PS Advisor September 2017 Issue

Getting Rid of Impossible Bird Poop Stains

I honestly hope you can help. Several weeks ago local seagulls had a sushi feast on my boat. The leftovers were large and small and mostly on non-skid. When I got to the boat I cleaned up whatever I could pick up, but the sun-baked stains remained. I’ve tried whatever I possibly could including Barkeeper’s Friend and Total Boat White Knight. They both have oxalic acid as main ingredient. It stayed there for 30-40 minutes, I didn’t touch it. Next I got oxalic acid as powder and made my own very strong mix. Again, no major effect. Next, In desperation, I broke out 3000 PSI power washer, which again didn’t remove the stains. My marine biologist friend said to try Draino.

Val Vechnyak

via email

portable compressed air kit
Applying grease to the folding prop is made easier with a portable compressed air kit.

We’ve not tried Draino, but can recommend a method that has worked very well for us. With any stain, you want to start with the least aggressive cleaner. An ordinary boat soap or phosphate free laundry detergent (diluted as directed) will get most stains if your hull is recently waxed. If that won’t work, your next weapon is diluted chlorine bleach.

If bleach fails, move on to acids. We suggest a cleaner containing hydrochloric acid (HCl). You can make your own solution using diluted muriatic acid (30-35 percent HCl) from a pool supply house or hardware store. This will be the least expensive route (see “One Bucket Cleaning Kit,” PS May 2017.) Dilute with water to get a 3 percent solution of HCl. Pour acid into water—never the opposite—and protect your eyes. You can try a slightly higher concentration, but be careful! The pH is very low and this concoction will quickly corrode aluminum and most other metals.

Your other option is to use an over-the-counter cleaner (marine or otherwise) that is pre-diluted with hydrochloric acid. You have plenty to choose from. One of our top rust-stain cleaners (see “Rust Erasers,” PS May 2006 online) or waterline stain cleaners would be a good choice (see “PS Tests 22 Hull Cleaners,” PS November 2007 online). Spray-type cleaners finished top in both tests, but for a vertical surface, the gels can be more effective. Whatever acid you use, don’t let it dry, and rinse well with fresh water.

If acids can’t remove the stain, we move on to a rubbing/buffing compound, which removes oxidized layers of gel coat that hold the stain. If you have a light-duty rubbing compound or a cleaner-wax, try that. You’ll likely need a heavy duty compound, and we’ve tested several (See “Heavy Duty Rubbing Compounds,” PS April 2014.) Unless the entire deck could use a buffing—and it sounds like it might—you can apply these to the stain by hand.

This should take care of the stain, but your work is not done, yet. In order to save you trouble the next time, you’ll want a layer of wax to protect the surface. The simplest, safest protection for decks is a wash-n-wax. You can opt for a special non-skid wax (see “Non-skid Waxes,” PS October 2006 online), but the wash-n-wax cleaners produce a surface gloss that makes it easy to hose off bird poop, yet is not too slippery. There’s a barge-load of boat soaps that will work (see “Boat Soaps for Regular Washdowns,” PS January 2013 online). As an added measure, you could apply a spray wax (see “Searching for Spray Waxes,” PS December 2014). Most are not too slick for a deck, but to be safe we’d test first, or reserve these for spots where you don’t need traction.

Finally, you should look at bird deterrents. Physical barriers worked best in our test, although some species have an aversion to owls and kites and things that flash. See “Do-it-Yourself Bird Deterrents,” Inside Practical Sailor blog.

If you’re really serious about cleaning check out our four-volume ebook series: “Marine Cleaners, the Complete Series,” which covers more than you need to know to keep your boat looking her very best. It’s available at our online bookstore

Comments (10)

This comment is about prevention, not cure. Several years ago I was brushing Starbrite liquid waterproofing on my canvas dodger, and accidentally knocked over the bowl with the Starbrite and it went all over the deck. The instructions say not to apply this product to fiberglass, but my non-skid deck is the texture of course sandpaper and the stuff soaked in at once before I could clean it up. To my surprise, it didn't stain my light grey deck and thereafter, water beaded up on the deck where the spill had occurred. The next year, I painted all non-skid areas with the stuff and it created a waterproof coating that lasts for years. I contacted Starbrite to ask why the label says not to apply the product to fiberglass, and told them of my results. They said the warning was only there because, depending on the color of the deck, it COULD stain, but the product is clear and will seal the pores in just about material. The only downside is that the deck is slippery for a couple of weeks, so I apply the stuff very early in the season and only once every few years. Water will bead up on the deck for at least several seasons.

Mark, Rigoler

Posted by: Rigoler | September 4, 2017 9:51 AM    Report this comment

Try Woody Wax on everything from metal to fiberglass as a protectant wax, especially in this case, on non-skid. Spray on, move it around, let it dry, and buff off. Not inexpensive but worth the price. This is of course is not a cleaner, but a protectant.

Posted by: osead | September 3, 2017 11:24 AM    Report this comment

Starbrite make a product called Bird & Spider Stain Remover that works like a champ on about anything.

Posted by: cemead | September 3, 2017 8:48 AM    Report this comment

tr, just so you know, vinegar IS an acid. Acetic acid.

Posted by: agingbull | August 28, 2017 4:27 PM    Report this comment

The most effective solution to the bird droppings problem that I have found is to make a solution of 40% white vinegar and 60% fresh water. Soak rags in the solution and lay over the poop. Keep soaking the rags for a half hour. Wipe up droppings.
Acids don't work. A base, vinegar does. Works on fglass, canvas and teak

Posted by: tr | August 28, 2017 6:30 AM    Report this comment

The most effective solution to the bird droppings problem that I have found is to make a solution of 40% white vinegar and 60% fresh water. Soak rags in the solution and lay over the poop. Keep soaking the rags for a half hour. Wipe up droppings.
Acids don't work. A base, vinegar does. Works on fglass, canvas and teak

Posted by: tr | August 28, 2017 6:30 AM    Report this comment

Cleaning fiberglass. I just encountered this on a small sailboat covered with mouse poop and pee. Boat has been sitting for years. Here's what we did:
1. Scrubbed with detergent- no impact
2. Power washed. 3,000 psi No impact
3. Scrubbed with Comet containing bleach. No impact.
4. Mixed up my deck cleaning solution of Sodium Percarbonate in a 5 gal pail of water. Brushed it on. Well you're supposed to use hot water, I took my Paul to add hot water. I returned to the boat in 5 minutes. WOW. It was clean and looked brand spanking new. No scrubbing. Just rinsed. Magic. 😃

I used 3 coffee scoops in the pail.

5. Sodium Percabonate is the active ingredient in Oxiclean. It releases hydrogen peroxide when mixed with a water. I buy it on Amazon. It's 99% active ingredient and cheap. The stuff in the store is around 50% Sodium Percarbonate I'm told.

Posted by: Seawind | August 27, 2017 4:19 PM    Report this comment

I have had good luck with a mixture 50/50 or less liquid dish detergent and chlorox bleach. It was the only thing that removed white fly stains here in florida. I tried every else but only this worked. Put it on with a medium brush, let it sit a few minutes and brush it off. It will take some pressure on the brush to do it. My gelcoat was old so it did no harm. Of course wash immediately to remove the bleach.

Posted by: | August 27, 2017 2:19 PM    Report this comment

Poop Off is sold on pet supply stores and used to clean bird cages. Works wonderfully.

Posted by: Ebennettr | August 27, 2017 11:01 AM    Report this comment

I have used easy off oven cleaner on dried Comorant poop. Nothing else worked. It worked great.

Posted by: ecamiel | August 27, 2017 8:56 AM    Report this comment

New to Practical Sailor?
Register for Free!

Already Registered?
Log In