few years of anti-foul and partly through the primer to the gel coat. Hence the initial impression (before this thread) that they burrowed into the paint.

Its not impossible that they could make slight movements of the shell back and forth which could grind down slightly into the substrate - limpets for instance do the dame to ensure a very tight fit of their shells against the rock to prevent desiccatin - on soft rocks they actually grind a depression ring into the rock

 

[William_H]

Thanks Tim O for the detail on barnacles. I thought I got barnacles on my hull but perhaps what I get are limpets. They are conical shells that are very firmly attached to the antifouling and yes when I smash them off they take the paint with them.
I got some yesterday while swimming under the boat and being less than a week old could be removed with a finger insulated with rag. However mostly even after 2 weeks I need a metal scraper to remove them. They certainly don't mind growing on dark blue A/F.
As you can see I am a bit obsessive about clean bottom but also swim around and under the little boat for pleasure several times per week. You might also perceive that water is relatively warm. A/F lasts about 6 weeks before slime is wiped off and paint itself is getting wiped off after 3 months or so. But no I don't believe a/f colour determines barnacle growth. olewill

 

[Tim O]

Barnacles have similar shaped conical appearance to limpets but their "shell" (technically it is an exoskeleton made up of several sections or plates whereas a limpet being a mollusc is one single-piece shell) has various plates - usually arranged as an outer ring round a central area which actually opens up to allow the feeding appendages to emerge. You can usually see joints between the plates of barnacle shells though these can fuse and be less obvious as they age...but the central plates always show a joint as they open up daily

 

[Hydrozoan]

Its not impossible that they could make slight movements of the shell back and forth which could grind down slightly into the substrate - limpets for instance do the dame to ensure a very tight fit of their shells against the rock to prevent desiccatin - on soft rocks they actually grind a depression ring into the rock

Sure, but limpets as you know are very different animals, having a single shell and attaching - and moving around quite some distance, and grinding their shell as you describe - using a muscular foot, not sticking to the substrate using adhesive on their head. I’m not saying that barnacles might not do something broadly similar with their (4 or 5 separate) plates – but it might also be a mistake to assume that they do. I have found some evidence that their plates may mimic groves and ridges in the substrate because the secreted plate material follows its contours, rather than by virtue of ‘abrasive matching’, but in a fairly old paper (https://www.journals.uchicago.edu/doi/abs/10.2307/1538243?journalCode=bbl).

There is so much scientific literature on barnacle adhesion that the best way to look for an answer to lpdsn’s observation would be to find a thorough, recent review – though any such review might well be behind a paywall. But perhaps a more thorough Googling might just turn up trumps!

 

[Portofino]

Interesting thread
The professionals in the yard in the Med - South of France anecdotally report black and the darker AF works best .
So not really sure of the science ,like a lemming we just follow suit blindly.It seems to work the best when boats are lifted .
Realise there’s many variables,eg sunny side , useage and water temp etc etc .

Returning to the sub thread on barnacles,
Take a look at the image below please .
On my boat barnacles do Infact take a chunk ,halo effect of paint out when chipped off with a scraper or acid HCL dissolved off .
This will be areas that wet with the constant lapping of the water ,the white stripe .Supposed to be above the waterline in theory but support s barnacles.
Although the pics taken after re antifoul , the barnacles are never found on the black AF .Buts that’s a different issue ,more like at least it worked .

Obviously this stripe is not anitfouled that’s not the abservation here .
What we are seeing is a halo removal of the paint by the rim edge of the shell .

https://imgur.com/a/lLBtw

Last year a neighbour was restoring a white Grand Banks in the yard .I borrowed some of his white marine paint and used a tiny children’s paint brush to touch up those halos - add back some white paint .

So it could be argued the little 8arsteds are actually “ drilling “ down into the paint ,or more like the rim ( not the head inside ) of the shell is abraded the paint , or as it grows adds more secretions a chemical reaction occurs and removes the paint ?