Brown water line stains

[toad]

Ok so I know how to remove it but what is it ? I notice that med boats don't seem to suffer from it and south coast boat not so bad as east coast boats. Coloured boats and painted boats seem pretty resistant. So what is it with white fiberglass and the east coast ? And while I am in question mode when you put the acid on where does the stain go, you cant wipe it of or see it running down the hull it just vanishes like magic.

 

[VicS]

while I am in question mode when you put the acid on where does the stain go, you cant wipe it of or see it running down the hull it just vanishes like magic.

It just vanishes like magic. Isn't science wonderful?

 

[wiggy]

it just vanishes like magic.

Well durr, it is magic obviously.

 

[toad]

So no one knows what the brown stuff is then. I shall have to consult a witch or Webby.

 

[VicS]

So no one knows what the brown stuff is then. I shall have to consult a witch or Webby.

I had always assumed that brown waterline stains were due to decomposed organic matter absorbed onto a carbonate scale formed in the splash zone. However the fact that there are removed so effectively by oxalic acid and in particular if the brown colour totally vanishes makes me think they may be due to red iron oxide. ie similar to rust stains. Unfortunately no longer in a position to investigate and test.

maybe there is iron in decomposed organic matter ......... Dead blood cells, which contain iron as everyone is aware, leave the body along with other solid waste ........ and perhaps eventually find their way onto your water line.

 

[johnalison]

I think it is oily materials that cause yellow and brown stains. I have sailed last year down the Channel and back without picking up any coloration, but I know that as soon as I go through Holland and parts of the Baltic this year I will pick up the usual stain. Many areas have a scum of brown muck which sticks to the waterline. I don't think ordinary mud causes trouble, but fishing harbours are always messy.

 

[johnalison]

maybe there is iron in decomposed organic matter ......... Dead blood cells, which contain iron as everyone is aware, leave the body along with other solid waste ........ and perhaps eventually find their way onto your water line.

The iron in the form of haemoglobin in blood is normally contained within the cells and shouldn't stain unless the cells burst. This will happen when they are exposed to a hypotonic medium, but won't in seawater. This is why you should always rinse blood stains with salt water and not fresh.

 

[VicS]

The iron in the form of haemoglobin in blood is normally contained within the cells and shouldn't stain unless the cells burst. This will happen when they are exposed to a hypotonic medium, but won't in seawater. This is why you should always rinse blood stains with salt water and not fresh.

So you are saying the brown colour of poo is not due to iron form broken down haemoglobin. Thats that theory blown out of the water then.

 

[Hydrozoan]

Oxalic acid is very effective in removing iron stains, not only because it is an acid (and a relatively strong one, for an organic acid) but also because it strongly complexes iron. But its complexing ability and acidity will also aid in dissolving carbonate scale.

I have wondered if brown waterline staining might be a consequence of humic and fulvic acids, but if so it is difficult to understand why oxalic acid should be so effective. A similar argument also applies to the notion that the staining is a consequence of oil.

So Vic’s theory of iron seems most likely, but without analysis it’s a puzzle nonetheless.

PS An alternative possibility is that the staining is a result of organic substances (humic/fulvic acids, oil) adsorbed onto carbonate scale, and that the oxalic acid works primarily by dissolving the scale, rather than by complexing (and thus 'bleaching') the iron.

 

[alan_d]

So you are saying the brown colour of poo is not due to iron form broken down haemoglobin. Thats that theory blown out of the water then.

Due to bile pigments secreted by the liver. Some of that pigment is indeed derived from the breakdown of haem from old blood cells. Don't think that it has anything to do with waterline stains, though.

 

[Hydrozoan]

The sea surface microlayer (SML), the topmost 1mm, concentrates pretty much everything in seawater, so perhaps the origin of the brown colour differs from place to place and time to time, and adsorption on scale is the only the common factor. (Why brown? Well, most of the potential culprits – oils, natural organics, iron, colloidal silt – are brown or become brown when oxidised.)

But one other thing occurs to me: might Phaeocystis algae be often involved? These have a free swimming and a gelatinous colonial form, and breakup of the latter after blooms can produce large quantities of white foam, which turns brown – simply through its oxidation, I presume. (Perhaps it also binds iron – I vaguely recall elevated zinc levels being reported after a bloom.)

Even if foam is not evident locally – high banks can form in bad nuisance blooms – Phaeocystis will presumably contribute a lot of material to the SML during the summer. Moreover, the exudate is antibiotic so it may not be broken down very quickly by bacterial attack.

It may be fanciful to attribute a portion of the problem to just one alga, but I think that (i) its distribution may match to some extent the N Sea>S Coast>Med pattern mentioned, and (ii) it is at times a major phytoplankton component – and, perhaps, a disproportionate contributor to the SML.

Anyway, another speculative suggestion for the pot.

 

[toad]

Well Hydrozoan that seems a likely situation, I notice that it is worse on the splash zone towards the front third of the boat. It also seems to occur once the weather warms up. I did wonder whether run of from the fields had anything to do with it as it seems worse in estuary's.

 

[Heckler]

I'm

I had always assumed that brown waterline stains were due to decomposed organic matter absorbed onto a carbonate scale formed in the splash zone. However the fact that there are removed so effectively by oxalic acid and in particular if the brown colour totally vanishes makes me think they may be due to red iron oxide. ie similar to rust stains. Unfortunately no longer in a position to investigate and test.

maybe there is iron in decomposed organic matter ......... Dead blood cells, which contain iron as everyone is aware, leave the body along with other solid waste ........ and perhaps eventually find their way onto your water line.

I always believed that it was discoloration from peat juices in the water. My boat came from Scotland, it had a decent brown beard stain. Oxalic acid sorted it. The next year in Pwllheli it appeared a little bit but again oxalic acid sorted it. Swmbo used, uses Autoglym which I believe leaves a resin coat which stays shiny, perhaps fills micro holes in the gel? No more brown stains since.
S

 

[Heckler]

The sea surface microlayer (SML), the topmost 1mm, concentrates pretty much everything in seawater, so perhaps the origin of the brown colour differs from place to place and time to time, and adsorption on scale is the only the common factor. (Why brown? Well, most of the potential culprits – oils, natural organics, iron, colloidal silt – are brown or become brown when oxidised.)

But one other thing occurs to me: might Phaeocystis algae be often involved? These have a free swimming and a gelatinous colonial form, and breakup of the latter after blooms can produce large quantities of white foam, which turns brown – simply through its oxidation, I presume. (Perhaps it also binds iron – I vaguely recall elevated zinc levels being reported after a bloom.)

Even if foam is not evident locally – high banks can form in bad nuisance blooms – Phaeocystis will presumably contribute a lot of material to the SML during the summer. Moreover, the exudate is antibiotic so it may not be broken down very quickly by bacterial attack.

It may be fanciful to attribute a portion of the problem to just one alga, but I think that (i) its distribution may match to some extent the N Sea>S Coast>Med pattern mentioned, and (ii) it is at times a major phytoplankton component – and, perhaps, a disproportionate contributor to the SML.

Anyway, another speculative suggestion for the pot.

Phew! sound like my PhD daughter, basis for a paper?
S

 

[sailorman]

I'm
I always believed that it was discoloration from peat juices in the water. My boat came from Scotland, it had a decent brown beard stain. Oxalic acid sorted it. The next year in Pwllheli it appeared a little bit but again oxalic acid sorted it. Swmbo used, uses Autoglym which I believe leaves a resin coat which stays shiny, perhaps fills micro holes in the gel? No more brown stains since.
S

The worst staining i have experienced was just 2 days in The North Holland canal, its just like tea with no milk. teak cleaner sorted it a few days later

 

[Reptile Smile]

We don't have nearly enough 'why is poo brown'-type threads. Good job, all round..!

 

[Hydrozoan]

Well Hydrozoan that seems a likely situation, I notice that it is worse on the splash zone towards the front third of the boat. It also seems to occur once the weather warms up. I did wonder whether run of from the fields had anything to do with it as it seems worse in estuary's.

Thanks. Whatever the brown stuff is, it’s going to be worse at the bows as they get more splash from the undisturbed SML, and rub-off from mooring buoys coated with it. Occurring when the weather warms up is some evidence for Phaeocystis, but the SML itself will be better established when the water is calmer, with more organic matter from algal growth generally. Being worse in estuaries could apply to many causes – e.g. silt and hydrocarbons will tend to be higher there.

But your point about run-off is moot, as nitrogen from rivers encourages Phaeocystis colony blooms. For example, a recent study of the Southern North Sea modelled the present-day and a reconstructed situation without human nutrient inputs. It found that Phaeocystis colonies (i) reached undesirable levels only under present-day conditions, and (ii) are favoured by rain increasing nitrogen input from rivers. (http://www.jpi-oceans.eu/imis?module=ref&refid=241400)

Fingering Phaeocystis is speculative, but such evidence - and an awareness of the amount of brown foam that can occur on beaches after blooms - makes it IMO a plausible cause in some locations at least.

... basis for a paper? ...

In addition to Vic’s point about investigation of iron in the stains, it could be interesting to seek a chemical ‘marker’ of the Phaecocystis colony gel and - if there were a suitable one - to then look for it in boat stains. I cannot somehow see it getting funding, however .

 

[adamstjohn]

I use oxalic acid and wallpaper paste to good effect however still have some staining that wont budge, think its in the tiny gel coat holes, really bugs me having it there. Its an old hull, a hummingbird 30 based on an Elizabethan 30, so is a substantial build. Anybody got any ideas? Think I need a liquid to penetrate it. Tried polishing compound but that hasn't touched it . Cheers.

 

[Hydrozoan]

I've never tried the oxalic acid / wallpaper paste method as I don't get much brown staining and find Autoglym Engine and Machine Cleaner does very well indeed (with the grey streaking that used to be my main problem, and any brown too). You seem perhaps to be implying ('Think I need a liquid to penetrate it') that the wallpaper paste prevents the oxalic acid from penetrating into the gel coat pin holes, so I think (depending on the area involved) I'd try pads of something absorbent soaked in an oxalic acid cleaner (taking due personal care of course) and taped onto the topsides for a while. Does that reasoning make any sense?

 

[cagey]

I use oxalic acid and wallpaper paste to good effect however still have some staining that wont budge, think its in the tiny gel coat holes, really bugs me having it there. Its an old hull, a hummingbird 30 based on an Elizabethan 30, so is a substantial build. Anybody got any ideas? Think I need a liquid to penetrate it. Tried polishing compound but that hasn't touched it . Cheers.

Try Harpic the thick one in black squeezy bottle, be careful of splashes on skin etc , has worked for me for years, I just put on with sponge leave for a few mins, wash off . A few areas need a couple of goes and a bit of effort but mosly it is almost effortless. I also do the entire topsides and the difference between treated and not treated is astonishing.
Best of luck