How to Winterize a Boat: 5 Easy Steps

Winterizing a boat

How to Winterize a Boat: 5 Easy Steps

Too many boats die quietly every winter. Your boat may not be able to come inside and warm up, but if winterized properly it won’t be spending extra time in the repair shop in the spring when it should be out on the water.

A properly stored winterized boat can save its owner thousands of dollars in repair fees and hundreds of hours in the shop. Winterizing your boat (and reading your owner’s manual to learn about specific winterization tips) only takes a day of your time or less but will save you so much time and money in the future. Whether you have an outboard, gas inboard or stern drive engine, here are the 5 easy steps to winterize a boat.

Step 1: The Hull

  • Make sure the hull is free of stress cracks that ice can aggravate.
  • Pop, drain, dry, and patch all gelcoat blisters you find.
  • Pressure wash the outside to clean off any dirt and sea grim. Mix a safe hull-cleaning chemical with some water in a bucket and scrub the hull with a soft sponge. When scrubbed to satisfaction, rinse the hull with fresh water. Make sure to clean your boat in an area where none of the water can contaminate larger bodies of water.

Step 2: The Interior

  • Remove any kind of electronics and electrical systems so they don’t corrode in humid winter weather. Store inside in a dry place.
  • Treat vinyl interiors with protectant gels to prevent drying out and cracking. Check the upholstery and interior for rips and tears that should be treated.
  • Clean and dry built-in head, and drain sinks and showers. Put antifreeze down the drains.

view of boat from the back
Step 3: The Motor

  • Add fuel stabilizer to the gasoline and run for 10-20 minutes to distribute.
  • Fog the carburetor and engine cylinders to prevent corrosion.
  • Change the oil and drain the engine.
  • Flush cooling system and add antifreeze.
  • Spray engine with anti-corrosion spray. Also spray electrical connections with water repellent.

Stabilize your fuel

Fill your fuel tank to about 90% to avoid condensation within the tank (condensation can lead to freezing and expanding that can crack your tank). Treat your boat with a fuel stabilizer when winterizing your boat. Pennzoil Fuel Stabilizer, PRI-G and Stabil are great products that have been known to protect your boat through even the harshest of winters (be sure to read the instructions before use). After adding it to the fuel, run the engine for 10-15 minutes or until you are sure the stabilized fuel circulates throughout the engine.

If you don’t stabilize the fuel, carburetors and fuel injectors can be clogged with varnish deposits. Cost to stabilize your fuel: $5 to $15. Cost if you don’t: $300 to $1,500.

Fog the engine cylinders

First, locate the carburetors in the engine. While the engine is running, spray the fogging oil into the carburetors. You will start to see smoke – this is normal. Spray until your engine stalls, as this is how you know that you are spraying enough. You can also spray the fogging oil into the cylinders. If unsure how to proceed, contact your local marina mechanic.

Each engine manufacturer makes specific products they promote as ideal for their engines, so be sure to find the recommended aerosol for your specific engine. The oil coats the inside of the engine with a thin layer of wax based oil that helps prevent corrosion. If you don’t fog the engine cylinders, corrosion can form inside the engine, covering the cylinders, pistons and rings with a patina of abrasive crud. Cost if you do: $5 – $25. Cost if you don’t: $1,500 – $20,000 (or more).

Drain the engine

Draining the Engine is crucial in winterizing your boat. Locate and open the petcocks underneath the manifolds and on the sides of the engine block. Remove the water-pump hose. Allow pump to drain and dry completely. If you don’t drain the engine, any leftover water can freeze, expand, and crack the engine block and manifolds. Outboard engines self-drain and never require this step. Cost if you do: $0. Cost if you don’t: $5,000 – $25,000.

Change the oil

Put an oil collector under the motor. Unscrew the oil drain plug screw at the bottom of the gear case (do not let the bolt fall into the oil pan and get covered with oil). Unscrew the upper vent plug screw. This will let the oil rapidly flow out of the drain hole. Wait sufficient time (an hour).

If your oil is milky white or grey, consult your mechanic, as there are underlying problems with your motor. While the oil is draining, clean up the drain plug and vent screw, and install new sealing O-rings on the screws. Screw an oil pump adapter into the lower drain hole, and connect the other end of the pump to your oil reservoir. Pump the oil to fill the lower unit of the motor until oil runs out of the vent hole. Screw in the vent plug. Unscrew the oil pump adapter, and quickly screw in the drain plug. Wipe down and clean up any oil spills.

Changing the engine oil helps eliminate moisture, prevent corrosion, and keeps the oil fresh. If you don’t, moisture can cause excessive damage, which can lead to loss of engine power, poor engine fuel economy, and possible engine failure.  Cost if you do: $25 – $100. Cost if you don’t: $500 (excess fuel) – $20,000 (possible engine failure).

Flush the engine

You will need an engine flushing kit and 2 to 5 gallons of antifreeze. Cover the raw water intake with the “ear muffs” and pump the antifreeze through the ear muffs. You want to make sure to get rid of any moisture and pump it thoroughly. Any leftover water can freeze, expand and possibly crack parts of your motor. You want to make sure you do this step very well before finding boat storage near you.

Step 4: The Battery

Charge your battery fully and then disconnect it. Leaving a battery connected will eventually drain the battery, causing you to buy a new one or have to jump start it (which lowers the battery life). An alternative is a trickle-charging unit which slowly charges the battery over a long period of time. The cheaper alternative is to simply unplug the battery and store it in a space with a moderate temperature.

indoor boat storage in a boatel

Step 5: Cover and winter storage

Outdoor boat storage requires finding a boat cover which will protect the waterline. The cover needs to keep water and snow out while still allowing for airflow to minimize mildew growth.

A few good options are polytarp covers (with a frame), polyvinyl (for maximum water repellency), or shrink wrap. While shrink wrapping can be dangerous (and fun as it involves fire, but don’t try this at home), prices can range from $10 (do it yourself) to $100 (top of the line). A normal tarp is relatively affordable. Indoor boat storage does not require a special boat cover.

Park your boat on a flat paved surface if possible to prevent tires from sinking into the ground when the earth heats back up in the spring. If you are having trouble finding storage space in your backyard, driveway or garage, or you are can’t afford to pay the exorbitant prices to keep your boat close to the water or in high-end indoor storage, check out Neighbor boat storage. Neighbor can connect you with both outdoor and indoor boat storage in your own neighborhood for a fraction of the cost of other vehicle storage facilities.

Why Winterize?

With these five steps for how to winterize your boat, you will not end up like Gilligan and his friends (who tragically got off the island, but found their way back again….) Instead, you’ll enjoy your watercraft for many years to come. Winterizing and storing your boat correctly is a small price to pay to preserve and maintain your memory-making machine.

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