What a season it has been! As it comes to a close, it’s time to give your boat the tender loving care needed to ensure next season will be just as great.
This guide to winterize works for the typical outboard and inboard boats we use in Central Virginia. We recommend you also refer to your boat and boat engine manual for specific winterization requirements.
Also, jet skis often have unique winterization requirements, so you must follow the manufacturer’s instructions. Firstly, never run your engine without adequate cooling water - expensive damage can occur within seconds!
Couple of Preliminary Tips Regarding Fuel
If you are using non-ethanol fuel, fill the fuel tank so condensation cannot form in the tank over the winter. However, if are using ethanol fuel try and have the fuel tank as empty as possible! The reason for this is ethanol fuel absorbs moisture from the air and if enough moisture gets into the fuel phase separation occurs and moisture becomes water in the bottom of the fuel tank. The risk of condensation in the fuel tank is less of a problem than dozens of gallons of ethanol fuel absorbing moisture from the air all winter.
● Remove and drain any portable fuel tanks if possible.
● Add a good quality marine fuel stabilizer to the fuel in the correct ratio to keep the fuel fresh for next season. This is a must!
Oil for an Inboard Engine Steps
● If you have inboard engine run it for a short while to warm up the oil.
● Then drain the engine oil and replace the oil filter. (You may need a special suction type oil changer to remove the oil).
● Refill the engine with the correct grade of oil in accordance with your engine manual.
● Start the engine and check for oil leaks then just before you shut it down spray some fogging oil in the air inlet.
Oil for an Outboard Engine
● If you have a two stroke outboard engine run it for a few minutes at idle then spray some fogging oil in the air inlet just before you stop it.
● On four stroke outboards you need to drain and refill the oil and install a new oil filter. Refer to your specific engine manual for the correct requirements.
● Remove the spark plugs and spray some fogging oil into the cylinders to stop internal corrosion during the winter.
● Important: replace the spark plugs and tighten them correctly! (On four stroke outboard engines you will have to remove the spark plugs and spray fogging oil in the cylinders as spraying fogging oil in the air inlet does not work very well)
● If possible crank the engine a few revolutions with the spark plugs removed to disperse the fogging oil. (If you disconnect the engine safety stop lanyard you can usually crank the engine without the spark plugs firing).
Drain Cooling Components
● On the direct (raw) water cooled inboard engines that most of us use on the lakes of Central Virginia you will need to drain all the water out of the engine cooling water components, hoses, engine block and engine exhaust manifolds.
● There are usually drain valves and plugs in various locations on the engine to enable draining of trapped water.
● Refer to your specific engine manual for the correct procedure. On indirect cooled inboard engines check the coolant level and anti-freeze concentration in the sealed side of the cooling system and add anti-freeze as necessary.
● Drain all water from the raw water system in accordance with your engine manual.
Sealing and Other Winterizing Tasks
● Soak some rags in fogging fluid and plug up the exhaust outlets on the stern of the boat if your craft has them. This helps keep damp air, condensation and vermin out of the exhausts.
● Seal up the air inlet with masking tape or similar if possible to help keep damp air out of the engine.
● Drain any water from the fuel filter/water separator if installed and replace the fuel filter element.
Change the Lower Unit or Outdrive Oil
● If you have an outboard or inboard engine, drain the oil from the outdrive/lower unit. Replace it with fresh oil of the correct type in accordance with your engine manual.
● If the old oil comes out very cloudy or grey in color you may have water getting into the oil. This can cause severe damage to the internal parts of the unit very quickly so contact Sterling Aero Marine Services for advice.
● On outboard engines and outdrives it is often recommended that the lower unit be removed at regular intervals to check the water pump components. Check your engine manual and contact Sterling Aero Marine Services if this is required.
Final Winterizing Checklist
● Grease all steering and pivot joints. On outboards and outdrives there are usually grease fittings installed for this purpose. Use good quality marine grade grease. If installed check the trim and tilt hydraulic reservoir oil level. Add the correct oil in accordance with your engine manual.
● Spray the engine and electrics with a good quality marine corrosion preventer.
● Inspect the propeller for damage to the blades and hub. Even a small “ding” on the blades can affect the balance and performance of the propeller and increase your fuel consumption. If your propeller is damaged you should seriously consider replacing it with a new prop or sending it out to a propshop for overhaul. Sterling Aero Marine Services can arrange this for you.
● If your battery is not a sealed type check the electrolyte level and add distilled water as necessary. If possible remove the battery and store it in a garage or similar safe place away from children and pets. Connecting a battery maintainer type of charger to the battery is a good idea as a charged battery will not freeze. Use a similar procedure for trolling motor batteries.
● If you are lucky enough to own a boat big enough to have an on-board potable water system, drain the water. Then add RV non-toxic pink anti-freeze to the water tank and pump some though the system to protect the pump and components. Drain any on board toilet.
● Give the boat a good clean and vacuum out the inside. Those cookie crumbs and half eaten sandwiches under the seat will act like a magnet to vermin. Who will then build their winter nests in your upholstery and seats!
● Remember the trailer! If you trailer launch your boat on a regular basis the trailer bearings will have ingested water. Remove the wheels and hubs then clean and grease the bearings using marine grease designed for boat trailer bearings. While the trailer wheels are off inspect the tires. Trailer tires rarely wear out but they do rot from UV exposure. Replace any tires that show signs of cracking and deterioration of the sidewalls. Trailer tires require a much higher air pressure than car tires so inflate the tires to the pressure written on the tire sidewall.
● Install a cover to keep the elements out. If you are using a fitted cover lubricate the cover securing snaps with silicone grease so they will not seize up over the winter and rip your cover when you try to remove it in the spring! If your boat will be outside for the winter consider covering it with a tarp as most fitted boat covers are not strong enough to with stand a heavy snowfall.
● Make a list of all the items you winterized so you can refer to it when commissioning the boat in the spring!
Time spent on winterizing your boat will avoid costly problems the next boating season, and will get you back on the water quicker and with less frustration. Remember, always think "safety" and carry out any boat repair and service in accordance with the manufacturer’s instructions. We tend to think of our boats as toys, but in their own way, they can be more dangerous than a motor vehicle if not maintained.
ABYC Certified Marine Technician
Sterling Aero Marine Services