Hull discolouration ( brown staining )

[hamishb]

Has anyone found a miracle cure for the common brown discolouration of white GRP hulls ? I use 'Starbright' hull cleaner which is very effective and restores to brilliant white again, but I know it is mild oxalic acid and I suspect that it destroys any surface protection on the hull each time it is used. ( I don't think it does any irreversible damage to the GRP ? ) The brown staining hence returns within a few weeks of sailing. Is there a product and/or polishing method which protects against this unsightly discolouration ? Has anyone found the cure......... or is it a fact of life on ageing hulls ?

 

[ccscott49]

Its a fact of liofe I'm afraid and not just on ageing hulls. You can try wax polish after the oxalic, but it wont last long.

 

[maris]

I would think the discouloration comes from metal starting to rust. If this is the case surely replacing the old fittings must be the answer. Ok that might be expensive but so are a few bottles of polish every year.

 

[ccscott49]

It's not normally metal rusting on the waterline of a fibreglass boat, it's normally just the normal water staining, or "waterway smile" as it's called in the intracoastal in the USA.

 

[vyv_cox]

There was a posting on this about 6 weeks ago. Due to shortage of time immediately before launching I only polished one side of the hull. In the marina berth where the boat spends most of its time, it faces due south, so sunlight distribution is more or less even per side. The polished side is now dark yellow and the unpolished is faintly yellow. The "unpolished" was polished during last season, so no doubt some traces remain.

Any organic acid is suitable for removal of this discolouration. Most commonly used is oxalic acid, either from the pharmacist or as a component of Teak-Brite or several other products. However, citric and lactic acids should be equally effective. These two are the active components of the stuff used to remove the furring in kettles, whether plastic or metal. I doubt whether any of these acids will harm gelcoat. Y10 is a product specifically aimed at removing these stains and I believe the active ingredient here to be oxalic acid, although my findings are that it is not very effective if the temperature is below about 15 degrees C.

I have now resolved not to polish the hull again and we'll see what happens.

 

[iangrant]

I used Y10 - like Vuv - only on one side of the hull about 6 weeks ago - boat faces South as well!

The treated side is still white - the untreated side is still yellow/brown. I'm going to do the untreated side at some stage when the dingy is inflated and I get round to it.

Ian

 

[maris]

Ok got you now. Tought you were all talking about the brown marks I've seen below the rigging of older boats. I've not come across water staining. I suppose living in the Highlands we get so much rain it keeps the hull clean. Happy sailing folks, Im going to miss out, got to go to work for the next 4 weeks.

 

[pvb]

Protective polish...

My 12-year-old GRP boat has a white hull. I use Y10 to remove water staining, mainly because I find its gel formulation easy to use. Once the hull looks white again, I polish it with Meguiars #45 Boat/RV Polish, then go over the whole thing again with Meguiars #56 Boat/RV Pure Wax. The theory is that the #45 Polish "feeds" the gelcoat and creates a shine, whilst the #56 Wax protects the shine.

What I really like about these Meguiars products is that they're astoundly easy to use - there's very little hard work involved. I've just done my boat (35ft) this way, by hand, in a day, and it looks good. The finish also lasts quite well; I only polish the hull every 2 years (when it's out for its 2-yearly antifouling).

Meguiars products are available in the UK from better chandlers. I know Fox's in Ipswich stock them, because that's where I get them from. Incidentally, I started using Meguiars after asking what sort of polish the Fox's boatyard guys use to get such a lovely finish on the Oyster boats they prepare there.

 

[Guest]

A product called Crystal Glo Restorer/Sealant got a good write up in Sailing Today, I'm intending to give it a try when the boat comes out in a couple of months.

Contact sales@marine-consumables.co.uk

Regards,

Peter
http://www.mistressofmourne.com

 

[Gunfleet]

People are always saying that you can get oxalic acid from a pharmacist. I've yet to find one who will sell it to me in England. You can buy teak restorer with 10% oxalic acid in it, but that's about that. For those living in France or Belgium Plastibrill is a fantastic cleaner for hulls, and I believe that does contain some oxalic acid but other stuff too.

 

[ccscott49]

You need to go to an old style chemist, not boots and ask them to order it for you, you'll get it, never had any trouble in Dartmouth, just try the chemist on victoria road.

 

[ccscott49]

Offshore?

 

[Gunfleet]

Done all that. Maybe it's an Essex thing.

 

[Guest]

Rust stain remover

I regularly (unfortunately) use a rust remover I got from Shamrock chandlery, could be a Starbright product. It works exceptionally well but the stains reappear after a couple of weeks or so. These stains are running down from the deck more than waterline discolouration. As there doesn't seem to be much noticeable real rust around I'm now beginning to wonder if it is actually wood colouring slowly coming out of the teak decking due to my using "teak cleaner/brightener" some months ago?

Bernie

 

[ccscott49]

Re: Rust stain remover

Its a very good chance that it is teak bleeding, but it doesn't normally happen too much, are you sure your decks are teak and not iroko, because iroko bleeds badly. But of course it could be residue left over from the cleaner/brightener.

 

[ccscott49]

Industrial chemists round you anywhere? or try classic marine in Ipswich, they might know of a supplier.

 

[Guest]

Re: Rust stain remover

The wood could be iroko, I have to admit I don't know how to tell the difference, but the boat was built in Taiwan from I believe "managed teak forest wood"

If I believe that I will believe anything??!

Anyhow, I would be happier thinking my stains were wood rather than rust!

Thanks for your info
Bernie

 

[ccscott49]

Re: Rust stain remover

If it was built in Taiwan, I'd be pretty sure it was teak, but plantation teak and old growth teak are two very different timbers, b ut as you say, as long as it's not rust, just clean more often!

 

[Gunfleet]

Nope. No industrial chemists. I might tryclassic marine next time I'm in Woodbrdge. He knows everything, including the way through the Deben bar. A web search reveals an art supplier in Guernsey which flogs the stuff.

 

[vyv_cox]

Oxalic acid source

My tub of Teak Brite is at least 6 years old, bought at Dickie's of Bangor for about a fiver, and it is still almost half full. I wouldn't think the hassle of sourcing the 100% oxalic, keeping it in a safe place, diluting it as needed, etc. is worth the effort.