As avid boaters we all fear the onset of yet another bitter winter. This is a sad time for us all as it marks the end of the long lounging days on the water and the arrival of driving snow and icy roads. But how do you winterize a pontoon boat?

Winterizing a pontoon boat is a simple process which can be broken down into an easy to manage list of to do items. Winterization simple steps include cleaning the boat, removing loose equipment, treating the engine and fuel tank and finally covering the boat to keep the snow out.

Why you should winterize your pontoon boat?

As necessary as all the usual preparations for winter are, winterizing your prized pontoon boat should be near the top of your to do list.

However, this task can often be daunting to the un-initiated and if not done properly can result in a lot of wasted time as well as a damaged boat come spring time.

how to winterize a pontoon boat

If the duck’s on ice, you should have already winterised your pontoon boat

On top of all that if you’ve taken the time to read the fine print on your boat insurance, it is likely that you came across a section where lack of proper maintenance can void any insurance claims.

Not winterizing your pontoon boat can be seen as deliberate negligence and as such any resulting damages will not be covered. So, don’t take the risk.

In this guide I will take you step by step through the proper procedures to winterize your pontoon boat in the most efficient way and will remove all the guess work and fear from the equation.

Winterizing your pontoon boat

The following section will go into more detail for each of the steps required to properly winterize your pontoon boat to ensure that when you take the boat out in the spring there are no unwanted surprises and you can hit the water in no time.

1. General pontoon winterization tasks


Cleaning and polishing the outside of the boat is a lot easier before winter. If you leave it until the spring rolls around, any stains, dirt or barnacles will be much harder to remove after they are given time to sit.

The inside of the boat should also be cleaned for the same reason, however after cleaning make sure the inside is completely dry before closing up for the winter as wood and carpets can breed mold.

Equipment removal

Any loose equipment such as flotation devices, fishing equipment, electronics or entertainment equipment should be removed from the boat to keep them safe from the cold as well as from theft or vandalism.

There’s also the other risk in winter, where rats, mice, birds, and an assorted bunch of pests will seek refuge in your pontoon. If you remove the valuables, and any traces of food, you can reduce the risk of damage.

Drain water lines

If your boat has plumbing onboard such as toilets or drinking water lines, these should all be drained.

If this is not done the water will freeze in the lines resulting in burst pipes and damaged plumbing.

2. Engine & fuel tank treatment

Engine winterization

If your engine has been sitting idle for any extended period of time it is almost a certainty that corrosion will have begun to set in. This is even more critical in areas that undergo large temperature fluctuations.

When an engine is not operating for extended periods of time, the oil and lubricants within the engine slowly run down critical internal surfaces of the engine and pool at the lowest points. Then as the temperature and humidity fluctuates there is a good chance that water vapor will form on these internal surfaces and corrosion will take its natural course.

This corrosion can very easily bind up critical components and render your engine useless.

You can prevent this from happening by using a decent fogging oil (view my Amazon recommendation).

What it does itcoat all the internal surfaces with long lasting lubricant that is designed to stay in place during long periods of no use. Fogging oil comes in an aerosol can and is generally applied as follows:

  1. Start the engine, and whilst running remove the air filter and spray the fogging oil into the air intake of each of the cylinders.
  2. Shut the engine off after 10 seconds.
  3. Remove spark plugs and spray the fogging oil into the cylinders. The aerosol can should come with a long tube to assist with this. Replace the sparkplugs once done.
  4. Change oil filters.
  5. Drain any coolant from the engines and replace with a propylene glycol-based antifreeze. Ethylene glycol anti-freeze is not recommended. I recommend Star Brite (a name you should be familiar with!) – here’s their anti-freeze on Amazon.

It must be noted that various types of fogging oil have different application instructions and thus the instructions must be read carefully. Also take the time to read through the engine’s owner manual.

PS: You can see a photo of the anti-freeze I use in my pontoon boat here. Click that to see the latest prices.

Fuel tank winterization

As in the case of the engine, the changes in temperature and humidity can result in condensation forming inside your fuel tank.

This can create a range of issues if not properly handled. Some of those are listed below:

  • Corrosion – This is the most obvious, as water collect on the inside of the tank, corrosion will begin to take place. This can be catastrophic for a fuel tank as they are often made of this sheet material that will corrode through very quickly
  • Fuel degradation – If you use ethanol-based fuel, it undergoes phase separation over long periods of time if exposed to moisture. This separation results in a deposit of an ethanol/water sludge on the bottom of the tank and gasoline at the top.

Due to these concerns there are some recommended steps to follow to eliminate risk to your fuel tank.

  1. Fill the tank up to ¾ full. This leaves little space for the formation and collection of moisture.
  2. If the fuel contains ethanol, a stabilizing agent must be added to the fuel. It is also a good idea to add a stabilizing agent even if the fuel does not contain ethanol as gasoline can also degrade over time.
  3. Change the fuel filters.

Battery winterization

If you plan on storing your pontoon boat out of the water, then it will be a good idea to remove the battery from the boat and keep it stored in a cool and dry place.

Charging the battery periodically will insure it remains in good working order come spring time.

If the boat is to be stored in the water, don’t remove the battery and ensure that it remains charged. This is in case the bilge pump needs to be used in a hurry.

3. Covering the Boat

Once all of the other steps have been completed, the final step is to cover the pontoon boat. There are two methods of covering your boat.

One is with heat wrapping and shrinking, the other is with a pre-bought cover.

Handy Hint: Before you cover your pontoon boat for the winter, take steps to prevent any pests or critters getting into your pontoon over the winter months. Here’s a guide on pest prevention I wrote.

Method 1: Shrink-wrapping the pontoon boat

Stow the Bimini top

The Bimini must be removed as more often than not this structure is not designed to handle the weight of snow and will get damaged if used as a support for tarp or shrink wrap.

It can also be lowered down and kept on the boat if this is more convenient.

Build the frame

The frame must be built in such a way as to ensure it can support any snow that might accumulate on top of it, measure the highest point on your pontoon boat and add around 18 inches to that.

This will give you the required height of the support posts. Install your straps by securing them to the top of your support posts and tying them onto the railings. The more straps the better the weight distribution, just do not overdo it.

Open up a vent on the shrink wrap, these vents can be bough at any boating shop.

The straps are secured in such a way as to create a tent form with slopped sides to let any snow buildup slide off the side.

Wrap the boat

Place shrink wrap material over the boat so that it covers the entire area. Cut off any excess. Secure the sides of the wrap to the boat using another strap and tighten it. Fold the bottom of the shrink wrap around the strap and weld the shrink wrap so that is encloses the strap.

The rest of the wrap can now be heated.

Be careful not to burn though the wrapping. A detailed breakdown of this process can be found in the video below and you can also read this quick guide to shrink-wrapping a pontoon boat with pictures.

Method 2: Use a decent boat cover

If all this sounds like too much hassle, then you can always purchase a custom-made cover for your boat.

These can be reused for many years and are specifically designed to withstand the rigors of winter.

Elsewhere on Pontoonopedia you can find various guides to what the best covers are; here are three examples if you need any guidance on what to buy:

4. Keeping your boat and trailer secure

Where you keep your pontoon boat stored over the winter is a massive consideration, and one which you should not take lightly.

Thieves will often steal boats to order and can make off with trailers in minutes before you even realize it’s happening.

I have developed a guide to keeping a boat and trailer safe from thieves. It includes lot of ways in which you can make criminals have to work a lot of harder if they are going to steal your boat.

It includes tips on hitch locks, sensors, GPS tracking devices, and even how you park your trailer to make it harder to be towed away.

How much does it cost to winterize a pontoon boat?

So, how cost-effective is it to winterize a pontoon boat yourself?

First of all, having a boat winterized professionally can cost anything from $200 all the way to $600. But it all depends on the size of your pontoon boat and the area you live in.

Winterizing a pontoon boat yourself can definitely save you money and time. The main cost element is the covering for the boat whether it is shrink-wrapped or a pre-bought cover.

Then you need to consider some auxiliaries like extra fuel, antifreeze and fogging oil. This can bring the cost to around $130.

How to de-winterize a pontoon boat

And what about when it comes to de-winterizing your pontoon boat as the winter period comes to an end? People don’t often talk about it, but it can be just as important.

It can be time-consuming, but the process of de-winterization is just as essential as the winterization before the cold weather hits.

pontoon boat de-winterization

Spring is coming. It’s time to de-winterize your pontoon boat!

If you do it right, and do it well, you will get much more from your pontoon boat and reduce the chances of expensive maintenance bills.

I’ve split the pontoon boat de-winterization process into 6 simple to follow steps.

1. Check your boat battery

Boat batteries have a lifespan of around 5 years. After that, they will need replacing. However, you can take better care of it to increase the longevity of life, particularly during the de-winterization stage.

Once you have un-covered your pontoon boat, re-fill the battery with water (fresh and distilled). Then you need to check the charge with a battery tester.

If your battery still has good charge, then it’s fine. If not, you might need to replace it.

If the battery has a strong charge, take the wires off the charge post. Then give them a really good clean up as they might have corrosion on them. I use a small wire brush for this.

Once the wires have been cleaned up and look new, cost the charge posts with a lithium grease. This will protect the charge posts and make them last longer.

Handy Hint: If you do have to buy a replacement battery, read this guide to pontoon batteries.

2. Test your boat and marine electronics

Now you need to check all your electric components including any switches. Move from one to the next, tuning things on, and seeing if they are still active.

I’ve seen examples where mice have got into pontoon boats over the winter, even with shrink-wrapping, and have chewed through wires, or damp has got into the systems.

3. Change your engine oil and fluids

The engine is going to be the biggest and most important aspect when de-winterizing your pontoon boat. Check it, check it, and check again.

The first thing to do is take a look at the oil levels. Are they as they should be?

If you changed the oil during the pontoon boat winterization phase, then you won’t need to change it again. But if you didn’t, now is a good time to do so.

Also check the oil in the outdrive as well, perhaps topping it up or changing it completely if required.

Other fluids and check to be made on the engine include:

  • Engine coolant fluid and level checks
  • Power steering fluid and level checks
  • Look for any signs of visible leaks underneath the engine area
  • Look for cracks or leaks underneath the engine or in cables and fuel lines

And one fluid aspect that will need a lot of attention is the cooling system.

If you already flushed it through when winterizing your pontoon boat, it’s now time to top it back up. Use a 50/50 mix of anti-freeze and water.

And as with the engine, check all around for any visible signs of wear and tear including cracks and corrosion.

4. Inspect the gas tank and fuel lines

If you left no fuel in your tank over the winter, water and moisture might have settled inside it. As you can imagine, that’s a sure-fire for rust could develop in the gas tank and fuel lines.

Fuel lines in particular can become cracked and damaged when they get really cold in the winter.

Take a look at them and see what the state of play is, replacing them if necessary.

5. Check your engine and motor belts for damage

During the winter off-season, connecting belts can become worn, so give them a visual once over, and run your hands up and down them to check for any wear and tear.

You should also apply pressure to them to see if any slack has developed in them whilst in winter storage.

If there is any debris and black dust around them, that’s a sign they will need replacing.

6. Check your safety equipment and gear

The safety of you, your passengers, and other boaters is the most important aspect of pontoon ownership.

Check that all your PFDs, life jackets, safety lines, kill cords, fire extinguishers, and anything else related to safety is in good working order and hasn’t expired.

Also test all lights on your pontoon boat, including any navigational aids, horns, flares, and whistles.

The last word…

Knowing how to winterize a pontoon boat (and then de-winterize it before the season starts) is an essential part of ownership.

Pontoon boats will depreciate in value, you can’t stop that, but with a prescribed and efficient winterization process you can help to keep value up and repair or maintenance costs down.