---
product_id: 5742677
title: "Marykate On and Off - Hull and Bottom 1 Gallon Cleaner, 128 oz"
brand: "marykate"
price: "A$210"
currency: AUD
in_stock: true
reviews_count: 8
category: "Mary Kate"
url: https://www.desertcart.com.au/products/5742677-marykate-on-and-off-hull-and-bottom-1-gallon-cleaner
store_origin: AU
region: Australia
---

# Fast-acting, visible algae removal in 30-60s Triple-acid formula (HCl, oxalic, phosphoric) 128 oz powerful hull cleaner Marykate On and Off - Hull and Bottom 1 Gallon Cleaner, 128 oz

**Brand:** marykate
**Price:** A$210
**Availability:** ✅ In Stock

## Summary

> 🛥️ Clean smarter, not harder — your boat’s glow-up starts here!

## Quick Answers

- **What is this?** Marykate On and Off - Hull and Bottom 1 Gallon Cleaner, 128 oz by marykate
- **How much does it cost?** A$210 with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.com.au](https://www.desertcart.com.au/products/5742677-marykate-on-and-off-hull-and-bottom-1-gallon-cleaner)

## Best For

- marykate enthusiasts

## Why This Product

- Trusted marykate brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Pro-Grade Acid Blend:** Harnesses a potent mix of hydrochloric, oxalic, and phosphoric acids for superior cleaning power without harsh muriatic acid risks.
- • **Safety-First Formula:** Use with gloves, eye protection, and proper ventilation to keep your DIY boat care safe and effective.
- • **Effortless Deep Clean:** Melts away algae and waterline stains with a single application, saving you hours of scrubbing.
- • **Versatile Application:** Perfect for hulls, outdrives, and props—tackles rust and grime in hard-to-reach nooks with ease.
- • **Economical & Efficient:** One gallon covers a 25-foot boat hull with room to spare, maximizing value for seasonal maintenance.

## Overview

MaryKate On and Off Hull and Bottom Cleaner is a 128 oz professional-grade solution combining hydrochloric, oxalic, and phosphoric acids to rapidly dissolve algae, rust, and waterline stains on boats. Designed for DIY enthusiasts and pros alike, it delivers fast, thorough cleaning with economical coverage, making seasonal boat maintenance safer and more efficient.

## Description

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

Review: *** DIY Boat Owners : CONSIDER TRYING THIS STUFF *** - I don't review much, but was just on desertcart 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.
Review: AMAZING PRODUCT - This hull cleaner is amazing. I use it twice a year and get the best results.

## Features

- Sport Type: Boating

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B0000AXNNI |
| Best Sellers Rank | #71,564 in Sports & Outdoors ( See Top 100 in Sports & Outdoors ) #87 in Boat Cleaners |
| Brand Name | MaryKate |
| Color | White Emulsion |
| Customer Reviews | 4.7 4.7 out of 5 stars (267) |
| Date First Available | October 1, 2001 |
| Fishing Technique | ….. |
| Hand Orientation | Each |
| Included Components | MaryKate On and Off - Hull and Bottom 1 Gallon Cleaner, 128 oz |
| Item Dimensions LxWxH | 13 x 13 x 13 inches |
| Item Package Dimensions L x W x H | 12 x 9 x 9 inches |
| Item Weight | 2.4 Pounds |
| Manufacturer | CRC INDUSTRIES, INC. |
| Material | Plastic |
| Model Name | MK20128 |
| Number of Items | 1 |
| Package Weight | 9.3 Pounds |
| Part Number | MK20128 |
| Size | 128 oz |
| Sport Type | Boating |
| Suggested Users | unisex-adult |
| Warranty Description | Warranty |

## Images

![Marykate On and Off - Hull and Bottom 1 Gallon Cleaner, 128 oz - Image 1](https://m.media-amazon.com/images/I/71hM-Zr8KcL.jpg)

## Questions & Answers

**Q: Will this product harm bronze hardware?**
A: It's really great stuff to clean my boat hull. I never used it on anything else.

**Q: can on off be sprayed from a pump tank ?**
A: Not sure what you mean by "pump tank". It can be used in a pump sprayer, works quite well.

**Q: Is this environmently friendly**
A: It’s not a prohibited substance, but it is a very strong acid, so it’s pretty much guaranteed to kill whatever you pour it on, similar to toilet bowl cleaner.

**Q: Can you use this in a pressure washer?**
A: Don’t recommend it.

## Customer Reviews

### ⭐⭐⭐⭐⭐ *** DIY Boat Owners : CONSIDER TRYING THIS STUFF ***
*by B***A on November 5, 2011*

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.

### ⭐⭐⭐⭐⭐ AMAZING PRODUCT
*by C***S on June 10, 2025*

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

### ⭐⭐⭐⭐⭐ Amazing!
*by W***S on February 8, 2025*

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

## Frequently Bought Together

- MaryKate On and Off - Hull and Bottom 1 Gallon Cleaner, 128 oz
- STAR BRITE Non-Skid Deck Cleaner & Protectant Ultimate Boat Deck Wash - Protects Against Future Stains & UV - Ideal for Fiberglass, Vinyl, Plastic, Painted & Metal Surfaces
- Meguiar's M4364 Marine/RV Boat Wash - 64 Oz Container

---

## Why Shop on Desertcart?

- 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016
- 🌍 **Shop Globally** — Access 737+ million products across 21 categories
- 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price
- 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members)
- 🔒 **Secure Payments** — Trusted payment options with buyer protection
- ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews

**Shop now:** [https://www.desertcart.com.au/products/5742677-marykate-on-and-off-hull-and-bottom-1-gallon-cleaner](https://www.desertcart.com.au/products/5742677-marykate-on-and-off-hull-and-bottom-1-gallon-cleaner)

---

*Product available on Desertcart Australia*
*Store origin: AU*
*Last updated: 2026-02-20*