Marykate On and Off - Hull and Bottom 1 Gallon Cleaner, 128 oz

Very good for removing stains (rust as will) from fibreglass and cleaning hull. Be careful, contains acid

I don't review much, but was just on Amazon ordering some more for next year, and was surprised that this wasn't that "popular.". Maybe most people purchase from local marine store (like I did first time). Anywhooo.... To the point: 1)-- when I was a teenager, end of each boating season, we cleaned hull of family runabout with series of rubbing compound, polishing compound, then fresh wax job (yeah, I know, "novices" or your choice of -facetious adjective.... you won't hurt my feelings).... and Pop, if you're reading this, I forgive you, and I don't think this experience is a component of my current close relationship with the chiropractor. 2) later (and I won't admit how many years it took for us to "call-BS" on that approach), tried other products, then over time moved on to muriatic acid (WHICH THIS PRODUCT IS NOT--- but rather much more effective/efficient in my humble opinion). 3 Summary editorial: A This stuff is the berries-- one of those "are you kidding me?-type products." B) combo of hydrochloric, oxalic and phosphoric acids C) surprisingly used only 9/10th's of a 1 gallon bottle (yesterday) to clean entire hull of 25 foot Glastron GX255--**** that had been docked in fresh-water lake/reservoir for 5 months**** D) "FOLLOWING INSTRUCTIONS": i). definitely gloves, eye-protection, mask (first 2 years I used a bandana, this time a 3M particulate mask--b/c I had a box in garage--- but, probably no better than bandana, since won't filter gaseous fumes--you can get a mask that will work, I just opt to "try" to be careful..... avoiding the "enclosed spaces" is the key--this doesn't just mean doing it outside--rather if your crouching/kneeling/laying partially under boat on one side, particularly if there is no circulation/breeze or if you are "downwind," you're gonna get a whiff of some choke-worthy fumes (sometimes the more concentrated fumes are briefly visible). ii) method of application-- see "E" below E). Application: first year did it exactly as per instructions-- applied with paint brush, rinsed (I used an 1850psi cheapo-electric powersprayer). Worked beautifully, BUT, 7-8 hours in long pants, LS shirt, bandana on face and head, vinyl gloves filled with sweaty hands, goggles fogging-up nonstop-- and I still found a way to get a couple small blisters under watch band and back of neck. I also know I inhaled the most fumes that year. If you do it this way, I found that a mechanic's dolly is a godsend (the thing you lay on and roll around under stuff). --Second year--bought a telescoping-handled bristle brush. Better for your lungs and nasal passages, safer for your eyes and skin, but lots of wasted product, and somewhat challenging to apply without "honey, you missed a spot" (actually, I'm single, but most of you suckers are probably married, so figured I'd talk your lingo, no matter what your gender-- and if anyone researching this has 2 X-chromosomes..... WAY TO GO). --Third year--took it to detailing shop and had it done (think it was $200-300). --THIS YEAR: I'm sure many have thought of this before (I'm sometimes kinda slow)..... But my epiphany idea actually worked.... $6 garden/weed sprayer...... could adjust nozzle from mist to stream.... don't advise mist.... set it somewhere in the middle for the easy to reach places (kind of a "shower" spray for more uniform and complete application)...... adjust it more toward "stream" to get the harder-to-reach places. Now, could have been the cooler temp yesterday (45-50F), but we found that letting sit for 4-5 minutes helpful-- previous years, when warmer, this stuff literally "melts" the algae / waterline stains off as you stare in amazement, mouth agape, over 30-60 seconds, then spray it off. Caveats / Final thoughts: 1). Definitely needed good power sprayer yesterday (again, not sure, but suspect cooler temp?). 2). First 2 years did it in driveway, discolored focal areas where prolonged exposure--kinda looked "cleaner" concrete--but was NOT permanent. Apparently, it's technically eating-away at the pavement? 3). Put the pets inside 4). Yesterday, after spraying on acid, initially used that bristle brush to "spread around" because some of the product was obviously dripping off of the hull (and I didn't know how far the 1gallon was gonna go)---- I think this approach actually wasted more product, cuz had to hit these areas twice. Once stopped using the brush, letting sit for few extra minutes, were golden. 5). Product will "foam-up" a bit when it contacts the algae stains-- was helpful on dual-prop Merc outdrive, cuz lots of nooks and crannies, AND because once fairly clean, realized when rinsed and air-dried, would still have some residual patchy area of smegma stains. Sooooo, rather than waiting for complete drying after rinse, I just lightly sprayed again and areas that needed more would foam up. Will also foam up on any rust (we have a trolling plate mount with some screws that aren't the best)-- so seems to clean the little bit of rust off of these. 6). I use it on outdrive--takes a couple extra "spot cleanup" passes-- they sell an "outdrive-specific" product, I don't know if different or just marketing. 7). I use it on props-- takes several quick applications. 8 I havent covered trailer with plastic sheeting since first year..... I havent noticed any damage.... But, I'm sure it would with 5-10 minute exposure-- I did notice one silver dollar sized patch on diamond-plated side-step of trailer, where I'd ignorantly left a little puddle of acid probably 10 minutes--made it shiny probably took coating off. 9). I DID NOT LIKE THE "GEL" Formulation of this product-- tried initially year #2-- just absolutely did NOT work for me.... even with repeated applications of various "incubation times." 10). WHAT IF I GET THIS ON SKIN, IN EYES, ETC. -- obviously follow instructions, be smart and careful. -- but, only speaking in terms of my personal experience...... have gotten it on my skin numerous times (one nice thing is it's not insidious-- you'll know quickly, it starts to sting, and I've never had to do anything except quick 10-second water rinse) Got a face full of the mist a couple times yesterday (swirling wind)..... Coughed, closed eyes tightly, recoiled in Mild-moderate temporary discomfort...... splashed some water on my face and in my eyes..... nutted-up and moved on just make sure to remove your acid-splashed vinyl gloves first--- no, I actually thought to do this, surprisingly). And while i have donned eye protection 90% of the time while using product, I didn't have my goggles on when this happened, yep. 11). If I remember anything else to bore you with, I'll add it later 12). I'm not manic, and immodium AD does not help "verbal diarrhea"--but you see why I have to be selective with what I review 13) I certainly have no affiliation to MaryKate OR Ashleigh, although the former should reimburse me at minimum wage for the 2+ hours it took me to "2-finger type" this on this frigging iPad.

This hull cleaner is amazing. I use it twice a year and get the best results.

This stuff melts stains off of my boat like they never existed. It brought back the original white finish and now it’s hard to even look at my boat in direct sunlight. Be careful when using this. While it melts the stains away, it does emit vapors, and you need to use a respirator while applying this. This is by far the best product I have ever used to restore finish on the boat.

Does a great job. Just remember to wear safety glasses and a good charcoal cannister mask. Vapors are powerful

This product works great to remove the water tea stain. Wear gloves, eye protection and face respirator because it is very strong. Spray it on, rub lightly with a paint brush then rinse with water. Super easy.

It is highly toxic and corrosive to people, but it sure cleans a boat. Our boat is across from the gas dock and any spill goes all over my waterline. I couldn't get it off with anything, except MaryKate.

Worked like a charm so all of the water scum literally just rinsed off leaving a clean and shiny hull

Works like a charm.

Works really well, best boat hull cleaner out there hands down....spray on, wait a couple minutes then wash off. Use in a well ventilated area, strong odour.

Great product that works as intended, Work quick and make my boats hull look clean again

J’ai utilisé ce produit pour nettoyer la coque de mon bateau,le produit et bon mes sa ne justifie pas le prix payer trop chère.

The product works great. Just wipe on with brush, let it sit for a minute and rinse off. I have it an extra rinse with a cloth and it really worked. Stains were gone. If using on a boat, I would recommend waxing right after.