Winterizing A Boat: How to Store a Boat in Winter

It’s that time of the year again when the days are shorter, nights are getting longer, you start experiencing cooler temperatures, and you can see colorful changes in the trees all this signaling winter is just around the corner, sadly marking the end of the boating season. It's time to think of winter storage for your boat.


Marina Storage

Winter Boat Storage Essentials

Now that the boating season is winding down you need to prepare the boat for storage for the coming winter. At its most basic, winterizing a boat simply means clearing out any water aboard or applying the recommended antifreeze product to protect it against the lowest temperatures.

Did you know that when fresh water freezes it expands in volume by about 9% and this expansion usually yields a significant force which is tremendous enough to burst pipes, crack an engine block, split hoses, brake exhaust manifolds, damage the fiberglass and even destroy the refrigeration system in a day.

You don’t want to be among the three-quarters of boaters filing up claims to the insurance company at the beginning of spring simply because they didn't prepare their boats for hibernation and winter's icy grip has clutched their masterpiece craft.

The majority of boaters who don’t winterize or fail to winterize properly usually risk expensive repairs and moreover repairing process tends to be time-consuming considering the boat doctor is at his busiest time.

To avoid all the inconveniences that you might face at the beginning of the boating season due to lack of proper maintenance or neglect here is a checklist on how to winterize a boat.


  • Clean out the interior
  • Clean off the exterior
  • Use the right winter cover
  • Winterizing water systems
  • Check sanitation and Air Conditioning systems
  • Check stern drive, outboards engine and inboard engine
  • Take care of fuel systems

Clean Out The Interior

Among the things that must be done when winterizing a boat is to clean the interior of the boat.

Moisture usually is a getaway to mildew, mold, and corrosion which will definitely make your boat during spring look like a science project.

You need to organize and thoroughly clean the storage compartments, cabinets, sideboards and any other area which might have gotten dirty during the boating season.

You also need to remove equipment’s such as accessories, non-factory installed electronic equipment’s, fishing equipment’s, flotation devices, safety equipment’s any ladders on board and basically anything that’s not bolted down.

Leaving these equipment’s on board will only attract some mildew.

Work on your cushions and floor by removing all the dust and dirt that might have piled up.

This will significantly minimize the chances of mildew and mold growing in the interior of the boat and also makes your boat uninhabitable place to call home for rodents.

You can use some mildew sprays to keep the mildew at bay some dehumidifier to keep your boat dry, and mouse traps or poison to keep rodents away. Remember also any built-in units such as showers and sinks should be drained and sprayed with some antifreeze.

Clean Off The Exterior

Boat winterization also involves taking care of the boat exterior. When you pull out a boat out of the water you need to check for mussels or other water-based plants which might be attached to your boat and remove them.

Take some warm water and a good environmentally friendly marine detergent clean your hull and scrub it well just to clean off any excess oil, lubrication or grease which might have spilled over during the winterization process.

This reduces the chances of your boat rusting and causing some permanent damages to your boat’s exterior finishes.

Use The Right Winter Cover

Regardless where your boat is, either in or out of the water there is no alternative but covering your boat is mandatory.

A cover has many benefits among them includes protection from UV rays, keeps debris and leaves from clogging scuppers, protects the deck and the cockpit from the pool of water and generally from the snow and ice.

There are three cover types out there that’s the plastic tarps, canvas tarps, and fitted covers. Among the three the most recommended is custom made canvas. You can either decide to cover the boat yourself, hire a professional or hire a shrink-wrap pro.

Winterizing Water Systems

Many folks usually assume draining their faucet, wash-down nozzles, showerheads or other fresh or raw water systems onboard merely is enough, but that’s not the case. You will have to run antifreeze through the system which will guarantee you that no water will freeze in the system.

It’s also worth noting that the right kind of antifreeze you are looking for is propylene glycol and not the automotive or engine coolant made with ethylene glycol which is deadly

Sanitation And Air Conditioning Systems

Among the most critical steps in winterizing a boat, it’s winterizing the marine sanitation system. In this case, you need to run down fresh water severally in the system to remove any residue and also to empty your holding tank.

The same propylene glycol antifreeze applied on the freshwater system should be employed in the sanitation system all the way to the holding tank. You can also check the manufacturer’s recommendations just in case you have other waste treatment devices on board.

There several methods applicable in winterizing an air conditioner but pumping propylene glycol antifreeze through the entire air conditioning system is good enough to see you through the winter.

You can repeat the procedure if your boat has more than one air conditioning unit.

Winterize Your Stern Drive, Outboards Engine And Inboard Engine

The process of winterizing a boat engine varies depending on what type of an engine a boat has which might be a stern drive, an inboard, an outboard or a jet should consult the manufactures manual specifics on how to winterize a boat.

However regardless of what type of engine your boat is using there three essential winterizing steps applicable to all.

  1. Changing the oil and replacing the oil filter
  2. Changing the fuel filters or the fuel filter canisters and adding a stabilizer to the fuel.
  3. Draining water from the engine and using antifreeze which is a process that varies depending on the engine.

Fuel Systems

Regardless of the fuel, your boat is using whether its gasoline which has ethanol-blended fuel or diesel fuel, water is the number one enemy to your fuel supply.

For years it has always been a custom to fill the tanks with at least 95 percent which would limit the amount of air in the tank thereby reducing moisture through condensation.

However, this trend is not advisable anymore due to the nature of ethanol and filling up to the brim might bring more harm. Experts recommend when winterizing your boat fuel tank just fill it with low fuel and when spring kicks off start off with fresh stuff.

Remember, and this is essential always to remember that adding an appropriate fuel stabilizer is a must do an activity


Now that I have listed down a few tips for winter boat storage and you have some know-how on how to winterize your boat, I will just recommend that you store your boat indoors where there is a climate controlled facility although this option is hardly an option.

Don’t leave it in the water you would rather store it offshore since this reduces the chances of damages.