Formula B is my first choice. I've used this many times. Used according to the direction, it prevents mold from coming back.
https://www.practical-sailor.com/blog/homemade-mildew-preventers-that-really-work On carpet you use a vacuum to extract the dirty water.

Bleach can help with stains. It can also ruin fabrics. Do not use over recommended concentrations; it does not clean better, it only makes it more dangerous. Adding a little TPS to the bleach can help it clean (NOT TSP substitute--that isn't TSP). In general, do NOT add anything to bleach unless you know exactly what it does. Ammonia (chloramine)and vinegar (peracetic acid) are big no-nos with bleach). But I don't use bleach on boats because it really doesn't work that well.

No, you do NOT rinse with fresh water after Formula B. You rinse with the same solution, because the residue is the preventative.

A sponge is not really a cleaning tool, it is what you use to suck up the water when you are finished. A brush is for scrubbing.

Allow the chemical to work for 10 minutes. This helps a lot no matter what you use. Immediately scrubbing is a waste of elbow grease. Work smart.

As for environmental harm, consider that a dilute solution of bleach is basically chlorinated tap water. The main thing with cleaning chemicals is to use no more than what is needed. One of the most common mistakes is thinking that more is better.

 

Formula B is my first choice. I've used this many times. Used according to the direction, it prevents mold from coming back.
Homemade Mildew Preventers That Really Work - Practical Sailor On carpet you use a vacuum to extract the dirty water.

Drew,
PS seemed to favor Formula A (I thought you were the tester). Or am I mistaken? Any thoughts about the effect on teak faced plywood cabinetry? I've got a patch with the dreaded black spot...

Thanks.

 

The problem with mold, especially infestations like the OP describes, is they grow in places you can't reach or even see. You kill and clean off all the visible mold, but the colony behind the cabinetry or cabin sole or tankage continues to grow and infiltrate.

I'd bomb the boat with something like chlorine dioxide. An oxone generator is controversial and, while I've read all the pros and cons, I come down on avoiding it. You still have to clean the visible surfaces.

 

An oxone generator is controversial and, while I've read all the pros and cons, I come down on avoiding it. You still have to clean the visible surfaces.

Just wondering what the controversy is about ozone generators? I have never used one, and have never had a reason to use one. But aren't all the C-Pap cleaners based on an ozone generator?

 

Any surface cleaning product and a stiff brush will remove mold and mildew. Then the trick is to prevent the mold from returning. Low humidity and ventilation are the best option but not always possible, so clean surfaces at least once a week, and ventilate even if the boat is in a high humidity region.

Mold spores are in the air and will grow on surfaces if conditions are favorable.

 

Howdy,

You're dealing with exactly the same problem I am.

Yesterday I tried a few things

1) 10% Acetic acid (cleaning vinegar) diluted with water 1:1
2) Bleach diluted with water 1:1
3) "Mold killer" spray

I found that the vinegar doesn't do much to remove mold.

The bleach was a night and day difference. Sprayed it -everywhere- using a garden sprayer. Got it into absolutely every nook and cranny, in all the cabinetry, all fiberglass surfaces. The mold just melts off the moment you spray it with the bleach mixture. Use a respirator designed to handle bleach and bleach fumes, the fumes are terrible. Wear sealed eye protection i.e. swimming goggles.

We vented the boat out with a fan and every hatch open. The bleach mixture dries out quickly on a warm day.

There was only one place on the boat that didn't come clean on the first spray of bleach, an area that probably hadn't been cleaned by the past owner for 10+ years. The wall was completely black. With the first spraying of 1:1 dilution bleach, it cleaned up to a light cream color. One or two more sprays followed by a light scrubbing will probably clean it up and get it back to pure white.


Vinegar won't clean up the mold well, but it does prevent new mold from popping up and the fumes are a lot easier to handle. The smell disappears quickly with good ventilation. Spray down surfaces regularly with a vinegar / water solution and wipe down to prevent mold from popping up, and as everyone is mentioning, keep air moving through the boat to keep it dry and prevent mold from settling. Mold will only start to pop up if it has both moisture and still air so that the spores can land and attach onto a surface.

Environment-wise, bleach breaks down into salt and water, with a very small percentage (3-5%) of relatively harmless chemical compounds remaining.

 

Howdy,

You're dealing with exactly the same problem I am.

Yesterday I tried a few things

1) 10% Acetic acid (cleaning vinegar) diluted with water 1:1
2) Bleach diluted with water 1:1
3) "Mold killer" spray

I found that the vinegar doesn't do much to remove mold.

The bleach was a night and day difference. Sprayed it -everywhere- using a garden sprayer. Got it into absolutely every nook and cranny, in all the cabinetry, all fiberglass surfaces. The mold just melts off the moment you spray it with the bleach mixture. Use a respirator designed to handle bleach and bleach fumes, the fumes are terrible. Wear sealed eye protection i.e. swimming goggles.

We vented the boat out with a fan and every hatch open. The bleach mixture dries out quickly on a warm day.

There was only one place on the boat that didn't come clean on the first spray of bleach, an area that probably hadn't been cleaned by the past owner for 10+ years. The wall was completely black. With the first spraying of 1:1 dilution bleach, it cleaned up to a light cream color. One or two more sprays followed by a light scrubbing will probably clean it up and get it back to pure white.

Vinegar won't clean up the mold well, but it does prevent new mold from popping up and the fumes are a lot easier to handle. The smell disappears quickly with good ventilation. Spray down surfaces regularly with a vinegar / water solution and wipe down to prevent mold from popping up, and as everyone is mentioning, keep air moving through the boat to keep it dry and prevent mold from settling. Mold will only start to pop up if it has both moisture and still air so that the spores can land and attach onto a surface.

Environment-wise, bleach breaks down into salt and water, with a very small percentage (3-5%) of relatively harmless chemical compounds remaining.

You REALLY do not need to use chemicals at such high concentrations. Read the instructions! There is no reason for bleach to EVER be more than 1:20 in water. Small wonder it was killing you. Really.

The borax mixture described above is more effective at preventing the return. In fact, mold can eat vinegar once it gets diluted over time. Additionally, Formula B has no odor and only very minor skin contact risk. Try it. If there are still stains, then a weak bleach or shower cleaning solution will do it.

 

+1 for the formula B from practical sailor. I've been having a mold problem, all of a sudden, not sure why. We have a solar fan in the forward hatch, and a small dehumidifier running 24 7. Never had this problem before. I cleaned the interior with formula b, and ran an ozone generator for 4 hours. Did that last week, all looks good so far, hopefully that'll be the end of it.

 

It seems to me that the first order of business is to take whatever measures necessary to DRY THE BOAT OUT. Until that is done, all the disinfecting ideas shared here are simply band-aids.

Open the boat up on dry, sunny days. Or use small electric heaters to pull the moisture out of the wood and whatever else that might be holding moisture.

 

I agree with drying the boat out, if it's wet. Not sure I saw that noted. If electricity is available, I'd use dehumidifiers. Space heaters will increase the air temp in the cabin, which allows it to hold more moisture. That may help wet things to release some moisture, but could transfer it to others and there is a constant high humidity environment, unless the air is replaced with dry air.

 

3% hydrogen peroxide, simple and cheap. Add a little boric acid and you will help prevent it from coming back. If you add boric acid, try not to get it on your skin - it can cause issues if over exposed. Bleach, borax, and most other mold removers break down into this or that and water and SALT. Where there is salt there will be moisture and moisture breeds mold.

 

Borax and boric acid don't break down into anything. Think for a moment just how long the borax deposits have been exposed the elements. A borax film with prevent mold until it has been washed away or rubbed off (I've done the testing), regardless of humidity... but dry is always better because it will rub off eventually.

 

3% hydrogen peroxide, simple and cheap. Add a little boric acid and you will help prevent it from coming back. If you add boric acid, try not to get it on your skin - it can cause issues if over exposed. Bleach, borax, and most other mold removers break down into this or that and water and SALT. Where there is salt there will be moisture and moisture breeds mold.

Borax and boric acid don't break down into anything. Think for a moment just how long the borax deposits have been exposed the elements. A borax film with prevent mold until it has been washed away or rubbed off (I've done the testing), regardless of humidity... but dry is always better because it will rub off eventually.

You might want to give this a read. Borax is not pure boron.
https://www.boricacid.net.au/six-reasons-why-boric-acid-is-better-than-borax/

 

I should have also mentioned that while peroxide will kill mold, it will not remove mold stains.

 

I admit I don't know a thing about mold and have never cleaned it from inside a boat. That said, I love just about every cleaning product I have gotten from Bio-Kleen (the Black Streak Remover is amazing }. All their products are environmentally safe, biodegradable, and non-aerosol. I searched their site for mold. Looks like they have somethings that would be worth a try.

 

I call baloney on the "safe" claims, at least in part.

Most of their SDSs says "withheld " on most ingredients and "not known" on most environmental and health effects. Smart money says they use the same chemicals as everyone else and are at least exaggerating. The implication is that other products are "unsafe" without basis.

https://www.biokleen.com/SDS/SDS-Bio-Kleen-Black-Streak-Remover.pdf

I know companies are concerned about reverse engineering but (a) you need to back up claims and (b) your competators with analyze samples if they are actually curious.

 

^^ If it came across as an insult to you I did not mean it that way. It's just a pet peeve.

What bugs me is unsupported claims and bottles that don't list ingredients. If safety is suposed to be important to the customer, then TELL THE TRUTH. An more green than what? Hydrochloric acid breaks down into salt, but it does lower the pH of the water. An orgnanic acid (say citric acid) is biodegradeable, but it also lowers the pH and has a COD demand. Perhaps it is safer on your skin, but is it better for the environment? No, obviously not. But the maker will claim it is "natural." So is hydrochloric acid, your stomach is full of it.

In the case of Bio-Kleen, if you can't list ingredients AND make bold claims, that's is a hard pass.

 

I never have done mold cleaning in my cabin but thinking to have mold removal asap after reading the whole discussion.

 

Lots of good advice on this thread. Just adding two cents because I have had some good results. I don't know about the environmental angle but I've been impressed by two starbrite products. I recently used their chlorine dioxide bomb and it absolutely removed all of the musty smell in the boat. I have also used their mildew stain remover and the amazing thing is that the mildew in places I used it has not come back in 2 years. Takes a lot of elbow grease to get the the mildew off initially with this product though.

 

MOLD AWAY at Home Depot is great.