Removing brown water stains

[fitzpatl]

Hi

I live on the Magothy off the Chesapeake and we're experiencing a "mahogany tide" (prorocentrum minimum--an algae). Due to low tides and lots of use, I left the boat in the water for 2 days (off the lift). Now the hull is tea-stained below the waterline. Neighbor told me it's the "Magothy mustache." Although in 8 years, first time I've had this happen.

It's only on the white part of the hull (which is gelcoat not paint, right?), but the area just above the staining is midnight blue imron.

I've read that the normal oxalic acid treatments (MaryKate's On&Off) are not good for the Imron -- so I'd take pains to make sure it stays clear. Moreover, I've heard that these cleaners degrade the gelcoat with each use. One article suggested that Interlux Heavy Duty Stain Remover (gel) is safe for painted surfaces.

What's the best way to get rid of the staining without harming the gelcoat & paint?

Cheers
Larry

 

[tpenfield]

Try "Iron Out" to see how it does. Start with a small area.

 

[Alec A]

At least you didn't have the red tide that we had here for about a month during the lockdown. Red algae that flooded the lagoons and killed fish. When you go outside, it would smell like a rotting sewer---as the red tide algae takes the Oxygen out of the water and kills the fish. Lots of dead fish. It's about over now---but people were even calling the power company to "report" that it smelled like a gas leak all the time. The only upside was the waves at night would fluoresce blue from the bio luminescence.

 

[SabrToothSqrl]

Hey! I'm on Back River in Essex.
My hull starts stark white every spring and turns brown over the season .

If you want easy: https://www.walmart.com/ip/Star-Brite-Hull-Cleaner-Gel-Spray-22-oz/51201194

or you can make your own like I do:

https://maximpulse.com/oxalic/

I load this stuff every fall into a pressurized spray container and go to town on my hull. it's literally the only thing that can touch this crap. Mix it as 'gentle' as you can. but I've not seen any negative affects from it. Be safe. it is ACID.

Once you spray it on, wait a few, then brush or hose it off, should be bright white again.

I've been doing this for a few years - it doesn't seem to harm the fiberglass, but if you can I would wax it after if possible. I hate this brown line crap. My last boat had a green hull (vs white) and it was 99% less visible.

 

[fitzpatl]

Alec A- Yes, it's killing fish, too. Neighbors around the corner are complaining about the stench.

SabrToothSqrl - Thanks for the rec. I like how easy that is.

I called Formula today and talked to ChrisE. He said they use Buff Magic from Shurhold. It looks like a very fine abrasive and requires a buffing.

He also said they use the 3M Wax products on the Imron all the time, which seems to conflict with what others have said about Imron. But Formula should know, right?

 

[rpm605]

been using this for 2 years on on my 2019 Formula 240 BR. works great, zero damage. My boat stays at Nabbs Creek and gets dirty after 4-5 days in the water.

https://www.westmarine.com/buy/star-brite--spray-gel-hull-cleaner-32oz--15940000?recordNum=1

 

[Botjem]

A few members in my club are using toilet bowl cleaner and I have seen the results and it does work. i just think it is very caustic.

 

[Nate]

Starbrite EZ on EZ off will take it right off. Make sure you don't get most of the cleaners that have been suggested on metal.

 

[robcam]

https://slimygrimy.com/

This stuff is amazing, can have in a day via AMAZON.

 

[SabrToothSqrl]

"Customer Questions & Answers - Amazon.com

www.amazon.com › ask › questions



Slimy Grimy boat hull cleaner is made from Oxalic Acid. If mixed to the right concentration it should be safe to use on a fiberglass hull similar to the commercial ..."

That's all any of these are... you can make your own much cheaper.

I mix mine up, acid + hot water + dawn to make it stick.

I put it in this:
https://www.lowes.com/pd/Chapin-1-G...ViJWzCh0T0QgNEAQYAyABEgJN-fD_BwE&gclsrc=aw.ds

spray on the hull. wait a bit, and rinse it off.

I've only done it 1x a season - at the end on a trailer. I don't bother during the season, but I swear I lose 5mph by the end of the season due to the brown crap on the bottom.

 

[PJ]

I use this stuff once in awhile. It?s $2-$3 at Walmart et-al.
Melts the brown stains off. Really really fast.
Not eco friendly or aluminum anything friendly or skin friendly.
Need to rewax hull.
On the plus side hull will be corona19 free