Yellow Hull Stains?

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Sailfree

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Boat is 10yr old and waterline is going yellowish.

Is it a change of colour in the Gel Coat and it requires bleaching back to white or is it a surface residue thats best compounded off.

Don't want to grind away the Gel coat if its a chemical colour change that requires a chemical to restore it. On the other hand I don't want to bleach a surface deposit if I can remove it by compound.
 
Sailfree said:
Boat is 10yr old and waterline is going yellowish.

Is it a change of colour in the Gel Coat and it requires bleaching back to white or is it a surface residue thats best compounded off.

Don't want to grind away the Gel coat if its a chemical colour change that requires a chemical to restore it. On the other hand I don't want to bleach a surface deposit if I can remove it by compound.
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Try some oxalic acid. Buy powder on ebay, mix with water, put some warm water in a jug or old bottle and add powder till no more will dissolve - some left in crystals in the bottom. Decant liquid and wipe onto hull with sponge and rubber gloves (or as I did yesterday, a long-handled paint roller). In current summer temperatures you should see white back almost instantly. Hose off, then if feeling fussy polish.

Works beautifully in summer, less so in cold temperatures. Also cleans rusty stains from gelcoat around stainless steel fittings.
 
The yellowing seems to come from contact with water. It's even quicker and more obvious when the boat's been in fresh water.

Your local chandlery will have a selection of "yellow removing" products. We bought a gel, though it can be bought as a powder that you mix up. Roll it on with a paint roller, leave for 15 mins, then rinse off. Good as new.
 
jwilson said:
Try some oxalic acid. Buy powder on ebay, mix with water, put some warm water in a jug or old bottle and add powder till no more will dissolve - some left in crystals in the bottom. Decant liquid and wipe onto hull with sponge and rubber gloves (or as I did yesterday, a long-handled paint roller). In current summer temperatures you should see white back almost instantly. Hose off, then if feeling fussy polish.

Works beautifully in summer, less so in cold temperatures. Also cleans rusty stains from gelcoat around stainless steel fittings.
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+1 spot on
 
A friend had a Jeanneau built around 2000 which had the same problem. It was a problem with the gelcoat which was never resolved properly by the dealer. He sold the boat in the end.
 
For a relatively small area, I'd buy the gel (Y10 or similar). A tub lasts a very long time and it's easier than messing about mixing up your own.
 
Cardo said:
The yellowing seems to come from contact with water. It's even quicker and more obvious when the boat's been in fresh water.

Your local chandlery will have a selection of "yellow removing" products. We bought a gel, though it can be bought as a powder that you mix up. Roll it on with a paint roller, leave for 15 mins, then rinse off. Good as new.
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Mate of mine used oven cleaner from aldi with good results, cost about £1.50.
 
Sailfree said:
thanks for advice - does anyone know whether its a surface change of colour or a surface stain deposit?
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I suspect its a limescale type of deposit which then becomes stained by organic matter in the water

Oxalic acid is one of the strongest weak acids and is effective because it readily removes the initial deposit.
 
Sailfree said:
thanks for advice - does anyone know whether its a surface change of colour or a surface stain deposit?
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It is usually a surface stain deposit.

My boat had it from water in the River Fal. I removed it with Brick Cleaner from B&Q. You do not need to buy expensive "nautical" products.

Also, what I consider to be a better boat hull cleaner is Bell "Wipe Out", from Tetrosyl Ltd - if you can still get it. It is a powder that you apply with a wet sponge, leave for a short while and then wash off - along with the stain.

Alternatively, there is BoatLife Fiberglass (sic) Powder cleaner, that is similar to Wipe Out. It is a combination of Oxalic Acid and Alcohol Ethoxylate. Although a boatie product, this is an excellent cleaner that will also remove rust stains.[FONT=Arial-Unicode-MS+0]. http://www.mailspeedmarine.com/boat-cleaner-polish/boatlife/fibreglass-powder225899.bhtml[/FONT]
 
Definitely one for some OA crystals added to some warm water, I use a wallpaper paste to make it jelly like plus a squirt of Fairy liquid to give it a bit of colour, paste on wait for a while then wash off. Fantastic stuff but then again, I like rhubarb and custard......
 
If you catch it early enough or have previously corrected and protected, then a wipe with a melamine sponge possibly even a normal sponge and just water should be ample.

Much better for any passing fish etc, can you imagine passing by underwater with your eyelids forced open and swimming through chemicals no matter how mild they seem to humans?



Don't want to start pointing fingers as I use chemicals all the time as part of the cleaning / correcting process, but the point is, once corrected and then protected, further efforts should be often enough to not warrant using any harsh chemicals, at least in an ideal world.


Something as silly as cutting a lemon in half and rubbing this along the waterline or vinegar just might work, it might not, but think of naturally reversing the problems rather than reaching for the most toxic substance.

Now I know that the lemon certainly won't work on a waterline that has severe scale build up, for this indeed you would need the likes of brick cleaners and acids, but hopefully this would be once out of the water.


I don't have the understanding of chemistry like VicS here, but my opinion is that the yellow on most waterlines is tannin within the water.

The actual contaminates from boat to boat are going to vary however, oils, a rusting ship wreck nearby, the principle of how it gets dirty and stained will be the same.

There are different ways the tannin and others hold on.


The first is due to the surface of the waterline being slightly porous, so the stain is absorbed into the gel coat / paint and hides / shelters away from normal washes of the waterline, the more oxidised or 'open' the surface is, the more easily absorbed it is.

The other is above surface contaminates (like scale) sticking to the surface first, then being the carrier and becoming absorbed itself. Once again the stain has something to hide behind during normal washing, as scale won't be removed by average washing cleaners and shampoos.

Most scale (water spots) are white and not usually seen on white boats until severe or stained with the help of tannin etc, unless you have the pleasure of owning a a dark hull then you can see it right away, that's why they are hard work if you want to show off the hulls good looks.


Ok so there are many factors at play here and my ability to explain things is poor at best so please bear with me, re-reading my own posts I always get myself lost, apologies :nonchalance:



The waterline goes through a process of being soaked then dried over and over again, once the water that clings to the surface dries it leaves behind scale or TDS (total dissolved solids).

It is the same when you rinse a car with a hose but don't dry the water off, you will be left with water spots all over, this is the scale, the bits in the water that have dried in the sun.
The more often this process happens, the more scale.
A kettle element becomes worse and worse over time and you can see how scale builds into a formidable structure.

To reverse this process or break down the scale gently (without scratching up of the surface) you will need a de-scaler. Most of the products mentioned by others on this thread are just that, de-scalers.


From Viakal to Oxalic acid they work at breaking down the scale.

What I am worried about is it becoming far too common to just want to be told what the most active ingredient is in a product and use this as a way of dealing with things. Be careful is all I can say.

If you are going to use Oxalic, try a cup of warm water with just a spoonful of oxalic in, it will reverse the staining easily. Follow this up with a normal shampoo to ensure any residue has been rinsed or washed away.

It doesn't have to be a 4.3364% mix at a certain time of day with the wind blowing from the west, just add a bit to some water.
Treat it like an acid, be careful of you and others. Eye and skin protection.

Of course we want to be out boating and not be constantly cleaning, but if we could get the surfaces to a condition that would at least perform and help us a little.

As well as the condition being smooth, shiny and non-porous, to have the surface 'non-stick' or 'hydrophobic' is one of the keys.


Imagine lowering a non-stick saucepan down to the water line so that 50/50 of the pan is submerged.
Now when the water laps up the centre of the pan it runs straight back down again, There will be no water spots as there is no water on the pan.


In a year or two imagine what the condition of the pan would be like, both above and below the surface.
 
Marine Reflections said:
If you catch it early enough or have previously corrected and protected, then a wipe with a melamine sponge possibly even a normal sponge and just water should be ample.

Much better for any passing fish etc, can you imagine passing by underwater with your eyelids forced open and swimming through chemicals no matter how mild they seem to humans?
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Just washing does not get off the staining.

A bit of oxalic acid in gazillions of gallons of seawater is really not a big pollutant. Oxalic acid is an organic and is present in moderately high concentrations in many foods, from spinach to potatoes to fruits. I know it's just cosmetic, but I like a boat to look good. Rubbing on raw spinach leaves would probably also clear the brown staining but might leave the white hull a bit green.
 
A pot of Y10 then protect it by using a decent polish - Farecla have some very good products now. If your boat is coming out of the water for the winter, I wouldn't bother much now but give it a good seeing to once out of the water.
 
Non of the above!

Chine shine is the product you are looking for. I bought some and it does what it says on the tin.

Watch the video.

I will add, it's so good that you cant do a small area, the whole hull will need doing. Just working on a small area will leave the rest of the hull looking grim!

The video is not speeded up in any way, its just works as seen.

http://www.deckhandmarine.co.uk/store/en/hull-cleaners/10-chine-shine.html
 
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jwilson said:
Just washing does not get off the staining.


A bit of oxalic acid in gazillions of gallons of seawater is really not a big pollutant. Oxalic acid is an organic and is present in moderately high concentrations in many foods, from spinach to potatoes to fruits. I know it's just cosmetic, but I like a boat to look good. Rubbing on raw spinach leaves would probably also clear the brown staining but might leave the white hull a bit green.
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You are quite right, just washing alone does not normally get off any of the staining, further in the post I do try to explain why. I'm afraid my thinking doesn't transfer well onto paper and my poor punctuation doesn't help either.


The staining will be locked away in a porous surface (so beneath or within the surface of the gel coat) or it will be absorbed by scale that has formed on the surface of the gel coat. It might not look this way to the naked eye but my microscope tells me otherwise.


Either one (porosity or scale absorbed stains) usually both, normal washing with normal (PH neutral) shampoos won't be effective, as these won't be breaking down the scale nor will they be bleaching or leaching out stains from within the gels microscopic fissures.
For this you will need Oxalic, vinegar, lemon juice, chine shine, elbow grease etc, etc and many others.

My point is that, oh dear, just what is my point? wish I was good with words and had a little brevity to go with it...

My point is that with a little surface meddling (cleaning and polishing in preparation) followed by a hydrophic application, the staining wouldn't be so much of a problem and yes it certainly could then be removed via simple washing with PH neutral cleaners as opposed to harsher chemicals, these will only remove the scale, bleach, whiten the stains and prepare the area to accept its next fill of staining. It will just go round and round, cleaning - staining - cleaning - staining.

The cycle need to be broken with conditioning and protection.


I like a boat to look good too in fact it's a bit of a disease and agreed there is no immediate threat of Erin Brokovich taking on the pollution case any time soon.

My concern is that people are using Oxalic acid and much harsher chemicals to do the basic jobs that decent practice and a stitch in time would have solved, even basic washing the boat down is being done with Oxalic rather than a simple shampoo.
And ok, forget my concern for wildlife, it will save you an awful lot of effort if you transfer the above philosophy to the rest of the boats surfaces, I promise.

Cliffdale, yes for actual prep work this does work very well, certainly worth a go if one has only used Oxalic or other acid cleaners. Pricey compared, but worth it.
 
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Cardo said:
The yellowing seems to come from contact with water. It's even quicker and more obvious when the boat's been in fresh water.

Your local chandlery will have a selection of "yellow removing" products. We bought a gel, though it can be bought as a powder that you mix up. Roll it on with a paint roller, leave for 15 mins, then rinse off. Good as new.
Click to expand...

Expensive mix of oxalic acid and wallpaper paste - make your own. The wallpaper paste prevents it just running off onto the antifoul.
One possible snag - the newly cleaned pristine waterline will make the rest of the gelcoat look yellow and shabby!! So brace yourself to do the whole hull.
 
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