As leaves fall from the trees and waters freeze, it is time to acknowledge that boating season is over.

Whether your boat is small or large, you will need to begin figuring out the many steps to wintering a boat. It will be easy to become a little overwhelmed when you realize winterization is not so easy as simply finding a spot to store your boat.

Remember: Even if it is tempting to skip a step, the small cost of completing this process will save you hundreds later.

Winter can be tough on a boat if it is not prepared correctly. A step that seems tedious and costs $15 now can become a monster problem that costs anywhere from $2,500 to $15,000.

But don’t fret.

If this seems hard, you are in the right place.

In this article, you will find all the information you need when it comes to knowing how to winterize a boat. This way, the maintenance it needs in the spring would come off minimal and at a low cost.

Start Your (Boat) Engines!

With all boats, you will need to use fogging oil on your engine. You can spray fogging oil into the engine’s air intake while the boat runs or you can use it to coat other parts of the engine while it is off. Also be sure to change the engine oil because old oil can result in some nasty repair bills.

Inboard Engines

Other processes to winterize a boat engine depend on the type of engine your boat has.

An inboard engine is easily damaged by water remnants inside the engine. Any water that is still in your inboard engine will freeze, sometimes inside the engine’s cooling passages, leading to very costly repairs.

Find an antifreeze made with propylene glycol, and be sure to check the antifreeze is rated okay for engine use.

Remove the raw-water intake hose and place it in a bucket full of antifreeze. Run the antifreeze through your engine until it has run through the engine’s cooling passages. By doing this, you are protecting your inboard boat’s engine from cracking in the cold of winter – and saving yourself a repair bill of $5,000 to $20,000.

Outboard Engines

The use of antifreeze is necessary for inboards only. However, when it comes to winterizing a boat, that includes winterizing outboard engines too.

Outboard boat engines are self-draining, so they do not require the same draining process as inboard engines. You will still need to flush the engine, but you can use fresh water instead of antifreeze.

Outboard engines are meant to drain fully when tilted down, leading to a smaller chance of cracks from freezing.

The most important step to winterize an outboard engine is to change the lower-unit oil. Your gear lube can have a lot of damage in spring if you don’t remove any leftover water from the lower unit. You must also change the oil and filter of the engine for an outboard engine boat.

Stabilize Your Fuel Tank

Depending on the type of fuel you use on your boat, the process to winter the boat will be slightly different. You may want to check with a professional on their recommendation since there is some difference in opinion on the safest way to prepare your boat.

The traditional advice given is to always keep your tank full in winter to avoid allowing extra air moisture to freeze. If you follow this traditional advice, try to fill your tank to at least 95%. With ethanol in gas, some experts now recommend removing as much gas as possible from your tank and then treat the remaining gas.

Regardless of whether you decide to fill your tank or drain it, make sure you treat the gas that remains in the fuel tank. Add a fuel stabilizer to again reduce those post-winter maintenance bills.

You’re Almost Ready for Winter

With just a few final steps, your boat is all ready for winter.

Remove your boat’s battery. Charge it if it is necessary, and then place it in a cool, dry place for winter. Check it occasionally to make sure it remains charged and in working order.

Next, make sure you take the time to scrub down your boat from the inside out. You don’t want to leave a bunch of mess or dirt over the winter or cleaning in the spring will be much worse than you expect.

Hopefully, you’ve already decided where and how you will store your boat. Whether you have inside or outdoor storage lined up, keep in mind that you will want your storage to be airtight. By doing so, you prevent bacterial growth and any pests that could find their way inside.


After these final steps, you have a fully winterized boat.

Rest easy through winter knowing you’ve done all you can to protect your boat from the winter elements.


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