Boat Winterizing

Soon it will be time for Boat Winterizing. Depending on what type and size, it could be quick or it could take some time. A little runabout with no sink, head, or freshwater system onboard will not take that long, but take a 40' yacht, a book on winterizing a boat is in good order. When you look at it as a whole it could seem like a daunting task. Let's see how we can break it down to manageable parts, even on a large Yacht. This will be a basic plan, and we will be talking in generalities. So let's get started!

Boat winterizing begins with preventing any liquid, Fresh or Salt, water freeze. Let's put it in a basic list:

Fresh water Systems - includes your water tank(s) that go to your Galley, Head(s), holding tanks, A/C system, Deck wash down. (you may others)

Engines/Generators - includes their freshwater cooling system, PLUS their Saltwater System.

We can now do boat winterizing section by section. Get your Head hold tanks emptied and also empty your freshwater tanks. Some freshwater tanks have drains or you can disconnect the outlet hose on the bottom of the tank. If you can't get at the drain/hose or it does not have one, run your freshwater pump until the tank(s) are empty. In this way the tank empties and you can add nontoxic antifreeze that you can find in your marine store. The excess antifreeze will run to your bilge, where you already removed the water from. You want some antifreeze in the bilge incase rain water accumulates there during winter storage. At your freshwater pump that delivers water to the galley sink, head and shower, and deck wash down, etc, use the hose inlet hose there if you can or disconnect that one and use a temporary hose in the mean time. Have one end attached to the pump (inlet side), the other end put in the container of the nontoxic antifreeze. Marine stores sell a RV Antifreeze made for all freshwater systems, and is good to minus 50 below. With all your freshwater outlets, sinks, etc, shut off, turn on your pump. It will cycle like it usually does till it sucks up the antifreeze. Now turn on the furthest outlet first till the water coming out turns the color of your nontoxic antifreeze�normally red, and shut it off. Do this with the hot and the cold in the sink and shower. Do the next closer one and so on. Where ever your fresh water outlets are, remember your cockpit shower. Your water inlets to the heads have to have the antifreeze solution pumped thru, ending up in the holding tank, that's why we emptied it. So now your Heads, Galley, Deck, areas are done, including your bilge. Anything that water comes out of should be the color of the antifreeze. Do you're A/C systems the same way by find the pump and putting the inlet hose to the pump in the antifreeze solution. Run the A/C till the red comes out on all units.

When boat winterizing, your engines may have freshwater cooled engine(s). Here you will have to check the protection the freshwater is good to. This is usually a combination of freshwater and regular antifreeze. A tester can be found in any marine store or an auto parts store and are inexpensive. Check to make sure your antifreeze protection is where it needs to be in your particular area. Your engine(s) have a saltwater system also, which has to winterized. Take the inlet hose to the saltwater pump on your engine and put it in a container with the nontoxic antifreeze. Start your engine and see that the antifreeze gets pumped thru and out the exhaust. Do your other engine and/or generator the same way. Some like to change the oil and filter before they winterize the boat. Close all your seacocks and use any precaution that you need to in your area.

Taking the mystery out of winterizing a boat is basically what this is for. Always take any precautions you should. This is a generalization and should only be used as a reference along with other instruction that came with your boat.


Unfortunately, the boating season is winding down in many parts of the country and it is time to start thinking about protecting your valuable recreational asset. Winterizing a boat reminds me of the old commercial that says "pay me now or pay me later." The time and effort you spend now will have a definite effect on your boat's performance, or lack of it, and certainly save you time, effort and money come spring. You should remember that your insurance policy may not cover damage done by lack of maintenance or neglect.

The best place for your boat to be during the winter is out of the water, under cover, in a climate-controlled boat storage area. This, however, can be expensive. If don't have this option perhaps you should consider shrink-wrapping your boat. This, too, is a little expensive but provides a very protective cover. Short of these two items, make sure that your boat is well covered with a tarp or some other sturdy cover.

Your first step in winterizing should be to make a checklist of all items that need to be accomplished. Check the owner's manual of your boat and motor(s) for manufacturer's recommendations on winterization. If you are a new boat owner, perhaps you should employ the assistance of a friend with experience in winterizing or hire a professional to do the job. The following is a generic outline of areas which should be of concern to you, however, there are many resources on the Internet with more detailed and specific information.

Inboard Engine(s)

You should run the engine(s) to warm it up and change the oil while it is warm. This tends to allow impurities to be drained away with the oil. You should also change the oil filter(s). Flush the engine(s) with fresh water. You should circulate antifreeze through the manifold by using a pickup hose from the waterpump to a bucket of antifreeze. Start the engine and allow the antifreeze to circulate until water starts to exit the exhaust. This process will vary slightly depending on whether you have a "Raw Water" cooling system or an "Enclosed Fresh Water" cooling system. While you're in the engine room you should also change the fluid in your transmission. Remove spark plugs and use "fogging oil" to spray into each cylinder. Wipe down the engine with a shop towel sprayed with a little fogging oil or WD-40.

Stern Drive(s)

You should thoroughly inspect the stern drive and remove any plant life or barnacles from the lower unit. Drain the gear case and check for excessive moisture in the oil. This could indicate leaking seals and should be repaired. Clean the lower unit with soap and water. If your stern drive has a rubber boot, check it for cracks or pinholes. Grease all fittings and check fluid levels in hydraulic steering or lift pumps. Check with your owner's manual for additional recommendations by the manufacturer.

Outboard Engine(s)

Flush engine with fresh water using flush muffs or similar device attached to the raw water pickup. Let all water drain from the engine. Wash engine down with soap and water and rinse thoroughly. Disconnect fuel hose and run engine until it stops. It is important to follow a step by step process to make sure that all fuel is drained from the carburetor to prevent build-up of deposits from evaporated fuel. Use fogging oil in the cylinders to lubricate the cylinder walls and pistons. Apply water resistant grease to propeller shaft and threads. Change the gear oil in the lower unit. Lightly lubricate the exterior of the engine or polish with a good wax.


Fill your fuel tank(s) to avoid a build up of condensation over the winter months. Add a fuel stabilizer by following the instructions on the product. Change the fuel filter(s) and water separator(s).


Make sure the bilges are clean and dry. Use soap, hot water and a stiff brush to clean up any oil spills. Once the bilges are clean, spray with a moisture displacing lubricant and add a little antifreeze to prevent any water from freezing.

Fresh Water System

Completely drain the fresh water tank and hot water heater. Isolate the hot water heater by disconnecting the in and out lines and connect them together. Pump a non-toxic antifreeze into the system and turn on all the facets including the shower and any wash-down areas until you see the antifreeze coming out. Also put non-toxic antifreeze in the water heater.


Pump out the holding tank at an approved facility. While pumping, add fresh water to the bowl and flush several times. Use Vanish crystals or whatever your owner's manual recommends that will not harm your system and let sit for a few minutes. Again add fresh water and pump out again. Add antifreeze and pump through hoses, holding tank, y-valve, macerator and discharge hose. Again, check your owners manual to make sure that an alcohol-based antifreeze won't damage your system.


Once you have taken care of the system you should remove any valuables, electronics, lines, PFD, fire extinguishers, flares, fenders, etc. Over the winter these items can be cleaned, checked and replaced as necessary. Open all drawers and lockers and clean thoroughly. Turn cushions up on edge so that air is able to circulate around them or, better yet, bring them home to a climate controlled area. Open and clean the refrigerator and freezer. To keep your boat dry and mildew-free you might want to install a dehumidifier or use some of the commercially available odor and moisture absorber products such as "No Damp," "Damp Away" or "Sportsman's Mate."

Out of Water Storage

Pressure wash hull, clean barnacles off props and shafts, rudders, struts and trim tabs. Clean all thru-hulls and strainers. Open seacocks to allow any water to drain. Check the hull for blisters and if you find any that should be attended to you might want to open them to drain over the winter. While you're at it, why not give the hull a good wax job? It is probably best to take the batteries out of the boat and take them home and either put them on a trickle charger or charge them every 30-60 days.

In Water Storage

Close all seacocks and check rudder shafts and stuffing boxes for leaks, tighten or repack as necessary. Check your battery to make sure it is fully charged, clean terminals, add water if necessary and make sure your charging system is working. Check bilge pumps to ensure they are working and that float switches properly activate the pumps and that they are not hindered by debris. Make sure either to check your boat periodically or have the marina check it and report to you. If in an area where the water you are docked or moored in actually freezes, you should have a de-icing device or bubbling system around your boat.

By following some of the above suggestions, and suggestions given from the links provided, you should be in good shape for the winter. Do not, however, neglect to consult your owner's manuals for manufacture's recommendations on winterizing your boat and other systems. If you have not done a winterization job before or don't have an experienced friend to rely on seek out a professional to do the job for you.

Content provided by

Winterize Your Boat

Winterize Your Boat

How to Winterize Your Boat

User-Submitted Article

Winterizing your boat is very important. If you live in a zone where the weather freezes and you don't have an indoor heated storage it is imperative. If you don't winterize your engine block, it will freeze and possibly crack, thereby ruining your boat. Additionally, it is a great time to cleanup and repair your boat so that it will give you many years of reliable pleasure.

Difficulty: Moderate


1.    1


First wash and wax the hull, including the bottom and deck. Check for damage and fix.

Drain and clean the bilge.

Clean the interior including the windshield and other glass. Include the instrument panel and don't forget any storage areas. Clean and treat any upholstery and trim. Vacuum and wash or clean the carpet.

Drain, clean, lubricate, and winterize the head.

Check all fire extinguishers

Drain and winterize the water system.

Inspect and lubricate all controls and cables

Inspect clean and treat standing and running, rigging, sails, canvas (including boat cover) and mooring Lines.

If possible remove electronics for storage.

Use dehumidify & mildew control.

Remove, clean, treat and store the dingy.

2.    2


Remove and inspect the propeller.

Add a fuel stabilizer to the fuel tank as per instructions.

Use a flush attachment to flush the engine.

Run the engine at low RPM for several minutes to get fuel lines, carburetor etc., full of treated fuel.

Change the motor oil and filter then run the engine to make sure oil is circulated and motor parts lubricated with new oil.

Use fogging oil in the carburetor while engine is running and run the engine a few minutes. (see manufactures instructions)

Drain and replace the gear case/vertical drive unit lubricant.

Remove the spark plugs and spray fogging oil into the cylinders. Turn over the engine to distribute the fogging oil.

Leave the wires disconnected and re-install the spark plugs.

Winterize the cooling system with appropriate anti-freeze. (follow manufacturers instructions)

Remove the battery, check water level, charge battery and store in a cool dry location. Charge periodically or attach a battery float charger.

Disconnect any portable fuel lines and tanks.

Spray a rust preventative on engine and other rustable parts.

Check all belts and hoses.

3.    3


Check tires and wheels for air pressure and damage.

Inspect all rollers and replace or fix any damage.

Lubricate the wheel bearings.

Inspect, clean and lubricate the winch.

Clean and lubricate ball and hitch.

Inspect and test lighting fix as necessary.

Read more: How to Winterize Your Boat |

How to Winterize a Boat Motor

By an eHow Contributor

I want to do this! What's This?

It signifies the end of summer when you pull the boat out of the water and get it ready for winter storage. Of course, if you own a boat you know it's not quite that simple. You have to winterize the motor, which is probably the most important thing you do regarding maintenance of your boat. The following guidelines will help you take the right steps to winterize your boat motor.

Difficulty: Challenging


Things You'll Need:

1.    1

Pull your boat out of the water. Thoroughly wash and clean the entire boat including the deck and the cockpit areas. Don't forget to run and drain the bilge pump so nothing is left in that line and leave the plug out while in storage. If your boat has toilet facilities, drain, flush and clean these areas as your boat manufacturer recommends. Leave the storage areas open so moisture doesn't build up inside. Make needed repairs or make a list of things that need to be repaired before putting the boat back in the water next boating season. Place life jackets in an area where they can air out.

2.    2

Take special care to "winterize" your boat motor. Fill the fuel tank first with some fuel stabilizer and second with marine fuel. Run the motor long enough to make sure the gas treatments have reached the fuel lines and engine area. This will keep the fuel remnants from spoiling in the tank or turning into a gummy varnish, which may ruin your tank, not to mention the condensation and oxidation that may occur.

3.    3

Flush out the cooling system to clean out or "flush out" sediment or bits of rust. Start this by removing the plug to drain the water from the engines. Use a "flushing kit" that you can purchase from a boat supply or boat dealer. Then, pump back into the cooling system some anti-freeze. If you don't flush out the cooling system, you can have ice freeze in the line and seriously damage or ruin your engine.

4.    4

Spray the engine with oil that will help to prevent rust build up. It is recommended that you use fogging oil that you can purchase at a boat supply or boat dealer. This type of oil is specially formulated to not slide off the boat cylinders, but rather stick to it. The fogging oil can be sprayed through the spark plug holes once the engine has cooled down enough to remove them. Don't forget to replace the oil and the oil filters as well. Change out the lubricant in the lower unit gear casing. You don't want any water left in these areas as it will freeze and cause damage to the gear casing.

5.    5

Take a good look at the prop on the boat. This is your chance to examine it for nicks and damage. If your prop isn't in good condition it can cause a "trickle down effect" to damage other parts of the engine.

6.    6

Refer to your instruction book or owner's manual to be sure that you can use a moisturizing spray lubricant, like a silicone product, on the electrical terminals and fuse panels. Check out your steering system and make any necessary adjustments.

7.    7

Cover your boat with a boat cover made for your model of boat if the boat will be stored in an outdoor area.

Winterize Your Boat 1

Eliminate Freeze Damage Also Use Your Boat Year Round



For Information on How to Protect Your Engine Visit



Tips & Warnings

  • Read the owner's manual provided with your boat motor. It is always best to follow the recommended guidelines for winterizing the boat motor per the motor's manufacturer.
  • There are many boat service companies or boat dealers that have services to winterize boats, so if you don't feel comfortable doing the winterizing yourself, hire one of these professional companies to handle the process for you.

Read more: How to Winterize a Boat Motor |