This guide explains the best ways to prevent mold on your boat. Preventing mold is a concern anywhere there is moisture. Mold grows whenever, not wherever, there is moisture. Living on a boat means living on water, and that means preventing mold is a constant concern. Mold, especially the toxic kind, is a serious threat that can compromise a boat’s structural integrity and threaten the health of its occupants. Mold prevention is cheaper, healthier and easier than the results of infection. Here is how to best prevent mold that is simple and easy.
The six best ways to prevent mold: 1. Seal any leaks where rainwater can enter, 2. Limiting moisture indoors, 3. Properly ventilating your boat and ensuring sufficient air flow, 4. Cleaning on a regular basis. 5. Treat affected areas with borax. 6. Remove any structures where mold was growing. Caulk and reseal deck fittings. Keep humidity levels lower than 50%. Keep the air circulating as much as possible. Clean everything regularly. Wash all fabrics with borax. Remove all contaminated substrates, including wood and fabric.
What Causes Mold?
Mold spores are in the air everywhere all the time. Mold is a generic term for many varieties of fungus. This fungus will survive on any surface under the right conditions. There are three things mold needs to grow: food, moisture, temperature. Out of these three factors, moisture is the most easiest to control. According to the Center for Disease Control (CDC), suitable conditions for mold to grow include temperatures between 60-80 degrees Fahrenheit (16-26 C), humidity above 50% and an organic substrate, such as cotton, leather, wood and paper.
What Causes Mold to Grow?
Mold will flourish when the air is stagnant, and when humidity and temperature are high. This is why greenhouses with ideal conditions for mold of high humidity and temperature keep mold at bay with ventilation. Freezing temperatures only cause mold to lie dormant. Mold will continue to grow when warmer temperatures return. Likewise with low humidity. Mold growth will return when the humidity increases. Many mold varieties prefer dark conditions, but not all. Many molds prefer moderate pH, but some can survive at pH 2 and below. All molds require moisture for growth but the amount required varies widely. Nearly all moulds require air to grow. Some molds may thrive well with high sugar or salt content. Some molds prefer only simple sugars while still other varieties have the ability to consume rather complex sugars.
Mold Remediation and Treatment
If you have a problem that is widespread or covers a larger area, stop. Get professional advice. Breathing a concentration of mold spores can have long-term serious health consequences.
If you still want to tackle a big job by yourself, you should prepare ahead of time and have the right supplies. Open the area, ventilate the affected areas, use a heater or air conditioner or dehumidifier. At the very least, wear a mask, preferably a respirator and gloves. Do not breathe the stale air in a moldy area.
How to Best Prevent Mold
Seal All Deck Leaks
All boat decks have fittings for masts, cables, biminis, solar panels and more. Nearly all these fittings have drill holes where bolts are fastened through the deck. All of these holes are opportunities for rainwater, deck washing ocean spray to find a way into your boat. Gravity will help that water all it can until it evaporates.
If you have water seepage into your boat, you might be able to identify the source by observation during a rainstorm or have someone else wash the deck where you suspect there is a problem. You can also, try adding a temporary coloring to the water if you suspect more than one source. (Make sure you test first and don’t stain your boat.) If it has been several years since the fittings were caulked, consider systematically calking all the fittings. Remove the bolt, caulk the hole top and bottom, replace the bolt and tighten the nut.
Limit Indoor Moisture
Check all of the water intake areas, water storage devices and the wastewater returns. Make sure your boat is not holding any wastewater. Check the bilge, storage areas, water traps, under the sink and shower areas. Make sure your plumbing fittings are solid and don’t leak.
If you have a watermaker, check the fittings there and make sure all water returns actually work. If in doubt, put desiccants, water absorbers or humidity sensors in problem areas. Speaking of moldy places, be sure to check your air ducts.
Ventilate Your Boat
There are lots of ways to ventilate your boat, including fans, hatches, vents, opening portlights, or air-conditioning systems. Though probably everything is built-in already. If you have a problem area, you might want to consider installing a fan to circulate the air. Most areas of a boat are near other parts of the boat. It’s possible to install a vent to the deck and install a wind scoop.
Other options may include a dehumidifier or air conditioner. All of these – fans, dehumidifiers and air conditioners – use electricity, sometimes lots of it. Even on a solar positive boat, these later two will require extra power. However, there are newer models on the market that run on DC power, which is better than AC and more readily available.
Clean Everything Regularly
The cheapest prevention is to clean everything – surfaces, fabrics, appliances, decks, ceilings, furniture – on a regular basis. There is no substitute for hand washing. Every surface should be wiped down with a soft cloth and a cleaner. All furniture should be wiped with a soft cloth and a cleaning liquid. All fabrics should be washed and thoroughly dried.
Treat Affected Areas With Borax
Borax is an all-natural cleaner that can kill mold just as effectively as Bleach. Technically it is called sodium tetraborate, composed of oxygen, sodium and boron and is similar to table salt. You probably know of it as the twenty-mule-team brand of laundry cleaner, mined in central California. It is also valued as a flame retardant.
It is non-carcinogenic and natural. Borax is generally safer to use. You can paint a borax mixture or use it in a spray bottle. Make a borax paint by mixing half a cup of borax and 2 quarts of boiling water. You can also use a water-borax mixture using one cup of borax to 1 gallon of water ratio. Then, please put it in a spray bottle. It apparently works by changing the pH to alkaline.
Remove All Mold Supports
Most of your mold problem is invisible, or nearly so. What you see is the fruiting body of the mold. The roots may extend a hundred or a thousand times the size of whatever you can see. In addition, the appearance of mold means that the conditions are suitable for other mold growth. These roots will stop growing with treatments like dry, clean conditions. However, their existence is not healthy and they form the launching pad for an accelerated return as soon as conditions are favorable.
For this reason, you should consider removing all of the substrate the mold is growing on, including wood, paper, fabrics and other organic materials.
Mold Problems
Mold causes many health problems. Mold can cause symptoms like a stuffy nose, sore throat, coughing or wheezing, burning eyes, or skin rash. People with asthma and those who are allergic to mold may have even more severe reactions. Immune-compromised people and people with chronic lung disease may get life-threatening infections in their lungs.
There is always some mold. Unfortunately there is no way to completely remove mold from porous materials. Mold in the air outside can be brought indoors on clothing, shoes, bags, and even pets. It gets into your boat through open doors, windows, vents, and heating and air conditioning systems. Mostly, mold becomes a problem when the air is stagnant.
Mold grows on any organic material (and some non-organic surfaces) including cardboard, ceiling tiles, paper and wood. Mold can also grow on paints, wallpaper, in dust, insulation, fabric, carpet, drywall and upholstery. Mold will grow anywhere there is moisture, such as around leaks in roofs, windows, or pipes. It is a major problem after a flood.
Should I get Tested for Mold?
The CDC does not recommend testing for mold. Sampling for mold can be expensive. There are no set standards for what an acceptable levels of mold in a boat. You cannot rely on sampling and culturing. You or a family member might become sick when another will not. The health effects of mold are different for individuals. All mold is unsafe. No matter what type of mold is present, you need to remove it. The best thing you can do is to safely remove the mold and work to prevent future mold growth.
Cleaning Mold
Mildew is the beginning of mold. Mold can look like small dark spots. It can be many different colors, and it can smell musty. If you see or smell mold, there is most certainly more that you don’t see, and you should clean it immediately. You do not need to know the type of mold.
Mold is growing in every living environment, especially damp areas, including your boat. Mold is a part of any ecosystem, and it can be found in both indoor and outdoor air at any moment. With that in mind, you should be aware that you cannot create a 100% mold-free environment. What you can do is ensure that the concentration of mold spores in your indoor air remains minimal.
This decreases the chances of it actually multiplying and growing. You need to clean up the mold and fix the moisture problem as soon as you can. Mold can be removed from hard surfaces with household products like soap and water, or a bleach solution of no more than 1 cup of household laundry bleach in 1 gallon of water. (Don’t mix bleach and ammonia!)
If you don’t want to use bleach, try borax. I will discuss using borax below.
DO NOT MIX BLEACH AND AMMONA
Combining bleach and ammonia is lethal. It produces a poisonous gas that can kill you quickly! If there is any doubt. Clean the surface with soap and water first. You can also use borax instead of bleach. See below.
Cleaning Mold
Open windows and doors to provide fresh air.
Never mix bleach with ammonia or other household cleaners. Try borax.
Always follow the manufacturer’s instructions when you use bleach or any other cleaning product.
Wear rubber boots, rubber gloves, and goggles during cleanup of affected areas.
If you need to clean more than 10 square feet, check the U.S. Environmental Protection Agency guide. You can get it by going to the EPA web site at:
https://www.epa.gov/mold/mold-remediation-schools-and-commercial-buildings-guide-chapter-1
To Prevent Mold Growth in Your Boat
Keep humidity levels in your boat no higher than 50%. You can buy a meter to check your boat’s humidity at a home improvement store. An air conditioner or dehumidifier will help you keep the level low. Check the levels frequently because humidity changes during the course of the day.
Be sure the air in your boat flows freely. Use exhaust fans that vent outside your boat in the galley and head (bathroom). Make sure your clothes dryer vents outside your boat.
Fix any leaks in your boat’s roof, walls, or plumbing so mold does not have moisture to grow.
Clean up and dry out your boat fully and quickly (within 24–48 hours) after a flood.
Add mold inhibitors to paints before painting. You can buy mold inhibitors at paint and home improvement stores.
Clean bathrooms with mold-killing products.
Remove or replace carpets and upholstery that have been soaked and cannot be dried right away. Think about not using carpet in places like bathrooms or basements that may have a lot of moisture.
To learn more about preventing mold in your boat, see the Environmental Protection Agency’s book:
https://www.epa.gov/mold/mold-remediation-schools-and-commercial-buildings-guide-chapter-1
Common Problem Areas
Head (Bathroom)
Even though mold can grow practically anywhere, there are three areas of your boat that are the most common spots for mold growth. One of them is the head. You may see mold growing on tiles in places like the head. The good news is that mold can easily be cleaned from the non-porous surfaces of tiles.
Bathrooms tend to be very humid, and moisture is one of the main requirements for mold to grow. As such, if you want to prevent mold from growing in your head, you have to pay close attention to and limit moisture in your shower and/or bathtub, sink and even towels.
Bedroom
Fabrics are problematic for mold growth. They are also the most dangerous. Of all the rooms in your home, you spend the most time in your bedroom sleeping. For this reason, it is critical to keep mold out of your bedroom and ensure healthy air quality.
In a best-case scenario, your bedroom will be the room with the least furniture, leaving enough open space for air to flow. But in case it is not, consider re-thinking the purpose and functionality of all the things you keep there.
Galley (Kitchen)
Along with the head, the galley is also often the target of mold attacks. Of course, you don’t want mold anywhere near your food. Learning and understanding how to prevent mold in your kitchen will bring you a step closer to having a healthy life and a happy boat.
From how cooking causes mold growth to all the secret places you need to check, this is definitely something you wouldn’t want to skip.
Storage
You certainly have small storage areas on your boat. The small storage areas are where stagnant air can cause the greatest damage and where it can to the most harm because it will spread to the other areas of your boat rapidly. If you find mold anywhere on your boat, you will want to clean the storage areas thoroughly.
Mold loves dark and moist places and your storage areas can provide both. With that in mind, it’s clear that you will have to do some extra work to ensure your boat is mold free, but it is not an impossible job for sure.
Conclusion
Mold thrives in damp, dark places and can pose a serious problem for both health and property value. Aside from the occasional water leak, mold can be an indication of bigger problems. If you notice mold, remove the material immediately. Clean the surrounding area thoroughly. If the problem is bigger than a simple leaning, you should consult a professional.