Everything You Need to Know to Keep Your Boat Mold and Mildew Free

Mold and Mildew – A Boat’s Silent Killer

To us, boating is the most rewarding and enjoyable experience life has to offer. The only downside is the never ending maintenance and repairs. There is nothing worse than taking the cover off your boat and finding your upholstery covered in mold or your cabin smelling musty. We’ve spent years cleaning mold and mildew from boats, and We’ve learned a few simple tricks that work extremely well.

The key to controlling mold and mildew on your boat is to prevent water from accumulating within enclosed spaces. Proven methods to remove moisture include using exhaust fans, heaters, dehumidifiers, and silica gel. Fresh air and sunshine are two very effective ways to kill mold and mildew. Anti-mold sprays and household chlorine also work very well.

Just like any other asset, you want to make sure your boat is properly maintained so you can continue to enjoy it for years to come. Boats must be cared for differently than your car or home. If you forget to wipe your boat down or store it in a damp area, you may get an awful surprise when you arrive at the dock for a day on the water. Besides the foul odor and unattractive look, mold and mildew can cause allergic reactions and even serious illness. Not mention, they can damage your boat’s upholstery and painted surfaces. Fortunately, there are some effective ways to deal with mold and mildew that don’t cost a fortune or take a lot of time to do.

How can mold and mildew get inside my boat?

Mold and mildew both thrive on moist, damp, and poorly insulated areas. When your boat is stored for the winter or whichever season you won’t be using it, there are many ways that mold and mildew can start to appear. If you don’t perform routine inspections on your boat while it is stored, you are allowing a problem to be there and you won’t even know about it.

We have found that leaks can happen if you don’t have a canvas cover with a proper ventilation system. A good quality canvas boat cover that allows fresh air to get in, without rain water seeping through, will save you headaches and money in the long run.

There can even be some cracks or leakage around windows that you didn’t have previous knowledge of and that can lead to water getting in and causing not only the water damage itself but mildew and mold as well. Furthermore, the snow can actual pose a problem if you don’t have the proper coverage for your boat while storing it. If you are using a cover that doesn’t have a ventilation system, has some rips or tears, or isn’t designed/manufactured to cover a boat, water can get in once the snow starts to melt.

How do I prevent mold and mildew from growing on my boat’s vinyl and canvas surfaces?

Mold and mildew are the nasty culprits that can ruin the interior of a boat and cost you money to repair. The problem can start out small but if it goes unnoticed or untreated, it can spread and become a bigger one. Prevention is the key to avoiding mold and mildew: perform maintenance and inspections.

We recommend you do a monthly check on your boat to ensure everything is working as it should and looks the way it should. It is critical to check for any leaks, standing water, and is definitely a good time to air the boat out.

Here are a few ways to help prevent mold and mildew:

• Fans. A fan is a good option because it allows the air that does come in, to circulate throughout the boat. Without air circulation, you are inviting mold in and giving it the perfect atmosphere to grow and spread to other areas, thus, causing more damage.

• Heaters. A heater is also great for helping to dry out any moisture that may already be there and preventing any moisture from appearing at that present time.

• Silica gel. You may have seen silica gel packets in new products you have purchased such as purses, backpacks, shoes, etc., and may have not known what they were for. Silica gel absorbs water vapor in these dark places and this prevents any mildew or mold from growing there. You can place silica packs in any closed in areas of your boat, to help prevent any moisture buildup.

• Anti-mold spray. Spraying down your vinyl and canvas surfaces with an anti-mold/mildew product, will prevent anything from growing there or killing what may already be present.

• Fresh air. Enclosed spaces need air just like we do. Airing out your boat will enable moisture to not linger or even form at all. Mildew and mold both love poorly ventilated areas so keeping your boat ventilated will stop them before they even have a chance to appear.

• Sunshine. The sun is the perfect way to dry areas of your boat. Whether it be the seats when you have cleaned them or when you hang out your canvas cover to dry after cleaning.

What items need to be protected?

Life jackets. Vinyl is one of the common materials used in life jackets. Just like with your boat, if you don’t take care of your life jacket, it can end up with mildew or mold in or on it. When you have finished using a life jacket, rinse it and let it air dry. Check the entire surface area to ensure there are no rips or holes. These are openings for water to get in and if left inside, can cause mildew and mold.

Boat cover. The cover is made of canvas and it can be susceptible to mildew and mold. Make sure to clean your canvas on a regular basis. This helps kill anything that may be growing and prevent any if there are none there. Lay the cover on a flat area and use a marine grade canvas cleaner. Spray the entire surface area and gently brush the entire canvas(front and back) and rinse it. Once it has been rinsed, hang it so that both sides may dry. This is great to do before storing your boat, when inspecting your stored boat, or if you are taking your boat out of storage for the season.

Seat cushions. Seats are a breeding ground for mildew and mold due to it raining while on the boat or sitting after going for a swim. It you do notice your seats are wet, I suggest doing a wipe down right then and there. If you can find a way to keep them dry every chance you get, that will keep mildew and mold from having a place to grow. Also, when storing the boat, if yours permits, flip up seats to prevent any mold or mildew from possibly growing underneath them.

Bedding and mattresses. Use a mattress that has the ability to let air flow underneath it or use a mattress protector designed to be waterproof and protects against allergens. If you are removing the mattress to store separately, clean it first and let it completely dry before putting it away. The same goes for bedding. If you are removing the bedding to store, wash it, let it fully dry, and then store it. Also, if you are removing these items from storage, I would also recommend cleaning them again before using them.

Vinyl roof and canvas t-top. Find a marine grade cleaner and clean your vinyl roof and canvas t-top with it. This is a preventative measure, especially if done on the regular. Properly cleaning will prevent anything from attempting to grow or kill what is already growing.

Is there any way to fully prevent mildew and mold from growing on my boat?

There isn’t a way to completely prevent mold, especially on a boat. There are steps to take to try to avoid dealing with mold but the bottom line is, you may experience mold at some point if you have a boat. The main thing to do is to take preventative measures to try to be ahead of the problem before it starts or at least catch it in its early stages.

Protect Your Boat Cover

Your boat cover is one of the primary protectors of your boat when it is not in use. In order for it to be the protector it needs to be, it must be in tip top shape itself. Protecting your boat cover can be the difference between a damp/wet interior and a dry/well ventilated one. Make sure you cover is cleaned regularly, check it for holes or tears, and if it has a ventilation system, make sure it is working as it should.

How often should I clean my seats and cover to prevent mold growth?

I strongly recommend at least giving your seats and cover a cleaning every month but if you do use your boat a lot, you may want to do a quick wipe down after each use. Treating the problem before it starts is wise. If you do small things routinely to properly care for your seats and cover, it will save you money in the long run.

How long will it take to clean my seats and canvas, to prevent mildew and mold growth?

The process is easy and doesn’t take long. The goal is to get the seats or canvas cleaned thoroughly and stop the growth of any potential mildew or mold from spreading further throughout your vessel. Simply spraying a cleaning product or mixture of your own on these areas, thoroughly rinsing, and fully allowing everything to dry, can take mere minutes but save you hundreds of dollars.

What is dry rot and how can I prevent it?

Dry rot is a term that comes from wood being wet. It is a fungus that thrives on moist/damp/wet areas and will slowly rot the wood completely. It spreads quickly and damages any wood it comes into contact with. If your boat is made of fiberglass, you may think you are safe. In reality, you aren’t. Your boat will most likely have wooden stringers and wall studs. Once water has hit them, the fungus can take as little as 7 days to start reeking havoc on the wood.

The signs of dry rot include brittle wood that can crumble when you touch it, there may be an unpleasant odor, or you may see patches of rust colored dust. If you do catch the dry rot in its early stages you can use a fungus killer(boric acid) to treat the problem. If it is too late, you must cut out all of the damaged wood and replace it with pre-treated wood. This can be a costly process which is why it is important to do regular routine check up.

What products can I use to remove mildew, mold, and dry rot?

There are many marine grade products on the market to help fight and/or prevent mildew and mold. There are also remedies you can do with items you may already have in your home like: vinegar, boric acid, baking soda, tea tree oil, and hydrogen peroxide.

Vinegar can be mixed with water to create a solution to clean the mold. Add 3 parts vinegar and 2 parts water to a spray bottle and disperse it onto the area. As it sets, the vinegar will kill the mold.

Boric acid and water mixed together creates another solution that not only kills mildew and mold but also kills the fungus that causes dry rot.

Baking soda can be added to water and lightly scrubbed onto the problem area to remove and kill the mold. Tea tree oil is naturally antibacterial and anti-fungal. When a few drops are added to some water, the mixture can be sprayed on the problem areas and lightly scrubbed away.

Lastly, hydrogen peroxide mixed with water(1 part hydrogen peroxide and 3 parts water) can also clean mildew and kill mold.

Bleach has been the topic of discussion for cleaning and killing mold on boats. Some say it is fine to use sparely and others say it’s a big “NO”. We, personally, think it’s a “NO”. Bleach is a very powerful and harsh chemical that may discolor vinyl and canvas, corrode fittings, and will only kill mold on the surface.

Will boat insurance pay for damage caused by mildew and mold?

The short answer is no. Insurance companies know how common some extent of mold is in a vessel that is made to be on the water and also stored for long periods of time. Storing something that is used on the water means water could have gotten in and mildew and mold can form or continue to grow. Since almost all boats will have some from of mildew or mold in their lifespan, it would be too costly for insurance companies to pay for all of the damages to every boat.

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