hull cleaning (on/off)

boatman37

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Well pulled the boat last Tuesday and found stuff called on off by MaryKate. Bought a gallon and did a test spot today on the starboard front. Sprayed it on with a RoundUp 1 gallon pump spray bottle and let it sit for a minute or two then rinsed with cold water from my garden hose. Got about 75% of it off so got a small scrub brush that I use for doing tires and very lightly scrubbed (really just 1 swipe with the brush) and rinsed and it was pretty clean. Probably would have been perfect but my boat at one time had bottom paint and there are still remnants of it and you can see some marking where the paint meets the gelcoat. I would love to get the rest of the bottom paint off but short of sanding I'm not sure how to.

Anyway, thumbs up for this product. I only did about 6-8' back from the bow on the starboard side and spent about 45 minutes or so on that. Tomorrow I am going to try power washing it first before using the on off to try to get most of it off first. I used about 1/4 of the gallon bottle so may need more. Guy at the marina said I would probably use just over 1/2 the bottle on a 25 'boat??? The directions say to brush it on so probably less waste if I did it that way. Just have to try to figure out how to get the area covered by the bunks without taking it off the trailer? Probably won't happen.

Power washing the stuff off after applying may be a better way too rather than a simple garden hose?
 

QBhoy

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Heard it's good stuff and don't want to ruin your parade, but why not cut out the middle man and go straight to the dealer....so to speak. This stuff along with many more products like it usually has an ingredient called oxalic acid in it as a base product.
This is the real miracle worker.
You can get it neat online (often called brick cleaner too)
I, along with many others in the know (and boat sales types) mix this stuff at 1/10 to really hot water. That is 1 part oxalic acid and 9 parts hot water.
Then spray or brush onto hull (below a certain edge or line on the hull). Do one side, the rear and then the other. By the time that's done, brush the first side, then the rear, then the other...then simply hose it off...making sure you get every bit off.
If the boat is on a trailer, make sure you wet down the trailer first, so that the acid doesn't drip onto it and eventually corrode it.
It's amazing stuff.
 

Scott Danforth

Grumpy Vintage Moderator still playing with boats
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oxalic acid is $20 for 10# on ebay
 

QBhoy

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Not good for those wee cuts on the hands, you didn't know you had....after working on the engine though...haha !
 

Old Ironmaker

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Dec 28, 2015
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I have been experimenting with hull cleaners for the past 12 years. I don't want to think of the money I have spent on "Miracles in a bottle." cleaners. My aluminum boat sits in gungy creek water with a low flow all season. Unless I want to spend a week and spend copious dollars I take the 19'er out at least twice a season to stay on top of it. Last year I was told by a Marina owner to mix 1 part Lysol Toilet bowl cleaner to 1 part Hydrogen Peroxide. Wet hull apply with chemical sprayer and scrub immediately, then rinse. One of the Guru's here told me Lysol is dan acid and the HP is a basic and it does work. 45 minutes to do 6 to 8 feet is slow to me. The Lysol/Hydrogen Peroxide works and works well. As far as a power washer vs. a garden hose unless it is a commercial power washer that can take paint off if there is a chip one of those residential power washers at 1800 PSI does little to get the grunge and Zebra Mussels off my hull. Once the hull is clean a garden hose works fine. It's easier, more convenient and less $$$$ for me to back the boat into a car wash and give her a wash if I travel away from home base. I do that before leaving especially if I take the boat to lakes that have not yet had invasive species like Gobies and Zebra Mussels. Actually I think it is law here in Ontario. I might be wrong, I do know it's good practice.

A tip for getting to those detail areas a knuckle busting scrub brush won't. I bought a 3" round stiff bristle brush that has a screw on top that is supposed to hold a liquid cleaner. I popped the back off and inserted a nut, bolt and lock washers, I glued the metal together with Gorilla Glue. I masked off the transducers and anything I thought might be susceptible to the Lysol mix and put it on my cordless drill. Works great for hard to get to spots like the transducers, rear ladder and riveted keel etc.
 
Last edited:

boatman37

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I did read about oxalic acid but couldn't find it locally and since it is going into storage this Thursday I didn't have time to order online. Will probably go this route next year though. I paid $45 for the 1 gallon bottle so not too bad.

As for 45 minutes for a small section, this includes the time it took to get everything out and put everything away. Actual work time was probably 15 minutes and the boat is pretty bad this year. Not sure why. No zebra mussels this year either. The last 2 years it was covered with them. Bjut the algae and scum line were really bad. Maybe warmer water?
 

jimmbo

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May 24, 2004
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oxalic acid is $20 for 10# on ebay

Used to use that stuff to boil out radiators. Industrial Toilet Bowl cleaner or Muriatic Acid(Hydrochloric Acid-same stuff your stomach uses to digest food) will work too
Oxalic Acid is found in Rhubarb leaves, which is why they are not edible
 

boatman37

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hmmmm. i used to eat rhubarb alot when i was a kid, but only the stalk, not the leaves.

i saw muratic acid at HD but wasn't sure if it would do the job or was safe so went with the on/off to be safe
 

Old Ironmaker

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We use Muriatic Acid to clean concrete. I might be hesitant to put it on my boat. I know the toilet bowl cleaner won't get spots on my driveway clean. Muriatic Acid will. Be careful handling the stuff. Eye and skin protection is a must.
 

Scott Danforth

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muriatic acid is hard on things like your trailer, concrete, etc.

oxalic acid is mild enough I soak rusty engine parts in it. Oxalic acid is normally sold as wood bleach
 

crazy charlie

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Plain old toilet bowl cleaner is 2nd best to Marykate On-Off which is the best,Thats correct, plain old toilet bowl cleaner.I buy it at the dollar store.Tidy bowl,Sno bowl and there is another brand which i cant recall the name.I do 2 boats for $4 .Empty them into a garden sprayer and spray them on a dry hull.Some brown stains will take 2 applications but it works great and is cheap.Just like On-Off it is an acid so you will want to wear gloves and glasses in case it is breezy.Does not work as well on growth on the bottom and sides but on the brown stains at the water line it is GREAT and Cheap!!
 

boatman37

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i used toilet bowl cleaner last year and it worked pretty good but not near as good as the on/off. but i think i messed up. i bought the 9% and diluted it down so it wasn't sas strong. i think i read on here if you get the 9% to use it straight.
 

crazy charlie

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dont dilute toilet bowl cleaner.Look for the one with the highest % of acid in it.They do vary.
 
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