Many boaters have heard the term “winterization,” thinking it pertains to getting a boat ready for cold weather. Much of the process does focus on making sure that water won’t remain in a boat’s engine or onboard systems, so it won’t freeze during a winter layoff, but the word actually applies to a vessel that’s going to sit dormant for a long time in any climate.
“Anytime you’re going to lay the boat up for more than 30 days, it’s a good idea to go through this process,” said Eric Jones, technical support manager for Boatswain’s Locker in Costa Mesa, Calif. “Anytime you have raw water sitting in your engine, it’s going to corrode.” This is especially true for boats run in saltwater.
Winterization is a process that involves removing any standing water from engines and drives, where applicable, as well as onboard systems that use water like sinks, showers and toilets. For do-it-yourselfers, the process is straightforward regardless of the type of engine. We’ll start by looking at winterizing a typical sterndrive boat, followed by one powered by an outboard and then diesel engines. Some steps are used for all three propulsion types.
Sterndrives
Dan MacNamara is the owner of Team Archer Marine in Huntington Beach, Calif., but he spent many years at a marina on Lake Minnetonka in Minnesota, where winterizing a boat was a big part of the income stream.
Regardless of the type of engine, the first thing an owner should do is add a fuel stabilizer like Sta-Bil to the fuel tank. Make sure you use the product labeled “Storage” because it was developed specifically for treating fuel that is going to sit for an extended time. A chart on the bottle will tell how many ounces of stabilizer should be added per gallon of fuel. Many mechanics like MacNamara and Jones recommend filling a boat’s fuel tank before winterizing it to prevent condensation forming in the reservoir. Others say to put away the boat with as little fuel in the tanks as possible and still treat the gas or diesel.
After adding the stabilizer, with at least enough fuel left in the tank to run the engine to complete the winterization process, the first thing to do with a sterndrive-powered boat is get propylene glycol-based “pink” anti-freeze through all the internal passages to protect them. Put a few gallons of the anti-freeze in a portable tank on the boat’s swim platform. Connect hoses from this tank to a set of earmuffs that you would use to run the engine on a garden hose. After the engine is warmed, switch over from the freshwater to the anti-freeze and let it run through the motor.
“You want to run it until you start to see a little antifreeze coming out of the exhaust,” says MacNamara.
Next, turn off the engine so the oil and the lower-unit gear lube can settle in the pan and gearcase so they can be drained while still warm. While that is happening, remove the drain plugs in the exhaust manifolds. After the plugs are removed, water should empty quickly and easily. If the flow is restricted, take an awl or even a straightened paper clip to poke up in the hole the drain plug threads into to unclog any debris that may be in there.
Leave the drain plugs out to ensure that any water from condensation can drip out. To keep track of the plugs and to remind you to re-install them in the spring, put them in a Ziploc bag and tape it to the steering wheel. If the engine has closed cooling, top off the coolant and run anti-freeze through the heat exchanger passages.
While some people might think spring is the time to replace the engine oil and gear lube, many mechanics prefer the end of the season because used oil provides less protection for internal engine parts than new. MacNamara drains the gear lube from the drive first and then replaces it. He also recommends replacing the water-pump impeller every other year. “I’m always adamant about the owners changing their impellers at least every other season,” he says.
Next up is to change the engine oil and filter, plus the water-separating fuel filter if the boat has one. MacNamara always uses an engine manufacturer’s oil and filters. Mercury’s products are branded as Mercury or Quicksilver.
For an inboard-powered boat, the transmission oil should be changed, too. For wakesports boats, drain the ballast system and park the trailer with the bow up as high as possible. On a larger cruiser, any type of water system including sinks and toilets should have the pink anti-freeze run through it.
Outboards
The biggest advantage of an outboard motor is that it is designed to run in a vertical position, which means that water naturally drains out. Start the winterization process by putting Sta-Bil for Storage in the fuel tank and run anti-freeze through the motor, either using the same plastic jug and earmuffs or by filling a shallow pan with anti-freeze and putting the outboard’s lower unit in the pan. After you see the anti-freeze coming out of the exhaust, shut off the fuel supply to the motor and let it run out until it dies. That coats everything inside with the anti-freeze.
For carbureted outboards, spray fogging oil into the carbs and with fuel injection, remove the air box and try to shoot it into the intake. Oil injected motors don’t need as much fogging because the internal components are already protected by the oil.
With two- or four-stroke outboards, drain the lower unit gear lube and replace it. As he does with sterndrives, MacNamara recommends replacing the water-pump impeller in the lower unit. On four-stroke outboards, change the engine oil annually.
If you’re wondering what it will cost to do the work yourself, Team Archer Marine charges $200 per hour for labor and winterization usually takes three to four hours plus parts.
Diesels
Winterizing a diesel is similar to the process for a sterndrive. Jones starts with filling the fuel tanks to at least 90% capacity with the proper fuel additive. He also recommends covering the fuel tank vents so water can’t enter. This is a step that even many professionals miss.
Next, depending on how the engine takes in water, replace the water with propylene glycol anti-freeze until it comes out the exhaust because many diesels have plastic or fiberglass mufflers that can crack in cold weather. Check the closed cooling system for correct anti-freeze level. Drain all water out of the heat exchangers and any other systems that take in raw water directly.
After the engine cools for about 15 to 30 minutes, drain the oil and replace it, regardless of how few hours the boat ran for the previous season.
“Many people will say I only put 10 hours on it, but the manual says X number of hours or annually,” says Jones. The reason for this is that oil becomes less protective as it ages. The fresh oil will coat the engine’s internal surfaces more effectively. Boatswain’s Locker is a dealer for Yanmar diesel engines and recommends lubricants and filters from the engine company. To put away the boat for its long rest, finish the process by putting plastic bags over the air cleaner and disconnect the battery cables.
As with gasoline inboards, change the transmission oil where applicable. Jones estimates a winterization takes four to six hours and Boatswain’s Locker charges $165 per hour.
