top of page

Winterizing Your Boat | 19 Tips From The Professionals

Winterizing your boat - 19 tips from the pros

Your Complete Guide to Prepare Your Boat for Winter

As the days get shorter and the temperatures get lower, many boat owners decide it’s time to call it quits on the summer boating season. Although we’d rather be out on the water all year round, the changes in the seasons often dictate that we spend little, if any, time on our boats during the winter months.

However, just because you’re not planning on doing a lot of boating in the winter doesn’t mean that your duties as a boat owner have come to a close. Rather, getting your boat ready to ride out the cold, wet winter season is perhaps one of the most important annual maintenance projects that a boat owner has to take on as improper storage of your vessel in the winter can lead to long term and even irreversible damage to your investment.

That being said, getting your boat ready for winter can sound like an impossible task, especially if you’re not naturally mechanically minded. Thankfully, we’re here to help. Coming up, we’ve got your ultimate guide to winterizing a boat, complete with information on how much it’ll cost you, and a step-by-step instruction manual to getting the job done. Here we go!

Why do you need to winterize a boat?

Why do i need to winterize my boat

First things first: why do you need to winterize a boat? Although boats are designed to handle the harshness of the ocean and the weather when you’re underway, it so happens that letting a boat – or anything with an engine and electronics, for that matter – sit out in the elements for an extended period of time can cause a lot of damage.

Of course, just because winter is coming quickly doesn’t mean you have to stop boating (you can certainly go fishing or on a cruise during the colder months), many people like to call it quits on boating at the end of the summer. Generally speaking, these people tend to leave their boats unused for months at a time, which can wreak havoc on your vessel – and especially on the engine.

In fact, if you don’t winterize your boat, you’re setting yourself up for catastrophe down the line. One of the biggest priorities in winterizing a boat is the engine, which can be seriously damaged from moisture build-up in the fuel tank. When the air gets colder, the moisture in suspension in your boat’s fuel tends to separate out and corrode the aluminum fuel tanks and seams in your vessel.

Once the Spring rolls around, carburetors and fuel injection systems often accumulate particles of aluminum oxide, thanks to this corrosion process, which results in a white sludge build-up and a lot of money for engine repairs. Eek! Plus, as fuel decomposes over time, it can form gross gummy deposits that then harden and increase the corrosion of the steel parts of your engine and fuel pumps.

Of course, your boat’s engine is just half of the story. For example, much like your car battery, your boat’s battery can and will die in cold temperatures. Since we often start-up our boat engine after being at anchor in a remote place for a few hours, the last thing we want is to have a dead battery and no way to get back to the marina. So, taking care of your boat’s battery and electronics is of the utmost importance in the winter.

Beyond the battery, electronics, and engine of your vessel, in the winter, your boat’s gel coat is exposed to harsh elements, such as the cold, wind, snow, and ice, which freeze and thaw to form large cracks in the fiberglass, blisters in the hull, and damage to thru-hull fittings. Simply put, winter can be harsh to your boat, especially if you’re not using it for months at a time. Read about preventing mold and mildew while your boat is not in use.

The best way to avoid all of this potential damage (and save yourself money in the long run) is to properly winterize your boat. If you’re new to boat ownership, this may not be something that you’re used to doing, but with some guidance and practice, you’ll be a pro in no time. Up next, we’ll walk you through the boat winterization process so you can rest assured that you’ve protected your vessel throughout the winter months.

How do I winterize my boat?

As you might expect, winterizing a boat is a process, so don’t expect to get it all done in a few minutes. When you take on the responsibility of owning a boat, you need to be ready to care for it, even when it’s not in use. Of course, you can always pay a professional to winterize your boat for you, but it’s worth understanding the process so you know what you’re paying for. It’s a bit of a lengthy process, so let’s get started!

Winterizing your engine

Winterize Your Boat

So your engine is perhaps the most valuable single component of your boat, so let’s start with getting a boat engine ready for winter. Depending on the type of engine you have (gas inboard/sterndrive, diesel, Genset, or outboard, or PWC), this process will look slightly different in reality, but the concepts are much the same from engine to engine. Here’s what you need to do:

Fill up your fuel tanks completely and add a stabilizer. As we’ve mentioned, moisture equals damage and even death to an engine, so filling up your fuel tanks can help reduce the likelihood that there’s space for moisture to condensate inside the tank and corrode any metal. A stabilizer can help keep any moisture in the fuel in its proper suspended state to better protect your engine and its metal components.

Change the oil and filter. This is good practice for whenever your boat is going to be left in storage for a few months as moisture and acids inside a crankcase can do major damage to your engine

Replace fuel filters. Check your fuel filter for leaks to prevent moisture from getting inside during the winter.

Drain all water from the engine. This process is confusing to many boat owners and varies from engine to engine, though if you get it wrong, you can crack your engine block through the freeze/thaw process. Alternatively, you can use ample amounts of anti-freeze to get the job done.

Check coolant levels. In an inboard engine, there are two cooling systems – the permanent freshwater coolant and the seawater intake. Before you put your boat away for the winter, check to ensure that the permanent freshwater coolant system is clean and up-to-snuff. You’ll also want to close the intake seacock for the seawater intake cooling system, especially if you’re storing your boat in the water. You can also put anti-freeze in the seawater cooling system to keep things happy during the winter.

Fog cylinders in gasoline engines. This process helps prevent moisture build-up within the engine cylinders themselves.

Put your battery on a marine charger. No one likes a dead boat battery, so protect your battery before you put your vessel to bed for the winter.

Winterizing your boat below decks

After you get your engine ready for the winter, it’s time to take care of everything else below decks. Your vessel’s plumbing is particularly susceptible to damage, so you’ll want to pay particular attention to this during the winterization process. Here’s what you need to do:

Pump all the water out of the holding tanks. Water expands when frozen, which can crack your pipes. It’s also worth adding some anti-freeze to the head.

Drain your water heater. Same concept – water expands when it freezes, so protect your water heater by draining it first.

Run anti-freeze through the plumbing and pumps. Check out your boat’s owner’s manual for more specific information as to what you should do.

Drain pooled up water. Your shower sump is particularly vulnerable here, so just make sure you drain out any water that tends to collect in certain spots on your boat.

Remove food. No one likes to start the boating season off by finding a five month old slice of pizza in the fridge. Old food attracts pests, so dispose of it before winterizing your boat.

Air out your lockers. While you’re winterizing your boat, open the lockers up to air them out. This will help prevent mold and mildew growth over time. If you notice a lot of wet equipment in the lockers, dry it out before you close up shop for the winter.