How To Remove Rust/Tannin Stains From Your Hull

[Maine Sail]

Hi All,

I've been meaning to take some photos of this procedure for a while but the hull of my boat is always waxed and I really don't get to much if any staining. 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. It's also a LOT cheaper and stronger than Davis FSR stain remover but works similarly. 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 hull.

Always wear rubber gloves, this stuff is acid, and use cheap chip brushes to apply. This whole process on my inflatable took less than 10 minutes and requires NO rubbing. Simply apply with the chip brush and watch it eat away the stains..

Before:

The Products:

During:

All Finished:

 

[Art L]

Good job on demo and pictures. Thanks Art L

 

[sailormanbigd]

Rust/tannin

hi, nice post. Thanks. I have had good luck with "The Works" bathroom cleaner. The toilet bowl cleaner works the best but has a very strong acid smell. I think the shower cleaner that says it is for rust, calcium, lime stains probably would do the same as well. I get it at walmart for $1.18 for a large bottle, but others have told me to get it at Dollar store. No amount of wax on my hull prevents the staining. I actually waxed one side and not the other to compare, no decernible difference. Patrick

 

[Maine Sail]

No amount of wax on my hull prevents the staining. I actually waxed one side and not the other to compare, no decernible difference. Patrick

Patrick,

What do you use for a wax or sealer? The best waxes will only last about six months max, and that's pushing the envelope, even if applied correctly.

I had very good luck with Colinite Fleet Wax #885 on gelcoat and currently use AwlCare on my Alwgrip finish. I had zero rust at the water line this season but my un-waxed dinghy well........

She came out of the water on Friday afternoon Oct 11 and I took this photo Saturday morning Oct 12. This is untouched other than the boat yard pressure washing the bottom. I do plan to wax her before winter but as you can see the AwlCare, applied last April, did a great job of preventing rust stains at the waterline..

 

[dbecker68]

I have a similar stain on both sides of the bow of my Hunter 30 "DreamBoat". We "cleaned" the hull with Zud at last haul out (June 2008) and waxed the entire hull. Within weeks the stain was back. I cannot wait to try your process. That's a beautiful photo, by the way. DreamBoat is 26 years old, and we have had her for almost 5 years. She's a good old boat, but doesn't look anywhere near that good.

 

[davejb851]

Just a quick wonder, and while I understand all these chemicals need to be strong in order to work, does this stuff do anything to the water, fish and eco-system they get rinsed into? I would love to clean the bottom of my sailboat with something degradable, or at best, whatever has the least impact on all those things listed.

Just as some background, I am a member of an organization here in New Bedford, "The Coalition for Buzzards Bay" that is working towards reducing nitrogen loading, and trying to reduce other man made products from getting into the marine environment. We are seeing algae blooms, fish kills, and degradation of aquatic plant life where there is little concern for the impact, and just the opposite result from places that monitor and attempt to educate about the cause and results.
A simple question with two cents offered from a sailor, and an ihabitant of the seashore.

 

[Ctskip]

Maine Sail,
Have I told you lately that I hate you? I'm just glad you and your boat are up there. and I'm down here.
Keep it up,
Ctskip

PS: the boat look grrrrrrreat

 

[Phil Herring]

Yeah, that is gorgeous boat, isn't it?

 

[ITMaster]

That Boat Looks

Better coming out Maine Sail than mine does going in. How in the world did you do that to it? That is a gel coat with the color in the gel, isn't it?

Regardless, she looks brand new, if you aren't proud of it, you should be. I don't know if I have ever seen a boat with a finish that pretty .


Tom

 

[Maine Sail]

She's not gelcoat..

Better coming out Maine Sail than mine does going in. How in the world did you do that to it? That is a gel coat with the color in the gel, isn't it?
Tom

I wish she was gelcoat but she's not! It's Awlcraft 2000 which is a two part acrylic paint similar to Imron..

 

[CalebD]

Dave,
According to Defender.com this product (On & Off) is 'biodegradable' but according to WM (and Defender) it is a shipping hazard and can only be shipped over ground. It is a highly acidic solution or gel that contains either sulfuric acid, oxalyic acid among other main ingredients (not something anything living will enjoy eating much). Once the acids are diluted (watered down) and react with anything that will reduce their acidity they may in fact be somewhat 'inert' leaving fairly natural byproducts. I would not call this an eco-friendly product like Vinegar (or acetic acid which is much less acidic and has a higher and more neutral pH value).
The best way to neutralise strong acids is with a 'salt' like sodium bi-carbonate or sodium chloride but there are still resultant particulates that contain sodium (Na - and Cl, or chlorine which together make up NaCl, or salt, which is one of the main components of sea water.
There are few good 'green' choices for this task that do not require a LOT more elbow grease than the more toxic stuff. The worst thing about this product is some of the chlorine gas that you can smell and feel in your nose as it evaporates from the mixture.
I am not sure if I have helped you but if you use as small amount of this product as you can then you will minimize your footprint and you can scatter some 'salt' into the leavings to help neutralize the acidity which will kill a lot of marine life. If my memory of college chemistry serves me, sea water is just a bit basic (eg., 7+ pH) rather than acidic (pH < 7). The stronger the acid, the lower the pH.
Trying to sand off the discoloration of marine growth that Mainesail is talking about will result in other problems like creating small particulates of gelcoat (plastic or vinyl) that float about (forever) in the ocean.
The best way to leave the smallest footprint is to use the smallest amount of strong chemicals to do the job, IMHO.
Good luck.

 

[Maine Sail]

It took..

It only took about 2-3 oz of this stuff to do the entire dinghy as a little goes a long way.

Personally I'd be more concerned about the copper bottom paint or the dish soap used in the galley sink. Another more noteworthy concern on the "acid" front would be the hundreds to thousands of gallons of Liquid Draino used to unclog drains that then flows into municipal water systems and eventually dumps into our bays during rain storm overflows than a very tiny bit of acid once a year.

Our municipal water supplies and systems are generally the biggest offenders when it comes to polluting our bays not boaters..

 

[afteryou]

I had never experienced hull staining until we took a couple trips from Lake Michigan to the Bahamas and back. The stains appeared while transiting the Erie Canal and worsened as we travelled down the ICW. While in Ace Hardware in Brunswick, GA, I discovered a product called Rust Aid. It is for removing rust stains from stucco, siding, sidewalks caused by irrigation sprinklers. It comes in gallon jugs for under $10, and the principal ingredient is Oxalic Acid which is not as hazardous as other acid cleaners like On-Off. One gallon will do 2 or 3 boats easily. Just put the Rust Aid into a garden sprayer (full strength), wet the area to be cleaned with water, then immediately spritz the surface with the Rust Aid. Let stand for about 2-minutes and the stain will vanish. Then rinse-off with water. Stubborn spots may need a second application or light wiping with a sponge. This can be done with the boat in or out of the water. It will not strip wax. I had two coats of Meguiar's Flagship wax on the hull and after stain removal, the shine remained for most of a year. Other products such as fence and deck cleaners will also work if the principal ingredient is oxalic acid. I have amazed many with this simple procedure!

Brian Nelson
S/V Afteryou

 

[sailormanbigd]

wax

Maine sail, i first washed the boat with dishsoap in the driveway, then buffed it with 3m microfinishing compound, then i used a new synthetic wax for cars. It shined real good and wasn't too porous visually that is. The boat sat at my buddies house for a 1-1/2 weeks in a saltwater river. The staines were identical on both sides. The bathtub ring did'nt come off with the "Works" it was more oily thn tannin. Beautiful boat by the way! Patrick

 

[Maine Sail]

Oil type stains

The bathtub ring did'nt come off with the "Works" it was more oily thn tannin. Beautiful boat by the way! Patrick

Yeah oil type stains still stick to wax and removing them will require new wax. Even wax won't prevent tannin staining completely depending upon where you are. I've seen the Chess put a mustache on a freshly waxed hull in less than four weeks..

If you're in an area of mild tannins and suspended metals then a wax will greatly minimize it but not entirely prevent it. My boat above was in the water from early May to October 11th and my un-waxed dinghy spent about four weeks total in the water so it's a good illustration of what wax can do in a mild to moderate environment..

 

[bffatcat]

stain removers

Call it rust, tannin, lime whatever. The active ingredient that cleans up the stains is oxalic acid. There are a dozen different products available for this job
The Marine products are more expensive than the general cleaners. Ive been
using a product called bartenders helper its in a powder form and comes in a can similar to ajax or comet. you can get it in most supermarkets for about $1
a can. Takes a little scrubbing with a brush but cleans the stains up. For those interested I do this job after the boat is hauled and wash down the area
thoroughly when Im finished. It takes 3 0r 4 oz of this powder to clean up my 26 footer

 

[Maine Sail]

Call it rust, tannin, lime whatever. The active ingredient that cleans up the stains is oxalic acid.

While hardware store Oxalic acid will work for this it is not the ingredient used by CRC/MaryKate industries in On & Off. The active ingredients are Hydrocloric and Phosphoric acids.

Oxalic will work fine but the gel feature in either Davis FSR, Y-10 or MaryKate On & Off make it very worth it especially if you have and use a multi-season ablative paint.. You do not want any acids running and or dripping onto a multi season ablative or it will kill it. The gels like FSR, Y-10 or MK On & Off Gel stay in place quite well. This bottle of MK On & Off gell will probably last me about five years...

Also be very, very careful "spraying" any acids!!!! Airborne acids landing on aluminum will pit and eat away any anodization quite easily..

I like the gel because it pretty much stay where you put it...

 

[48dodge]

Call it rust, tannin, lime whatever. The active ingredient that cleans up the stains is oxalic acid. There are a dozen different products available for this job
The Marine products are more expensive than the general cleaners. Ive been
using a product called bartenders helper its in a powder form and comes in a can similar to ajax or comet. you can get it in most supermarkets for about $1
a can. Takes a little scrubbing with a brush but cleans the stains up. For those interested I do this job after the boat is hauled and wash down the area
thoroughly when Im finished. It takes 3 0r 4 oz of this powder to clean up my 26 footer

In case anyone is looking for the product bffatcat mentioned, the name is Barkeeper's Friend. I have used it on rust stains on a smaller scale than what MaineSail has to deal with. It does a great job. I don't know if it's as fast or as easy as OnOff, but I think it would probably give it a good run for its money.

 

[Maine Sail]

Please be careful

In case anyone is looking for the product bffatcat mentioned, the name is Barkeeper's Friend. I have used it on rust stains on a smaller scale than what MaineSail has to deal with. It does a great job. I don't know if it's as fast or as easy as OnOff, but I think it would probably give it a good run for its money.

Please be careful using Barkeepers Friend. While it does contain Oxalic acid it also contains mild grit abrasives. These abrasives can leave micro scratches in the surface of gelcoat or paint which will then give more surface area for stains to attach to. While probably not as abrasive as Commet or Ajax it is abrasive and after use the area should then be buffed or polished to remove these micro abrasions to the gelcoats surface. A glass smooth glecoat leaves less surface area for stains or UV rays to begin attacking..

A straight Oxalic acid, or any of the Gel based acid cleaners, contain no abrasives as they are not needed to remove rust or tannin staining..

 

[48dodge]

Re: Please be careful

I've always made a paste out of it when using it on gelcoat (boats, fiberglass tub)