Yellow hull stain in holland?

[rich201283]

Hi
I have recently came back from holland and my yacht has now got a yellow stain where the waterline has been, I think its from the canals. Does anyone know the easiest way to get rid of this?

 

[Phoenix of Hamble]

Oxalic acid... available on-line from places like here

(its the common ingredient in most good quality fibreglass cleaners)

If you are having trouble getting it to stay on the fibreglass long enough, mix it with a little wallpaper paste...

It will remove the grime like you wouldn't believe, in fact so much so, that you'll end up wanting to do the rest of the hull!

 

[ccscott49]

Oxalic acid. Shifts it straight off.

 

[VicS]

As said oxalic acid. Make a near saturated solution but use warm water as it dissolve rather slowly in cold water. Add some wallpaper paste to make it thick enough to stay in place for a while.

Remember oxalic acid is very poisonous both by ingestion and skin absorption. So don't ingest it, and wear rubber gloves in addition to the normal safety glasses.

Alternatively buy Y10 from your chandler. It contains oxalic acid.

 

[Clyde_Wanderer]

Must say that Y10 is rubbish compared to pure oxalic acid, I tried both and the ox won hands down.
Y10 has less than 10% ox in it.
I bought it (ox) from a company called Wipe Clean in Clydebank Glasgow, 5kg for £19 odds.
Despite what AGW wood care say, it is highly poisenous and care must be taken when using it.
Oxalic is found in a lot of plants containing sorrel, ie, docken leaves etc.
Try to source it from an industrial cleaning suppliers, it will be much cheaper that way.

 

[Woodlouse]

As an added bonus the Oxalic acid will work to bring your teak decks back to their original colour as it just happenes to be the main ingredient in almost all teak cleaners aswell.

 

[jhughes]

Cuprinol garden furniture restorer - Oxalic acid and wallpaper paste in a tin!

 

[rich201283]

I have just bought some Cuprinol, Put it on and left it 15 min, Didnt seem to do much

 

[thalassa]

As I have my boat based in Holland, I'm very familiar with the problem. As many have said, oxalic acid, preferably in a slightly acidic solution. Add some white vinegar or better, very dilute hydrochloric acid.
The stain is a calcium deposit with iron oxides and algae mixed in. Next time you're in Holland, buy Radboud "Quick-Clean" at any chandlers. You take a rag, wet it with some water, spray a bit of the stuff on, wet the boat with the rag - rubber gloves on If above 15 degrees centigrade, most of the colour disappears without effort in fifteen minutes. Hose off after half an hour. I do this twice every season, takes me twenty minutes for a 30 footer.
In our club, we have tried it on an abandoned GRP sloop, that must have been white many moons ago. It had turned NUT BROWN, but was only slightly yellowish after the treatment.
IMHO, I would not go the abrasive route, as it makes the surface more porous, and will ascerbate the problem next time.

 

[Phoenix of Hamble]

Just for completeness..... none of the oxalic acid suggestions above are abrasive...

 

[castaway]

Y10 or oxalic as previously stated ....however it will remove any polish so be prepared to re apply... or you will find your GRP going brown again pdq.

Regds Nick