With colder weather settling in around Puget Sound and the holidays fast approaching, it’s time to ask the question: is my boat ready for winter?

The Northwest’s reputation for relatively mild winters can make it tempting to tempt fate and not winterize your boat. But last year’s long cold snap and heavy snows should be a reminder that you can never take weather for granted here.

If you do, you could be putting your boat and your pocketbook in big jeopardy.

“We only have that couple weeks (each winter) when it gets bad and people get complacent,” said Scott Anderson, co-owner of CSR Marine boatyards, which offers winterizing services for boaters. “Anything that freezing water can break, we’ve seen it happen.”

Engine blocks, water pumps, through-hull valves, even raw water strainers can succumb to the incredible expanding force of frozen water. And while the freezing is bad, it’s the inevitable thaw that causes the real problems. Just imagine the water pouring in from that broken raw water strainer, and you get the picture.

Adam Chamberlin, owner of Seattle Mobile Marine, has seen his share of big repair bills caused by owners who just didn’t take the time to get their boats ready for winter.

“People definitely like to skimp out on winterizing and that can cause problems,” Chamberlin said. “One guy had a bill for $9,0000 (to replace his engine) and his boat was fairly new. He was a new boater and he just didn’t know.”

Three Sheets Northwest recently chatted with Anderson and Chamberlin to get their thoughts on what local boaters should do to get ready for winter. The pros know it’s not a difficult task, but for people who don’t know a dipstick from a coat hanger, the thought of changing oil or running antifreeze through a cooling system can be daunting. For those folks, CSR Marine, Seattle Mobile Marine and many other boat maintenance firms provide winterizing services for a few hundred dollars.

But for the committed DYIer, the following are some tips for Northwest winterization. All boats are different, so remember to always check with the your engine and boat manufacturer on specific recommendations. If you want to share your own suggestions—or dispute the ones below—please add your thoughts in the comments section following the story.

The engine room

When it comes to freezing weather, perhaps the most vulnerable equipment on your boat is the engine. This is especially true for boats that are stored on trailers or on the hard during winter. Water temperatures in the Northwest tend to help protect in-water boats from experiencing freezing temperatures as quickly—but only for awhile.

Save your engine by getting the water out before it freezes.

“What we see in the boatyard is if the boat is out of water and on the hard, with three days of freezing weather, that is when you really start having trouble,” Anderson said. “If the boat is in the water, you really need a weeklong freeze to cause problems.”

Water trapped in the heat exchanger, engine block, pumps and exhaust manifolds can all cause problems. Your goal is simple: get the water out.

First: If you have a diesel engine, fill up your fuel tanks to prevent condensation from introducing water in the tanks during the winter. You might also consider adding a biocide to prevent any growth during the off-season.

For gasoline engines, you can either drain the tank or fill it and add a fuel stabilizer to preserve the fuel for several months.

Second: Change the oil and filters. This will help prevent corrosion and deposits from accumulating during the winter. While you’re at it, check and replace the transmission oil and the coolant, if the engine is fresh water-cooled. Getting these chores done now means less work before next boating season starts.

With gasoline engines, disconnect the fuel supply and run the engine until it stops. This keeps gas that could deteriorate out of critical areas in the engine.

Also, take this opportunity to use a fogging oil on the engine and in critical areas to prevent corrosion. Refer to your engine manual for details on how to do this.

Third: Drain standing raw water from the engine. In general, drain the raw water side of the engine, including the heat exchanger, raw water pump and exhaust. Some people also recommend running a mixture of antifreeze through the raw water systems before draining to leave a protective coating on metal parts. And as Anderson warns, don’t forget to empty your raw water strainer.

The rest of the boat

Outside of the engine room, more threats lurk in winter. Busted water pumps, mold and mildew can also cause their share of problems if left to fester.

Solar powered vents like this can keep air circulating during winter.

First: Close off all through-hulls below the waterline. Many boats have been sent to the bottom by a valve that has busted from freezing water.

Second: Check your batteries and if using wet cells, make sure they are topped off with distilled water.

Third: Prepare your fresh water system. There are several approaches to this. Some people recommend using an RV-style pink antifreeze designed for water systems. Others recommend simply draining the fresh water tanks to at least half full, turning off the water pump and leaving the faucet open. This will allow the water some room to expand. You can also fully drain the system and disconnect hoses connected to pumps, especially in the low points of the system where water will naturally collect.

Fourth: Keep the air dry and moving. There are several approaches to this. Many boaters deploy a strategy of circulating fresh air during the winter with fans, vents and dehumidifiers. But it is critical that fresh, drier air can replace damp air below. Something as simple as a 40-watt lightbulb can generate enough heat to move air in smaller boats or tight spaces. Removing cushions and other fabrics that can absorb water is a good idea, as is opening hatches to make sure air can circulate in those nooks and crannies as well. Some boaters opt for dehumidifying systems that remove water from the air and drain it into a sink. But be careful with this approach if you have a wooden boat.

Fifth: Remove and stow all unnecessary above-deck equipment. Sailors should consider removing the headsail from the furler and stow in a dry area either below decks or at home. Depending on its cover and condition, the main sail can remain on the boat during winter.

Sixth: Don’t forget the outboard. Whether you use an outboard to move your boat or your dinghy, don’t forget to read the owner’s manual and make sure the motor is ready for winter too. Flush the cooling system with fresh water. Run the gasoline in the engine dry. Check the lower unit oil. And make sure to use fogging oil on the engine to prevent corrosion.

Are you ready?

For those who figure they can just keep a cabin heater going during the winter and call it good—don’t bet on it.  Electricity at most marinas is spotty at best during periods of cold weather. Unless you are checking on the boat daily, you might find that your first line of defense agains the cold fails you when you need it most. 

And CSR’s Anderson has this final piece of advice for boaters: “It is always really good to read your insurance polices before winter. You’re allowed to be stupid, but not too stupid.”

Three Sheets Northwest welcomes your specific suggestions for riding out winter in the Northwest. Please feel free to leave your ideas in the comments section below.