Cleaning the yellow stain

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Sep 25, 2008
11
Clipper Marine 21 Des Moines, Ia.
What product works the best to remove the yellow stain on the hull left from repeated splashes of lake water?
 
Sep 25, 2008
7,695
Alden 50 Sarasota, Florida
Not sure any one specific cleaner is best but among the many that are effective is FSR for this type tannic acid staining
 
Jun 2, 2004
5,802
Hunter 37-cutter, '79 41 23' 30"N 82 33' 20"W--------Huron, OH
Behr Deck Cleaner is my favorite. Easily found in the big box stores. I can apply it from the dock or the deck with a long-handled brush from a bucket. Let it set the prescribed time. Then rinse repeatedly with the hose. No rubbing required.
 
Jan 1, 2008
89
Islander 36 Salem MA
On Off works very well BUT I won't use it because of it's hazzards . I would think that a real good wax job in the spring may help to slow the yellowing down .
 
Sep 15, 2009
6,244
S2 9.2a Fairhope Al
not sure about on fiberglass but lemmon juice works well on maple staine on my hands after working with raw maple in the shop ...maple leaves a blackish color on my hands and the easyest way to remove it is to take real lemmon juces and rinse my hands with it ....presto stain is gone

regards
woody
 
Dec 9, 2005
164
Kirie Elite 37 Pascagoula, Mississippi
Look in Walmart's sporting goods section and you'll find hull cleaner....it works great. Be sure to apply wax after rinsing with fresh water or it will stain again in no time. I do this once a year and have found it to work great.
 
Feb 6, 1998
11,760
Canadian Sailcraft 36T Casco Bay, ME
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. Regular oxaic acid, or oxalic acid crystals mixed with water will work too, and is slightly cheaper, but it tends to drip and run and can eat the copper out of bottom paint. The gel stays put for the most part with considerably less dripping.

Before:

The Products:

During:

All Finished:
 
Dec 1, 1999
2,391
Hunter 28.5 Chesapeake Bay
I agree with Maine about the Mary Kate "On and Off" gel. I used to use the liquid, but the gel is a much better product for getting off the brown stains around the waterline. I, too, use gloves, goggles and if I think about, my respirator. This is nasty, but effective stuff if used properly.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
I would also suggest MaryKate but you may want to try Oxalic Acid. It is one of the main ingredients in a lot of the commercial cleaners. It comes in a powered form and can be mixed with water to form a liquid. If you spray it, just be careful to protect your eyes and lungs (that goes for any of these other products to).
 
Feb 10, 2004
4,235
Hunter 40.5 Warwick, RI
I also vote for oxalic acid that can be found in many common cleaners like toilet bowl cleaner. However there is a product called "Slimy Grimy" that is a powder, is bio-degradable that works like the others mentioned here without any rubbing. It is dissolved in warm or hot water and does an amazing job. I suspect that it's prime ingredient is oxalic acid too. It is very concentrated so that three tablespoons measure will make a quart of cleaning solution - enough for my h40.5.

Many of the lake boaters in my neck of the woods use this product. It comes in a small pail that makes five gallons of cleaner, cost about $25 at my local lake marina.
 
Sep 29, 2008
162
Morgan Out Island 33 Pompano Beach
Toilet bowl cleaner...can pick it up a bottle at a "dollar store". Apply with a soft rag and rub until the stain is gone. It really is amazing. It doesnt seem to work for any other staining. A bottle will last a long time. Beware...if your hull is painted, test it 1st. Wear rubber gloves and rinse thoroughly. This is alot less expensive than the "marine" cleaners. Bob
 
Jun 8, 2004
853
Pearson 26W Marblehead
for mainsail

I know Most of these yellow stains are Lime. And oxalic acid removes them Ive used a powder called bartenders helper, mostly oxalic acid. works but needs a lot of scrubbing Ive also used FSR jell which works easier but is expensive, This Mary Kate on and off jell does it work better? and if so where can I get it
 

Joe

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Jun 1, 2004
8,323
Catalina 27 Mission Bay, San Diego
liquid toilet bowl cleaner - right on.

My experience with that type of stain... lake water = algae. Use any acid based cleaner. By far the cheapest way to go... buy a quart of generic, liquid toilet bowl cleaner at your local Smart & Final (restaurant supply) for a few bucks. 5 or 6 capfulls in a bucket of water will dilute it perfectly. Simply dip your long handled brush in the bucket and swish off the brown/yellow stuff..... rinse immediately. ... You're good.
 

zeehag

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Mar 26, 2009
3,198
1976 formosa 41 yankee clipper santa barbara. ca.(not there)
i use baby butt wipes--the huggies brand is best --did my kayak--is plastric--and lasted like bottom paint --for 2 weeks lol---i also use clorox for that slimey stuff on the waterline...but i like the baby butt wipes best..easy to use and cleans hands too..LOL--i donot like using harsh chemicals--i try to get away with using that which i already have ---works...vinegar---- cuts the salts that build up on and in boats.....
 
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Sep 15, 2009
6,244
S2 9.2a Fairhope Al
how would the vinegar work on cleaning out the water jacket on a small engine....it has cylinder liners that are the wet type (yanmar 2qm15 to be exact) i have every thing cleaned but the block and am concerned that useing muratic acid 10% with 90% water might damage the liner O-rings

regards
woody
 
Jun 8, 2004
48
hunter 27 Savannah
stained topsides

Used to use toilet bowl cleaner, but after a couple of months the
stain was back. Now I use PMP Luster (some type of acryclic) on the entire topsides and haven't seen any stains for the last three years.
 
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