Tips on How to Winterize Your Boat

It comes to that time of the year when we have to deflate the watersports tubes, roll up the ski ropes, reassemble the bimini top and think about getting our boat ready for the long winter. Well this is the case in many parts of the country, unless you live in Florida or Southern California, of course. Getting your boat ready for the winter is much more than putting antifreeze in your engine and calling it good. There are lots of other things that should, and need to be done, to ensure you boat is in tip-top shape come spring time. These things can also save you time and money when it comes to getting ready for the new emerging boating season.

This article is to help provide tips on getting your boat ready for the winter without breaking the bank. It is broken down into sections, and by all means, skip the parts that do not pertain to your type of boat. From a fishing boat up to a large Motor Yacht, each boat has to be winterized if you are in a climate that will get to the freezing mark. Some boats have more systems and require much more work than others.

I will preface this article by saying, this is not the last word on winterization and each model can have different systems that need to be serviced, so by all means consult your owner’s manual to ensure you have completed all the necessary tasks. I find it easiest to make a checklist of all the things required to winterize previous to starting to ensure nothing is missed. Also create a list of items it will take to do the job like Antifreeze, drive lube, charcoal and what not. Of course having somebody help you that has experienced this before would be a nice bonus.

Engine & Drive: I like to start with the engine and drive systems first. That is typically the hardest to get to and the deepest in the boat. From there I can work out to the extremities of the boat. Remember that some of the items I explain here can done in spring, but doing them now will save you time in the spring and help keep your boat in top shape.

Outboard Type Engines:Start by flushing the engine with fresh water using muffs and attach it to the area where the water gets picked up. This is typically on the lower unit of the engine. Start the engine and let it run, with the water connected of course, until the water coming out is clear. Stop the engine, disconnect the fuel line and restart the engine with the water still connected. Run the engine until it stops.  This will prevent build up of deposits and tarnish in the carburetor and fuel system. Use a fogging oil to lubricate the piston and cylinder walls. Let all the water completely drain from the engine and wash it with a mild soap and water solution to remove grease and grime. Wipe off excess water and apply a light wax of some sort to help protect it from the elements. You can also spray it down with 303 Protectant to prevent sun damage and give it a nice shine. Replace the lower unit grease with recommended grease. Lastly, remove the prop and apply water resistant grease to the prop shaft and threaded areas. If the engine is staying on your boat while stored, you might want to look into an engine cover to keep the sun’s rays off of it if your boat cover does not already cover it.

Inboard Type Engines: First step to winterizing an inboard is to run them and get them good and warm. Shut the engine(s) off and change the oil and filter(s) while it is warm. The oil will pump out a lot easier while it is warm and helps remove the impurities. Next I remove the water plugs from the engine and let the fresh water drain out. Typically you will have (2) plugs in the lower part of the engine block right above the oil pan, two in the lower elbow of the exhaust manifolds, one on the bottom of the engine’s fresh water pump and one on the transmission cooler if so equipped. You may also have a separate power steering cooler depending on your setup. Consult your owner’s manual to be sure. If a water hose goes to it and there is a drain on the water side, probably best to drain it. Ensure that water runs out of each of these and leave all plugs out until all water is drained. It is a good idea to take a small screwdriver and run it into the area to make sure there is no debris blocking the water from exiting. If you have sea strainers, remove the plugs and drain the water at this time. When all water is drained you can put the plugs back into the block. If you have brass plugs, install them with fresh Teflon tape or replace o-rings as needed on plastic type plugs.

You are then ready to put antifreeze in the engine. Start by closing off the seacock and removing the hose from it. Pour antifreeze into it to displace the raw water. Depending upon the room available, I typically place an empty but clean 5-gallon bucket in the bilge area and put the hose into it that I removed from the seacock. Poor 4-5 gallons of RV antifreeze into the bucket and have some other ready to refill as needed. Start and run the engine at idle until antifreeze start streaming from the exhaust pipes. The amount of antifreeze you will use will vary depending upon your engine’s water system but a minimum of 5 and up to 10 can be used for each engine. Once antifreeze has expelled from the exhaust for 10-20 seconds, you can shut the engine off, remove the bucket and re-install the hose to the seacock. You can also change the fluid in the transmission(s) at this time. Remove each spark plug and use a fogging oil to lubricate each cylinder and piston. Mist the fogging oil or WD-40 on the engine lightly and wipe it off with a rag, inspecting things that might be out of normal like crack hose, cracked belts, pinched wires or the likes. Once this is complete you can move onto the next step of if you have two engines, the other engine.



Stern Drives: Upon removal from the water, you should completely clean and inspect your stern drive. Remove all plant life and debris to reveal a clean drive. Follow your owner’s manual directions and drain and change the gear lube. Pay close attention to the drain plug for debris or metal shavings that could let you know there is a problem. If a large amount of water comes out of your drive or a milky looking lube, you need to take further action to ensure the help of your drive. Water in your drive is not good on bearings and can cause major damage if not taken care of immediately. Refill the drive with the proper lubricant and replace the drain plug seals. If you drive does not have a magnetic plug on the bottom, I would suggest replacing it with one that does.

Check all cables and boots coming to the stern drive in the up position to ensure they do not have cracks or holes in them. Replace or schedule maintenance before putting the boat back in the water if you find any of these to be true. Grease any fittings and wipe off excess grease. Check fluid level in the hydraulic steering reservoir and check your owner’s manual for any additional recommended procedures. Remove the prop and grease the shaft and threads with water resistant grease.

Bilge Area: Make sure to clear any water deposits from the boat after wintering. Scrub the bottom with a stiff bristle brush and a mild soap water solution to remove any oil stains. Remove any debris including towels or cloth that can hold moisture. Check bilge pump area to ensure the switch and bilge pump area are clear of debris and they are operating properly. Bilge cleaning chemical is also available to aid with cleaning the bilge area to ensure any smell is eliminated. I have used dawn or downy in my soap mixture as well to give the bilge a pleasant smell.

Fresh Water System: Start this process by draining the system completely. Drain the hot water heater completely and bypass it. You can do this by disconnecting the in and out and connecting them together or purchasing a bypass kit that allows you to turn a level to accomplish this. Either way you do it, DO NOT let antifreeze get into the hot water heater. You will regret it if so (bad smell). Once the systems are drain, pump RV antifreeze through the lines until it is coming out of all faucets. I typically start with the faucet that is the farthest away and work my way back to the closest to the pump. Just gives a systematic way of doing it. Don’t forget the shower(s).

Head/Toilet: Have the holding tank pumped out at a approved facility. While they are pumping it out, fill the bowl with water and flush the toilet a few times while cleaning it.  If you have a boat that obtains it’s water through a seacock, shut off the seacock, remove the hose and drain the water in it. Reinstall the hose and tighten the clamp. Pour RV antifreeze down the toilet and flush. Use enough to antifreeze in the hoses, holding tank, Y-fitting and macerator pump. Generally 1-2 gallons per toilet will suffice.

Interior: The main thing to remember here is that excessive items left in this environment will tend to attract moisture and cause problems. So it is best to remove as much as you can and especially sheets, towels, linens and the likes. Turn cushions upright so as much surface is exposed allowing the least amount of surface for trapping moisture. Stowing docking lines, towables, flares and fenders is not recommended. Take them home, clean and inspect them and have them ready for the new boating season. Remove all items from freezer and/or refrigerator and clean completely. To keep your interior dry you can use products like Damp Rid or the likes. I prefer to get 5-gallon buckets and fill them half full of regular charcoal briquettes (Not Match Light!) and place them in strategic areas of the boat. A small boat might only need one but a 40 foot Cruiser would probably garner 3. This will keep the moisture out of the boat and help prevent mildew while eliminating smells. You can also place dryer sheets in hidden areas to help absorb moisture while giving a fresh smell. But I usually do this year round anyways.

Fuel System: This one always hurts but it is best to fill the tank completely. This helps avoid a buildup of moisture over the winter months that can lead to problems in the spring. Change your fuel filters and water separator and poor a fuel stabilizer like Sta-Bil.



Storage: Storing your boat is the final step to winterization. The size and type of boat will help determine if your boat is stored on the trailer in a storage unit or floating in the same slip it is in during the summer.

In Slip Storage: There is nothing wrong with storing your boat in the water if you make sure to take a few precautions. Make sure to double check that all seacocks are closed tightly and there are no leaks from packing or rudder shafts. Make sure your charging system is working to keep the batteries maintained over the winter months. Double check all bilge float switches and ensure the power switch is on. If the water that you store your boat in freezes, make sure the marina has bubblers or de-icing equipment. Periodically check on the condition of your boat or have the marina report to you on a set schedule.

Out of Water Storage: Completely clean the boat upon pulling it from the water. Remove all debris and barnacles from the hull and drive. This is a great time to put a coat of wax on the hull and get ahead of spring cleaning. Make sure to open all seacocks and drain all water from the boat. Remove the battery and put it in a place that you will remember to charge it every 30-60 days with a trickle charger. You can also purchase a battery maintainer that will keep the battery fresh until next season. Remove all items from inside and put the cover on.

That covers most of the basic systems that need to be winterized. Like I stated in the beginning, this is not meant to be 100% conclusive as all boats are different and you need to make sure to consult your boat’s owner’s manual. By following the suggested steps, you can safely winterize you boat and save yourself some money as well.


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