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Old 31-12-2011, 02:43   #1
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My boat is supposed to be white, but because of the amount of time on the river, has yellowed. Any idea on how to return it to its original color?

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Old 31-12-2011, 03:13   #2
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pirate Re: Yellow

When I was fixing up a Hunter I was taking to the UK.. Sailcraft in Oriental, NC .. great yard by the way... I watched a couple do their hull, they used a 50/50 mix of water and something called OnOff I think it was... used to eat of all the non plastic crap... bit like bleach in the loo.. worked okay on the Hunter to..

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Old 31-12-2011, 04:24   #3
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Re: Yellow

On/Off is a mix hydrochloric and phosphoric acids and works great at removing stains - just be careful not to get it on you or any aluminum parts. Another good choice for removing yellow stains is oxalic acid. Buy it at the hardware store (might be called wood bleach there) in powder form and mix with water. Spray on, let sit a couple of minutes until white and rinse off. This is also great for removing rust stains.


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Old 31-12-2011, 04:37   #4
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Re: Yellow

If using Oxalic acid on the hull, it can be useful to put some wall paper paste into the mix, keeps the solution hanging on to the vertical surface, but make sure you rinse off well.
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Old 31-12-2011, 11:11   #5
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Re: Yellow

I haven't tried this, but found it on another forum.
Maybe it would work.
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Old 31-12-2011, 12:07   #6
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@Nigel1: it is, in fact, the hull that has yellowed. The top one-third of the boat is still white. Will this stuff bleach the carpet?
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Old 31-12-2011, 12:15   #7
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Re: Yellow

Oxalic is cheap and works well but I use a gel product to try and keep the acid off the anti-fouling bottom paint. Acids will eat the copper right out of the bottom paint if not used carefully. This could potentially make the one or two inches above the waterline basically useless at repelling growth if you cleaned your boat in-water then loaded it for cruising. If you do it out of the water without a drip skirt you could ruin a lot more of the paint.

The hull of my boat is always waxed and I really don't get to much if any tannin or mineral staining. A good coat of wax can go a long way to minimizing these brown stains. I did however leave my inflatable in the water for a few weeks and got enough staining to illustrate the process.

This is easy and is safe for gelcoated hulls. While I have used acids on LPU paints I don't suggest it unless you are really, really, really careful.

To clean waterline stains I use MaryKate On & Off Gel. This is a HUGE improvement over the regular non-gel On & Off or basic Oxalic. It's also a lot cheaper and stronger than Davis FSR stain remover but works similarly. There are a lot of products out there that contain acid and will work but the On & Off Gel is one of my favorites. It also has much less "acid" odor than the regular On & Off. This is a great step to do before waxing a boat and it will whiten up most any old tannin/rust stained gelcoated hull.

Wear rubber gloves, this stuff is acid, and use cheap chip brushes to apply. This whole process on my inflatable takes less than 10 minutes and requires NO rubbing. Simply apply with the chip brush and watch it eat away the stains. Regular oxaic acid, or oxalic acid crystals mixed with warm/hot water will work too, and is slightly cheaper, but it is thinner and can drip and run and can eat the copper out of bottom paint. The gel stays put for the most part with considerably less dripping. This bottle lasts me about four to five years...


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Old 31-12-2011, 13:17   #8
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@Marine Sail: if you are male, then all I can say is "YOU ARE THE MAN!!!". Thanks so much! I appreciate the pictures too. Seemed to work beautifully!
One last question; do you simply rinse this stuff off after application? Will it kill my grass when I wash it off?

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