Brrr, can you feel that? Before the cold winds of winter whip, you must prepare your pontoon boat for the impending season. This is known as winterization. Just exactly how do you winterize your pontoon boat?

To winterize a pontoon boat, you should do the following:

  • Clean out your boat
  • Take all removable equipment and accessories with you
  • Empty engine coolant and fill with antifreeze
  • Use fogging oil on your spark plugs and carburetor
  • Toss out old oil filters and add new ones
  • Keep your gas tank semi-full
  • Apply rodent/insect repellant as well as rust and mildew sprays
  • Put your cover on

If you’re looking for more information on the above points, you’ve come to the right place. In this article, we’ll go in-depth on how to winterize a pontoon boat. We’ll also cover the costs of winterization, what happens if you leave your boat out all winter, and more. You don’t want to miss it.

How to Winterize a Pontoon Boat

Cleaning the Boat

First thing’s first: you need to clean your pontoon boat. Make sure you dock your boat so you can give it a thorough wipedown inside and out. Don’t miss any surfaces, as you want everything prepped for the winter.

Taking out Removable Accessories and Equipment

As you clean, you want to take note of the items in your boat. If these are detachable or removable, then you want them out of the boat for the winter. All your possessions like clothes, blankets, cushions, and pillows should go. Your equipment for fishing or boating also needs to come off the pontoon. Any accessories like Bimini tops, detachable grills, and the like should not stay onboard for the winter season, either.

Don’t forget the battery! It won’t survive the winter, which means a dead pontoon boat in the spring.

Emptying Engine Coolant and Adding Antifreeze

Now you want to move on to your engine. There’s probably some coolant left in there from the active season. You want to empty your engine of all this coolant, draining it out.

To prevent the engine from freezing in the cold temps, you’ll need antifreeze. Not just any antifreeze will do. Double-check that you get antifreeze with propylene glycol in it. Anything but this isn’t the safest to use if you care about the environment. Antifreeze will leech out into the water. If it has ethylene glycol in it, then toxins will seep into your water supply, killing off the creatures in the water.

Fogging the Spark Plug and Carburetor

You’re not done with your engine yet. Once you pour in your propylene glycol antifreeze, you want to find the engine’s spark plugs and carburetors. Use fogging oil on both these components. Focus on the holes in the spark plugs as you spray.

Changing Oil Filters

Next, it’s time to give your oil filters some attention. Regardless of how recently you changed the filters, you want to take out the old ones. Add fresh filters. This way, these new filters can withstand the cold winter ahead.

Topping off the Gas Tank

You don’t want a totally full gas tank nor one that’s completely empty. Leave a little bit of gas in there so it’s about 3/4ths full.

Applying Repellants and Sprays

There’s a whole host of repellants and sprays you should invest in if you don’t already own them. A repellant for rodents and insects will keep these creatures away from your pontoon. After all, they might mistake your cover for a tasty snack, and if they eat through it, these pests will damage your boat.

If you’re worried about mice, we like Fresh Cab’s Botanical Rodent Repellant. Each non-toxic pouch will cover 125 square feet of your boat.

Rust can also occur during a long, arduous winter. Motorex’s Anti-Rust Spray will keep it away. A favorite among pontoon boat owners, this spray also prevents corrosion. It does this through moisture displacement. If rust has begun to accumulate on your boat, this spray can even get rid of it before it worsens.

Mildew and mold can accumulate if your boat cover creates a humid environment. This Mold Armor spray can clean away any and all traces of both types of bacteria.

Covering the Boat

Your last but most important winterization step is covering up your boat. The cover must fit perfectly for your make and model of pontoon boat. Keeping the cover down with bungees, cords, and zippers helps as well, especially during a rough cold season with lots of high winds.

How Much Does Winterization Cost?

If you’re a first-time pontoon boat owner, you might choose to let a professional take care of winterization for you (yes, such a service exists). You’ll generally pay $300 for this.

Even if you winterize your boat yourself, it’s not free. You have to buy a cover (more on this shortly), antifreeze, cleaning products, boat gas, repellants, anti-rust spray, and anti-mold and mildew spray. Covers don’t last forever, and so every few years, you’ll likely have to replace yours. All those costs add up.

Can You Leave a Pontoon Boat in the Water over the Winter?

What if you were to leave your pontoon boat out on the water all winter? Can you? Should you?

It depends on where you live. If you call a southern state home, then you probably have very mild winters at best. There’s no need to winterize your boat, per se. Instead, you should get an enclosure and a boat lift so you can safeguard the pontoon from rain and wind.

If you do have a proper winter where you are, then we don’t advise you to leave your boat in the water all winter. First, there’s always a chance the boat can become detached from the dock and get swept away.

Second, your boat’s bottom will get all grungy. Barnacles and other detritus can form on the bottom surface without a lift. Unless you can clean the bottom’s bottom every few weeks, you’ll come back to an unpleasant surprise once spring arrives.

Snow and Rain Covers: How to Choose One

As we mentioned several sections back, you need a cover for your pontoon boat. Otherwise, you’re exposing it all the elements, like sunshine, wind, rain, and snow.

How do you choose a pontoon boat cover? There are several criteria to consider:

  • Size: You need a cover that fits your boat to a tee. If your cover has excess loose material, the wind can lift and pull it, possibly causing rips. A cover that’s too small doesn’t adequately cover your entire boat.
  • Security: Many boat covers include zippers, bungees, and other means of securing your cover so it doesn’t blow away. Your cover should have these as well.
  • Sun protection: If your pontoon boat cover doesn’t have UV-resistant fabric, the sun can still damage your boat. Yes, its rays can permeate through the cover to your pontoon. Take the time to make sure you find a cover with UV-resistant fabrics.
  • Durability against snow and rain: You need strong fabric for your pontoon boat cover as well. When it snows and rains, the cover should withstand the weight without tearing or ripping. This keeps moisture out of your boat and also protects it from a mountain of snow or rain coming down on it.
  • Wind protection: Finally, your cover should have wind protection built in. Wind can cause stress on the cover fabric, eventually tearing it. You could come back in the spring to see your cover in tatters. No one wants that.

Does a Shrink Wrap Kit Suffice?

Some pontoon boat owners advise for wrapping the boat in a shrink wrap kit before putting a cover on. Is this a good idea or just a waste of your time?

It’s actually a fantastic idea! For this job, you can just use grocery-store shrink wrap. You’ll need several boxes of the stuff, as you have to cover your entire pontoon boat. You want to ideally do this after you’re done with all the other winterization steps but before adding your cover.

What does the shrink wrap do? Good question! The plastic wrap has two awesome functions. The first is reinforcing the strength of your pontoon boat cover. With the shrink wrap on and then the cover over top, your cover has a lower likelihood of collapsing from the weight of snow or rain buildup.

Shrink wrap serves yet another purpose. That’s preventing moisture from getting in the boat. Humid, warm environments will lead to the growth of mildew and mold, as we’ve said. You might not think mold can develop in the winter, but that’s incorrect. With just a simple layer of shrink wrap, you can keep your pontoon boat mildew and mold-free.


Unless you live in a sunny southern state, then you have to winterize your pontoon boat each year. It’s better to keep it out of the water for the cold season to maintain your boat’s quality (especially the underside).

You also definitely need a cover. Before you apply it, don’t forget to add a layer of shrink wrap to your boat. This reinforces the cover and prevents mildew and mold. With the above information, you’re now ready for whatever winter throws at you.