How To Winterize Your Boat

Boats properly stored ashore and winterized are most likely to hit the water without damage and be ready for on-the-water fun come spring.

winterize your boat and prepare it for winter storage
winterize your boat

Before temperatures drop below freezing, you must prepare your boat for the coming winter. In simple words, winterizing means draining any leftover water on the boat or replacing it with antifreeze to protect it against very low temperatures. We also have an article on dewinterizing.

In this article, we take a comprehensive look at how to winterize your boat, thus preventing it from damage and unexpected accidents. Our expertise with boats enables us to give you the best advice so you can be fully prepared for the winter.

Why Should You Winterize Your Boat?

If you live in a cold climate, you need to winterize your boat. Failing to do so can cost you time and money. The volume of freshwater expands by approximately 9% when it freezes and can push outward with a very strong force. This expansion can cause damage to the engine, split hoses, crack fiberglass, or destroy a refrigeration system. Not surprisingly, recovering from this damage can be time-consuming and costly.

By the time your boat has undergone repairs and is back in its working condition, a good chunk of the boating season will have passed. Most boats take an hour to a day to winterize, so it is highly recommended that you take adequate measures before winter begins.

At what temperature should you winterize your boat?

As a general rule, you should winterize your boat before the temperatures drop below 25 degrees Fahrenheit or around -3 degrees Celsius. To stay safe, you should begin winterizing before temperatures drop below freezing point (35 degrees F or 0 degrees C).

Do you have to winterize a boat if you use it?

It is crucial to remember that once you winterize your boat, you will not be able to use it again, even if the weather gets warmer after a couple of weeks. So, if you use your boat regularly, you should wait until it’s the right time to winterize it.

The only exception is if you decide to keep your boat in the water, you can still use it when the weather gets warmer.

What does winterizing a boat consist of?           

Winterizing a boat normally includes winterizing systems such as the faucets, water holding tank, and showers; replacing engine oil to get rid of any moisture; stabilizing fuel; protecting internal engine components against harsh winter elements that can result in metal-to-metal contact and corrosion; and lubricating engine fittings to protect them against oxidation, corrosion, and rust.

Boat winterizing kit | Can I winterize my boat myself?

You can winterize your boat yourself, provided you have the right tools and information. Before you get started, contact your boat manufacturer or check the owner’s manual for more precise instructions. You should also consider investing in a winterizing kit , a compact supply of all the necessary tools that you will need to winterize a boat by yourself.

The following guide provides step-by-step instructions to seamlessly winterize your boat before the upcoming winter.

How do you winterize a boat step by step

Whether your vessel has a gas inboard, outboard, or stern drive engine, below is a step-by-step guide that will ensure easy and quick startups when warm weather sets in.

Change the Engine Oil

Acids and moisture in old oil will collect in engine parts while in storage, so you must properly drain it. First, you should warm up the engine while the boat is still in the water, so more contaminated oil will drain out, and the impurities can get flushed easily.

Winterize your yacht engine 

You can winterize your yacht engine by flushing it with fresh water, draining the old oil, and replacing it with manufacturer-recommended oil. Next, change the transmission fluid, remove the spark plugs, and add motor oil inside the cylinders. Lastly, fill the cooling system with antifreeze, then cover the yacht properly to prevent moisture flow.

Incorporate a Fuel Stabilizer 

Fuel quality deteriorates in only 2 months, causing varnish and gum to collect in your engine. This can lead to hard starting, reduced engine life span, and poor performance. The best way to circumvent these issues is by incorporating a fuel stabilizer.

After adding the fuel stabilizer, fill the tank with new fuel to prevent corrosion-inducing water condensation. Let the engine run for a couple of minutes to warm it up – you can do this either while your boat is in water or when using a fitting made to run the engine with a watering hose.

boat winterizing
boat winterizing

Remember that draining gasoline isn’t enough to prevent varnish from forming in engines since some fuel is always left behind. This is why you need to add a fuel stabilizer to help stop the fuel from deteriorating.

Flush and Drain Cool Water 

Drain the water completely from your engine to prevent damage when frozen water expands. For sterndrive and inboard engines, flush them with clean water with the help of water muffs to connect a garden hose to your cooling system. Never make the mistake of running a water engine without water. Next, flush the liquid until the engine reaches its optimum operating temperature.

The next step is to remove the drain plugs, normally located in the engine manifold and block. You may also need to drain leftover water by removing the water pump hose.

Protect Internal Engine Parts 

While sitting in storage, engine oil can drain away. This exposes internal engine parts to harsh winter elements, leading to cylinder scuffing and corrosion. To avoid these problems, use a fogging oil spray that will penetrate deep into the engine and add a protective coating of an anti-corrosive compound.

Replace your Gear Oil 

Your engine is not the only part of your boat that requires an oil change while winterizing it. Your gear oil also needs to be replaced. Simply drain the old oil from the compartment and add a fresh supply. The new gear oil will help protect your transmission from corrosion and moisture.

Clean the Boat Properly

Once you’ve taken care of the engine and its parts, the next step to winterize your boat involves its looks. You need to do a thorough cleaning before you can store it for the wintertime. Any stains or dirt will worsen if left idle for several weeks or months. Inspect and clean everything, from the trim to the seats and flooring.

If the hull of your boat has barnacles or other forms of marine growth due to sitting in water for months, take the time to wash it down. Once you are done, add a fresh coat of wax to provide it with an extra layer of protection.

Cover and Store the Boat Carefully 

Winterizing your boat is incomplete until you properly and carefully cover it for the upcoming winter season. Invest in a high-quality, durable, rugged boat cover to withstand harsh weather conditions. Be sure to store your vessel somewhere free from any moisture or precipitation exposure.

How much gas should I leave in my boat over winter?

Fuel experts recommend storing the fuel tank at 90% of its capacity during winter. This will minimize the probability of condensation and leave room for expansion due to the cold. This criterion applies to all compositions, sizes, and shapes of fuel tanks.

The science behind this is as follows: Less surface area exposed inside the tank and a smaller air volume minimizes the probability of condensation in today’s water-absorbing fuels. Besides filling the gas tank almost full, make sure to add a fuel stabilizer before storing the boat.

Alternatives to winterizing a boat

  • Insulate the boat: Insulation reduces the amount of internal condensation and keeps the boat warmer and dryer during winter. Materials best suited for insulating boats include spraying urethane foam, cork, and dry-cell foam.
  • Sell your boat
  • Shrink-wrap your boat to protect it against mildew and moisture.
  • Remove batteries and place them on trickle chargers.
  • Get a heater: A good heater can quickly warm the cabins since they are relatively small on boats. Opt for oil-filled radiant heaters since they are safer, and avoid space electrical heaters. An array of heaters is available to keep your boat warm during the winter storage season. Whatever heater you choose, ensure it is engineered and certified for boat use.
  • Winterize sea doo jet ski: To winterize a Sea Doo jetski, first clear out all the storage compartments. Next, drain the water by running the engine in short bursts until no more water is coming out. Use the manufacturer’s instructions to flush out the system, as this will remove any silt, algae, and other debris. Add antifreeze to the cooling system of the jetski, lubricate the seals and cables, and then add a stabilizer to the fuel to prevent it from deteriorating. Lastly, remove the battery, thoroughly cover your jet ski, and store it in a safe 


In this article, we comprehensively discussed the winterization process for your boat before the upcoming winter season. If you do not want to spend so much time winterizing your boat, you can also use some quick alternatives to keep the boat damage-free while in storage.

#WinterizeYourBoat #WinterizeYourYacht #WinterizeYourJetski

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Infographic: how to winterize your boat
Infographic: how to winterize your boat

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