​Q: There are several deck brushes to choose from at my local boating supply store, but I can’t imagine I need one of each. Which one or two do I absolutely need on my boat?

This week’s question is about mildew. Boat owners email me every year around this time asking how to clean mildew out of their canvas, non-skid and teak decks and how to keep it from coming back so soon.

As I’ve always said, dirt and mildew is the one constant in boating. It doesn’t matter if you have a six million dollar yacht, an old wooden boat or a new sailboat, mildew doesn’t judge! It will find your boat, attach itself to your canvas, teak decks, window sills and non-skid, and will quietly grow and multiply while you sleep. However, you can try to outsmart it and keep it from taking over with these simple tips on cleaning and removing mildew and then preventing it from coming back.

Keep in mind that there are two types of mildew or mold. Green mildew is what you’ll find growing in fabrics, such as canvas, vinyl edges and seams and on deck carpets. You’ll also see it on teak decks. Black mold is what you’ll find growing on vinyl cushions and in non-skid. If your non-skid has small black specks in it that don’t come out with just soap and water, that’s black mold. This article is discussing how to remove mold and mildew from exterior surfaces and materials. If you find any black mold growing inside the cabin of your boat, you can use many of these same tips and products, but the most important thing is to wear a respiratory mask when cleaning black mold from an enclosed space. It is known for causing respiratory problems and is not something you want to breath in for any length of time.

Mildew In Canvas
Canvas is one of those materials that mildew grows quickly in and if not removed in a timely manner, can become quite difficult to kill and remove down the road. It will grow rapidly around the edges and on the underside of the canvas enclosure of your cockpit or fly bridge. If not caught in time, it can also grow in the seams around the plastic windows and zippers. But you don’t need me to tell you all of the places where it can grow. You need to know how to get rid of it!

The first step is to gather the products you’ll need before you head down to your boat so you can kill the mildew and treat your canvas in one trip instead of having to come back several times and turning it into a larger project than it should be. Here is a list of the products you should have on hand:

• Small scrub brush – sort of like a really large toothbrush, sold in the cleaning aisle at any grocery or variety store
• Rubber gloves
• Mildew cleaning/killing spray such as West Marine’s Pure Oceans mildew spray (biodegradable and less toxic) or Lysol or Tilex mildew cleaner
• Boat washing gear (soft deck brush, boat soap, bucket, hose, nozzle)

When treating mildew in canvas, you need to be able to see exactly where the mildew is, so don’t wet down the canvas or wash it first, otherwise the canvas will darken from the water (unless it’s white) and you may not be able to see exactly where the mildew is. Take your mildew killing spray and spray it directly on all areas where you see mildew. If it’s on the underside of your canvas enclosure, spray the mildew killer on a deck brush or hand brush and then wipe the brush over that area. You may need to go over it a few times to remove all the mildew, but you don’t need to wipe it down afterwards, as it’s fine to leave some of the product in the canvas to help keep mildew at bay for a while.

If there is mildew around the edges of your canvas, spray those areas liberally with the mildew spray and let it sit in for a few minutes. Then take the small scrub brush and scrub those areas well, trying to get in the seams as best you can. You’ll know it’s working when you see green streaks running down the side of your boat from all of the mildew that you’re scrubbing out of the canvas. Hose the canvas off so you can see your progress and hit that area once more with the mildew spray and scrub brush. When done, wash your boat and rinse well so there are no green streaks still running down from the canvas.

Once you’ve removed the mildew from your canvas, you can use a product such as Mold Off to spray on your canvas in the areas where mildew grows. Spray it on and walk away and let the product do the work. It won’t harm your canvas to leave it on and will help keep mildew away for months at a time.

Mildew In Non-Skid
Black mold in non-skid will look like small black specks that aren’t coming out with soap and water. It’s actually quite simple to treat black mold in non-skid. Spray your mildew killing spray over the non-skid and then let it sit in for a couple of minutes. Then take your medium-grade bristle deck brush and run it over the non-skid, working the spray in. You don’t need to hose the decks at this time because you want to spread the mildew spray around, having it treat the black mold in its full strength before diluting it with water. It will suds up a little while you’re scrubbing the decks.

When finished, you’ll see the black specks disappear. If you want to be environmentally friendly, take some old towels and sop up the mildew spray on your decks before hosing them down. (If you choose this route, you may not need to hose them down at all.) Otherwise, hose them down well as to dilute the product running off your boat. Left to dry on your gel coat, the mildew spray can remove wax in that area and make it look streaky, so spend plenty of time rinsing the product off your boat.

Mildew On Vinyl Seats and Deck Carpets
You may find black mold on your white vinyl seats or green mildew growing around the edges or undersides of your vinyl cushions or on your deck carpets. The best way to remove the mildew on vinyl cushions is to spray it with the mildew spray and let it sit in for a few minutes. Then take the small scrub brush and scrub the edges or undersides clean. When done, wipe the area well with a rag, but don’t hose them down or they’ll be wet and susceptible to mildew all over again.

If there is black mildew on top of the vinyl seat cushion, spray with the mildew spray and let the bleach in the product do the work. Over the course of a few minutes, the black mildew will lighten up and eventually disappear. Wipe the cushion with a rag to remove the mildew product.

Treating green mildew in deck carpets is very easy. Simply spray the mildew spray over the area that’s green and walk away. Or you can sit there and watch the green mildew disappear, but it will take about 10 to 20 minutes. You don’t need to rinse or wipe it down because it’s alright to let the product stay on the deck carpets to prevent mildew from growing in that same area in the future. It may come back eventually, but you only need to repeat this process to remove it again. This is another area you can follow up with the Mold Off product to help keep mildew from growing back.

Mildew In Teak Decks
If there is green mildew growing on areas of your teak decks and you’re not planning on cleaning and brightening them with the two-part teak product, but instead just want to remove the mildew in the few places its growing (probably along the edges of the teak), you can do so with a soft scrub brush and some mildew spray. You don’t want to use a scrub brush that is too stiff, so if you rub it on your face or the back of your hand and it feels too scratchy, then don’t use it on your teak.

Spray the areas where there is green mildew with the mildew spray. Let it soak in for a few minutes and then take the soft scrub brush and scrub it over the teak going against the grain. Because the brush is soft (it has to be for the good of the teak) and the mildew has grown into the grain of the wood, this process is going to take some time. You may need to scrub a section for several minutes to start seeing any difference or you may need to come back and treat this area a few more times over the course of a few weeks. When done scrubbing the mildew out of the teak, hose it down well to remove the bleach from the grain of the wood and rinse the green mildew streaks off your boat.
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Cleaning and removing mildew from your boat can become an overwhelming project if you don’t stay on top of it, but if you treat it a little at a time and use the right products, you can keep it at bay long enough so it doesn’t get the chance to grow quickly and multiply to the point where you have to mow your canvas. Good luck and happy boating!

​Q: Should I use a black streak remover product or something similar to remove water streaks on my boat or just stick to boat soap?

A: The answer to this question will lead you in circles until your head spins. Yes, you can use black streak remover products to remove water streaks, but over time, they will strip the wax in those specific areas and then the water streaks will become more noticeable and difficult to remove. But if you wax your boat every year, then by the time those water streaks have become stubborn to get off because the product you’ve been using has completely stripped the wax in those areas, it will be time to wax your boat anyway.

Or I could have answered this question advising you to stick to boat soap, which will remove the water streaks for as long as you have a good coat of wax on your boat. Once boat soap stops removing the streaks, then you know it’s time to wax your boat again. In other words, a black streak remover product is a great band-aid and will hide the symptoms, but in the end, it too will stop working and that’s when it’s time to wax your boat again.

My advice is a happy medium solution to this. Go ahead and use the black streak remover so your job is easier in removing those black streaks. But as soon as they become a bit harder to remove with the product, then take some cleaner wax and reapply it where the black streaks occur. This is something you can do by hand with a rag to apply it with and a rag to buff or wipe it off with. This will help your big yearly wax job last a bit longer.

​Another option is to use a boat soap with wax in it. This doesn’t mean that as you wash your boat, you’ll be waxing it at the same time. This means that this type of boat soap doesn’t strip wax and adds a light UV protectant that should last between washes to help protect your boat that much more from harmful UV rays.

Q: When I bring my boat back from being in salt water, is hosing it off good enough?

A: No. If you have just arrived at the marina and only have a few minutes before you have to rush off to your dinner reservations, then go ahead and hose it off as much as you can, spending any extra few minutes you have on windows – both glass and plastic. But you are not off the hook. Go enjoy your dinner, but know that you still have work to do. If it truly is evening and the sun has gone down or it’s a cloudy day, then you’ve just bought yourself some time. But if your boat is sitting in full sun, your boat needs a lot more work than just a quick hose down. This is one of those instances where putting off what needs to be done can create permanent maintenance issues in the future.

Now that I’ve scared you into action, you really do need to give your boat a full wash after each salt water adventure. As soon as the sun hits your salty boat, it can burn those salty water spots into your gel coat and especially your glass and plastic windows. It can also start to rust your stainless, so time really is of the essence. Glass windows can show permanent water spots if they don’t get cleaned thoroughly and properly and once the water spot has been burned into a window, it is very difficult to remove. You can’t clean it away with a window cleaner and you can’t even pick it off with your fingernail. Unlike other water spots, you can actually see the edges of each spot created by salt.
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So, to keep your head from spinning, wash your boat with boat soap or Salt Away and water. Hit all sections – gel coat, non-skid, glass and plastic windows and stainless. When you’re done, wipe down all windows until they’re dry. You can do the same with stainless if you have time, but the windows require your attention more than anything else.

Q: The spiders at my marina are horrible. What can I do to keep them off my boat?

A: Ah yes, spiders. Not only are they creepy, but they leave little black dots everywhere on your boat – in your non-skid, on your white vinyl seats – everywhere! How is it possible for such a tiny creature to take over your boat almost no matter what you do to stop them! Thank goodness you can win the war over spiders, but you will need to be diligent. There is no solution that you can just set up and walk away from never to have to worry about it again. However, here are three solutions that will help you today and for a while to come.

1. Use a fogger. We've used the Hot Shot fogger inside boats and it's worked really well. This is the kind of insect fogger you set off and then run out of the room and stay away for about four hours. When you come back, all you see are dead insects everywhere – but at least they’re dead and no longer reproducing! This is the best solution to use in an enclosed space, such as inside your canvas enclosure or inside your boat. Afterward, you will need to clean all surfaces to remove any residue and you’ll want to vacuum up all the dead insects. Foggers not only kill the live insects, but their eggs, as well, so your enclosure will be spider free for about two months.
2. Use spider repellent. We love this all-natural Mighty Mint spider repellent because it actually works, smells good and isn't toxic to humans or pets. This is a product you can use anywhere on or around your boat. Spiders get onto your boat by climbing up your lines, so spray your lines and around the dock area, such as your dock box, fenders and the edge of your dock. Use it to also spray around the edges of your canvas enclosure and the inside corners where they like to hide and build nests. Although it’s advertised as a natural products, I still wouldn’t advise breathing it in, so either cover your mouth and nose or wear a mask. If you spray this every few times you visit your boat, it will do a good job of keeping spiders at bay as it kills them soon after contact and it repels them for a few weeks.
3. Use an ultrasonic spider repeller. There are many different brands and types, but we've had great results with this ultrasonic spider repeller. You simply plug it into an outlet on your boat, inside or outside, and it emits an ultrasonic sound that apparently only spiders are affected by. It disrupts their living conditions and causes them to find a less annoying home somewhere else (aka - your neighbor’s boat). This type of device works fairly well and will keep spiders off your boat for a few months, but you’ll need to buy a few different brands and switch them up each time. Otherwise the spiders will get used to the frequency over time and eventually not be so disrupted by it.

Want to learn more about spiders and how to rid them from your home? Here's an article showing pictures of different spiders (great way to know the ones you really need to worry about) and a company that can make them disappear.

Q: I’ve heard MEK or acetone is great for removing marks in gel coat. Is it OK to use or will it ruin the gel coat in any way?

A: I would save strong chemicals such as MEK or acetone as a last resort gel coat stain remover. First try a multi-purpose, biodegradable cleaner such as Pure Oceans All-Purpose Spray or even Simple Green in its more concentrated form. If the mark or stain isn’t coming off with a spray cleaner, then try a cleaner wax or rubbing compound. Just squeeze a small drop of it on a cloth and try rubbing the stain away. Remember that there is no wax in rubbing compound, so if you use it to remove a stain, you’ve also just removed any wax that was in that area, so you’ll want to apply another layer of wax for continuous protection.
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If those things aren’t working and you want to try a stronger chemical such as acetone or lacquer thinner, then just pour a small amount of it on a rag and wipe it over the stain. These types of products will probably remove the stain, but consider that they’ll also remove any wax in that area, just as the rubbing compound will. This won’t hurt the gel coat in any way, but if you use strong products like this on gel coat, always follow up with another coat of wax in that section.

Q: Can I use my car detailing products on my boat? What about home cleaning products?

A: Yes and no. There are some products that are meant for autos and home and some that can be used anywhere. First, make sure the product is biodegradable if you’re going to use it on your boat. Second, decide where you plan to use this product on your boat. If you’re cleaning the interior of the boat such as the cabin, staterooms, head, galley, etc, most of your home cleaning products can be used in those areas because the finishes are similar between boat and home, such as wood paneling, granite countertops, mirrors, fiberglass tubs and showers, glass windows and carpeting.

However, there are a few areas inside your boat where you won’t want to use general home cleaning products and those areas include the sink, toilet or shower drain. If you’re going to be pouring something down a drain, stick to a marine product so as not to dry out or cause damage overtime to any drains or connections.

For exterior cleaning, such as washing and waxing, it’s often best to stick with products meant for a boat rather than a car. Waxes, compounds, polishes and buffing pads meant for automobiles are designed to work with clear coat rather than gel coat. It’s not that a polish meant for cars won’t work on your boat, but from those that we’ve tested, they didn’t do as good of a job or last as long as those meant for gel coated boats. When buffing clear coat, you typically use a foam buffing pad, whereas with gel coat, you want to use a wool compounding or polishing pad. Also, the manufacturers assume that you probably garage your car and a car takes much less time to wax than a boat, so to wax your car every few months isn’t too much of an undertaking. A boat sits out in the sun and takes a lot of time, labor and money to wax, so any wax used on a boat had better last at least 9 to 12 months.
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One tempting household product that should never touch your boat is dish soap. It removes wax and will dry out your gel coat quickly making it look faded.