Preparing Your Boat for Winter

June 23rd, 2009

by Captain Alan Stopko

Depending upon the type of boat one owns and its locale often determines whether we boat throughout the year or put our boat up for the winter. In North Carolina we are fortunate that we have a choice and, in my opinion, some of the best boating days are in the winter.

However, what should I consider doing if I will not be using my boat during the winter? The primary concern is damage caused by water, freezing and rodents. The following are ideas that have worked for me.

Preparation for wintering or off-season:

• Clean the boat by washing & polishing the hull and metal work.

• Clean upholstery with a good vinyl cleaner and conditioner. Repair any rips.

• Check your electric system insuring all systems, lights, switches are working.

• Change the oil and filters on all engines.

• Replace water separating fuel filters.

• Remove and clean gasoline engine flame arrestor with general purpose cleaner. Dry before replacing. This can improve fuel mileage.

• Change your fuel filters. Most boats have more than one.

• Inspect belts and hoses. If belts have cracks or hoses are soft, replace.

• Drain and refill the sterndrive. Make sure to grease the sterndrive gimbal bearing and engine coupler. Check the bellows. This is best done by a licensed mechanic.

• If steering cable has grease fittings, lubricate with grease from a hand-operated grease gun while cable is fully retracted into cable housing.

• Lubricate all steering system and throttle/shift system pivot points with SAE 30 motor oil.

• Add a gas stabilizer to the gas tank. Read instructions carefully for amount to use per gallon. Run engine for approximately 15 minutes to ensure that the additives reach the gas in your fuel lines and engine. I have always filled my tanks to reduce condensation and it seems to have worked well for 35 years and 4 boats. Always started in the spring without a problem.

• Remove interior cushions and jump seats and store in a cool dry place. Otherwise, place cushions on end to allow sufficient ventilation. Removing eliminates the chance of rodents chewing through your seats.

• Clean out the cooler, refrigirator, ice maker and wash down with bleach and water solution. Leave doors open.

• Now is also a good time to check all storage compartments. Remove all the extra weight that has acumulated from stuff we don’t use or need.

• Replace impellers on inboards and sterndrives at least every 24 months.

• Drain porta potti and fresh water system. Add FRESHWATER antifreeze to water tank and porta potti.

• Store the boat in a garage or other facility if available. If not, cover the boat with your mooring cover after the interior has been allowed to dry out. Make sure you have sufficient air movement. Moisture and poor air circulation are the main reasons for rot and mildew.

• To keep your boat dry and mildew-free, install a dehumidifier or use commercially available odor and moisture absorber products.

• Stern drives should be stored in the full down position and perpendicular to the stern. This reduces strain on exhaust bellows and universal joint bellows AS WELL as preventing muskrats from chewing holes that can sink your boat next spring.

• Remove all water in the bilge making sure it’s clean and dry. Water could freeze, expand and crack something.

• The engine should be fogged and all water removed from inside the engine and replaced with antifreeze. This is best done by a licensed mechanic.

• If storing your boat on the trailer you should block the trailer wheels so they are off the ground reducing tire deterioration. Loosen the tie down straps to reduce stress on hull. Leave the drain plug out while canting the boats bow higher than the stern so rainwater will not accumulate in the bilge. This is also a good time to replace wheel bearings, grease the bearings and apply touch up paint.

• Remove the batteries, fill with distilled water only, and store in a warm, dry place. Slow charge once every 45 days.

Most all of these suggestions can be done in a weekend by the average boater. When I boated on the Great Lakes I always used a contractor to winterize my engines. Leave the technical stuff and responsibility to the pros.

This information is strictly for general informational purposes. As with any critical service work, you should consult a qualified mechanic for your boat, engine and systems.

Captain Alan Stopko is a US Coast Guard Master with 100 Ton Rating. His experience includes near coastal, Great Lakes, Chesapeake & Delaware Bays, the Inter-Coastal Waterway and inland lakes and rivers. He is also a US Power Squadron Vessel Safety Examiner and conducts local boating safety and on water training classes. You can reach Captain Stopko at, or by calling 704 895-6993.