How to Winterize Your Boat

How to Winterize Your Boat

Whether you like it or not, Summer is over.

The boating season has come to a close.

Our crews are nearing the end of the removal season also. That’s a sure sign that the season has ended.

Here are tips to winterize your boat and prevent significant problems in Spring.

Can you really do it yourself?

If your boat needs significant maintenance, now might be the time to have the work done. Some service providers offer preventative maintenance as part of their winterization work. 

Why not schedule it now? You’re not using the boat anyway! You’ll get out on the water quicker in Spring. It’s better than if you try to get the work done in the spring when shops are busy.

Winterizing your boat by hiring a professional is always a great idea, but it can be an expensive one.

However, if you take it slow, and maybe enlist the assistance of a boating buddy or a willing teenager, you shouldn’t have a problem- (willing means a bribable teenager.)

You know your boat better than anyone. Use your best judgment about your boat needs. You could also refer to your boat owner’s manual. Sorry guys – some people actually do read those.

For example, are alcohol-based types of antifreeze okay to use on your boat? Your manual can answer that question.

What do I need to Winterize my Boat?

Start by making time to work on your boat.  

Next, make sure you have the necessary items to get everything done. (Here’s where reading your manual comes in, guys). You’ll need products like antifreeze, fuel stabilizer, and fogging oil.

Here are some of the top products you’ll need to complete the winterization job.

  •  Fuel Stabilizer — Gasoline decomposes over time. Deposits form over time in your fuel tank. A fuel stabilizer, such as STA-BIL, keeps the fuel fresh and prevents buildup while stored over the winter. Using this, you won’t have to drain the fuel tank, and your boat will start up nice and easy in the spring. Don’t be afraid to add extra stabilizers.
  • Marine Antifreeze — Like the water in your car engine, antifreeze is required to protect your boat’s engine and other components. Unlike a car, you want to use only a marine antifreeze.

Why Use Marine Antifreeze?

Boats have a circulation system that uses water from the lake. It pumps the water through the engine block before discharging it back into the lake. 

Automotive antifreeze is very toxic and should never be returned to the lake. Protect both the marine system and the environment. 

As an alternative, RV antifreeze tends to have similar properties and can be a good choice.

Choose an antifreeze made with propylene glycol because it’s non-toxic and biodegradable.

What else should I have available?

  • Fogging Oil — There are many steel and iron parts in a boat motor. Fogging oil lubricates these internal parts and repels moisture to prevent rust. Follow the directions on the container.
  • Marine Vinyl Protectant — Cold weather can dry out vinyl deck seats and chairs quicker than you might think. Meguiar’s Marine/RV Vinyl and Rubber Cleaner (Amazon) will keep your vinyl deck furniture from drying out and cracking over the winter.
  • Marine Lubricant — Look into a product like Overton’s Marine Penetrating Lubricant to stop rust and repel moisture.

How to Winterize Boat Motors

Now to the actual winterizing.

The motor is the single most important and most expensive part of your boat. Outboard motors easily run over $10,000.

You want to ensure the motor was winterized to eliminate the need for repairs or purchase a new engine, both of which are extremely expensive.

While the general concept is the same, there are a few differences in winterizing inboard, outboard, and I/O (sterndrive) motors. Don’t forget about those jet-skis.

How to Winterize Outboard Motors

  • Add a fuel stabilizer, like Sta-Bil,  to the gas tank to prevent the valves and motor from “gumming up.” No one wants to hear an engine turning over repeatedly with no sign of life.
  • Flush the water tank with fresh water. Then drain the tank.
  • Flush the motor with marine antifreeze and fog the engine with fogging oil.
  • Be sure to store the engine in the vertical position, so if any water remains, or somehow gets inside over the winter, it will drain away.
  • Lubricate grease fittings.
  • Remove the propeller and grease the prop shaft. 

Winterizing an Inboard or I/O (Sterndrive) Motors

Inboard and inboard/outboard (a.k.a. sterndrive) motors require the same primary winterizing process. 

Proper winterization is crucial for this type of engine to prevent the water from freezing and cracking the block.

  • Put STA-BIL in the fuel tank.
  • Start the engine and get it up to temperature.
  • Flush with marine antifreeze and fog with fogging oil.
  • Change the oil and the filter.
  • Remove water drain plugs in the exhaust manifold and the engine block if available for extra protection.
  • If there are no plugs on the block or exhaust, remove the thermostat to flush with antifreeze. Replace the thermostat when done.

Winterizing Jet ski Motors

Did you think we forgot? While they don’t have a propeller or a traditional motor, jet-skis and jet boats still require winterization. 

  • Put STA-BIL in the gas tank and fill the tank.
  • Flush with marine antifreeze. You’ll need a pump, as jet-driven engines don’t have a water pump of their own.
  • Change the oil if it’s a four-stroke.
  • Fog the engine.
  • Take out the battery and store it inside over the winter.

Winterize the Fuel Tank of the Boat

Gasoline contains a small amount of water. Therefore, it’s vital to winterize the fuel tank. Even a tiny amount of water can freeze and cause damage to your boat’s fuel tank.

Even if it doesn’t freeze, the water will sink to the bottom of the tank and sit there waiting to run through the engine in Spring.

There’s a debate on whether it’s best to fill the tank to the top or leave it empty. If you use a good fuel stabilizer, it should be sufficient to leave gas in your tank.

  • Change fuel filters.
  • Fill with fuel and add a fuel stabilizer like STA-BIL.
  • Change the water separators, if equipped.

  Did you Winterize the Bilge of your Boat?

Here are a few winterizing tips:

  • Clean the bilge with soap and water.
  • Spray with a moisture-displacing lubricant.
  • Use antifreeze to prevent water from freezing. (Remember our tip above)

Winterizing the Cover and Accessories of a Boat

Boat covers need a little love too. One storm could pull the cover right off your boat, or, at the very least, rip and tear it.

To avoid this, make sure that it’s intact and robust enough to withstand strong winds. Choose a heavy canvas cover that’s water-resistant and large enough to cover the waterline of the boat.

A better option is shrink wrapping. Shrinkwrapping, customarily done at a marina or boat storage yard, is the better choice but can get expensive. 

Here are a few tips for the traditional canvas cover:

  • Use insect and rodent repellent to steer clear of spiders, bees, mice, and other troublesome creatures. You don’t want to pull that cover off next spring and find a swarm of bees. 
  • Secure padding on sharp corners, such as around windshields, to prevent wearing through the cover.
  • Make sure that there are no “dips” in the cover where rain or snow can accumulate.
  • While you’re on deck, give the vinyl chairs and seats a good going over with vinyl cleaner. Remove cushions over the winter.

It may seem like a lot of work to get your boat ready for winter, but the time and care you take now will ensure that it stays cold-weather safe and prepared to go in the spring.