Boat Winterization & Storage

Jon Fesmire |
Winterizing a boat is complicated, and you can find a variety of instructions for doing so in blogs and videos. Here, I have tried to make the winterizing process as straightforward as possible. Always consult your boat manual, since different boats may have different locations for some parts and may require specific steps not mentioned here. Some of the information here won’t apply to all boats. Here are a few of the products you may need:
  • An environmentally friendly, non-toxic antifreeze
  • Fuel stabilizer, marine type
  • Engine oil
  • Outdrive oil
  • A spray fogger
  • A boat winterization kit
You will need to run the inboard engine, but first, remove the propellor for safety, then run the engine to warm it up. This will create the right environment to fully drain the old oil. Also, run cooling water through the engine’s flushing port, which you can generally do with a garden hose. Check the engine for leaks. Attach an intake hose to the water pump and place the other end into your container of non-toxic antifreeze. Run the engine again to circulate the antifreeze through it until the pink liquid starts running out the exhaust port. Next, change your transmission fluid. With these steps done, take out the engine’s spark plugs and spray your fogging oil into their cylinders. Water being a living environment, your boat likely has barnacles or moss growing on the stern drive. Remove these and clean the area with soap and water. The gear case may have experienced leaks, so drain the oil from it and look for moisture. If there is any, repair the seals. If your stern drive has a rubber boot hidden between the transom and the engine,inspect if for cracks. Check all fluid levels, grease all fittings, and consult your manual for specific instructions. Fill the outboard engine tank most of the way with fuel, then treat it with the right amount of fuel stabilizer, 0.5 oz per gallon of fuel. Ice crystals can form in air left in the tank, so a full tank is one with fewer crystals. Definitely check your manual for specific instructions, as they can vary greatly depending on the type of fuel your boat uses. Flush the engine with water. Depending on your outboard engine, you may need to use flush muffs or a flushing port. Remove the cowl and run the engine. Meanwhile, spray fogger into the air intakes. Remove the fuel line from the engine and keep spraying fogger until the engine stops. This will burn extra fuel so you can avoid evaporated residue later. Ice can cause a lot of damage in the winter, so lube the propeller shaft and threads with grease. To finish, change the gear oil, polish the engine interior with wax, then wash and dry the engine exterior. Wash the bilges with hot water, soap, and a brush, then spray with a moisture-resistant lubricant. You can also keep ice away by adding a layer of antifreeze. Larger boats with a drinking water and shower system need to protect the fresh water tanks. Your owner’s manual should be invaluable for doing this properly. First, drain the water heater and water tank. Turn on the cold and hot faucets in the shower and the sinks to drain any excess water. Disconnect the lines to and from the hot water heater to properly isolate it. Per your manual, pump your non-toxic antifreeze into the water lines. Run all faucets again until the pink antifreeze begins to come through. Pour antifreeze into the water heater. The waste removal system on larger boats should be handled separately from the rest of the water system. Go to an approved waste facility and flush the holding tank. While pumping out the waste, pour fresh water into the toilet and flush repeatedly. Clean the system per your manual’s instructions, add fresh water, and pump the tank again. Add antifreeze per your manual’s instructions. This means pumping it through the holding tank and other waste removal system parts, and this may vary from boat to boat. Remove your personal possessions and other valuables from the boat interior. For safety, this includes potential fire hazards and even fire extinguishers. It also includes blankets, chair cushions, and the like. Clean out all containers and drawers. Clean the refrigerator. Your manual may suggest using a dehumidifier to prevent mildew. Ideally, you will be able to store your boat out of water in a climate-controlled boat storage facility. If you can afford to store somewhere on land, make sure your boat is completely clean. To do this, pressure wash the hull and clean off all barnacles and other sea-life that may have attached itself anywhere on the boat. Drain water from the seacocks. Wax the hull. Finally, make sure the batteries are charged, turned off, and disconnected. If you have to keep your boat in the water over the winter, these procedures, always checked against the manual’s recommendations, should keep your boat in the best shape possible. We also recommend getting a professional to do the winterizing, especially if you have never done it before. You may be able to sit in and watch the procedure. We wish you great success in winterizing your boat so you can enjoy it when spring rolls around. StorageFront makes no guarantees or warranties regarding the information contained in this article and is not responsible for any damages. We’re enthusiasts and provide this guide as a starting point. Consult your mechanic for questions.