Winterizing Your Boat: 10 Steps to Keep Her Shipshape for Spring
So, the leaves are falling, the air's getting crisp, and you're starting to think about tucking your beloved boat away for the winter. Think of winterizing like giving your boat a cozy blanket and a "Do Not Disturb" sign for the off-season. Proper winterization prevents freeze damage, corrosion, and other nasties that could turn your pride and joy into an expensive lawn ornament.
Step 1: Dust Off the Owner's Manual
I know, reading manuals is about as exciting as watching paint dry. But every boat has its quirks, and the manufacturer’s guidelines are your cheat sheet to avoiding costly mistakes. So, grab a cup of coffee and give it a skim—you might thank yourself later.
Step 2: Show the Engine Some Love
For Inboard Engines:
- Change the Oil and Filters: Old oil can corrode engine parts. Think of it as giving your engine a fresh cup of joe.
- Flush with Fresh Water: Remove salt, dirt, and whatever else you picked up out there.
- Add Antifreeze: Run non-toxic antifreeze through the cooling system. Frozen engine blocks make expensive paperweights.
- Fog the Engine: Spray fogging oil into the carburetor or spark plug holes to coat internal parts.
- Wipe It Down: A light coat of WD-40 can help prevent rust. It's like moisturizer for your engine.
For Outboard Motors:
- Flush and Drain: Run fresh water through and let it drain completely.
- Clean the Exterior: Soap, water, and a bit of elbow grease.
- Drain the Carburetor: Prevents fuel from gumming up the works.
- Lubricate Moving Parts: Grease all fittings and the propeller shaft.
- Protect the Finish: A light coat of wax keeps it shiny and new.
Step 3: Fuel Stabilization—Not Just a Fancy Term
- Fill 'Er Up: A full tank prevents condensation, which is code for "water in your fuel is bad."
- Add Fuel Stabilizer: This keeps the gas fresh and prevents ethanol issues.
- Run the Engine: Let the treated fuel circulate. It's like giving your boat a flu shot.
Step 4: Drain and Defend the Plumbing
- Empty Freshwater Systems: Sinks, showers, tanks—the whole shebang.
- Add Antifreeze: Use non-toxic, marine-grade stuff. Pink is usually the color of choice.
- Flush the Head: Pump out the holding tank and run antifreeze through the toilet and hoses. Trust me, frozen sewage is a problem you don't want.
Step 5: Bilge TLC and Drain Plugs
- Clean the Bilge: Soap, water, maybe a degreaser if it's gnarly.
- Dry It Out: Moisture leads to mold and mildew. No thanks.
- Remove Drain Plugs: Let any remaining water escape. Just remember to put them back in spring (don't ask how I know).
Step 6: Battery and Electrical Care
- Fully Charge the Battery: A charged battery is a happy battery.
- Disconnect and Store: Remove the battery and keep it in a cool, dry place.
- Inspect Wiring: Look for frayed wires or corrosion. Mice love nibbling on these over winter.
Step 7: Spa Day for Your Boat
- Wash the Hull: Remove grime, algae, and that mystery gunk.
- Inspect for Damage: Now's the time to spot and fix any issues.
- Wax On, Wax Off: Protects against moisture and those sneaky UV rays.
Step 8: Clear the Decks—Literally
- Remove Electronics: GPS, radios—anything that could grow legs or suffer from the cold.
- Safety Gear Check: Life jackets, flares, extinguishers—store them properly and replace if needed.
- Personal Items: Fishing gear, water toys—unless you want them turned into rodent condos.
Step 9: The Big Cover-Up
- Choose a Quality Cover: Invest in a good, fitted cover. Cheap tarps are about as reliable as a politician's promise.
- Consider Shrink-Wrapping: For the ultimate protection, professional shrink-wrapping is gold.
- Ensure Ventilation: Mold and mildew love stagnant air. Don't give them a free pass.
Step 10: Keep an Eye Out
- Periodic Checks: Swing by after big storms or heavy snow.
- Pest Patrol: Look for signs of critters setting up shop.
- Security Measures: Make sure locks are secure and alarms are set if you have them.
Bonus Tips for In-Water Storage
If you're leaving your boat in the water (you brave soul):
- Close Seacocks: Except for cockpit drains.
- Check Bilge Pumps: They need to be in top form.
- Use De-Icers: Keep ice from forming around the hull. Boats and ice mix about as well as oil and water.
Winterizing your boat might not be the highlight of your year, but think of it as an investment in peace of mind. When spring rolls around and you're not elbow-deep in costly repairs, you'll be patting yourself on the back. So grab that wrench, put on some good tunes, and get to it. Your boat (and your wallet) will thank you.
Hi—I’m Jim Walker
I grew up in a Florida boatyard, earning pocket money (and a few scars) by rebuilding outboard carbs before I could drive. That hands-on habit carried me through a Ph.D. in mechanical engineering, where I studied how salt water quietly murders metal.
I spent ten years designing cooling systems for high-horsepower outboards, then joined JLM Marine as CTO. We bench-test every new part in the lab, but I still bolt early prototypes onto my own 23-foot skiff for a weekend shake-down— nothing beats real wake and spray for finding weak spots.
Here on the blog I share the fixes and shortcuts I’ve learned so your engine—and your day on the water—run smooth.

For Boat Owners:
To assist you in maintaining and repairing your marine engines, we hope the following resources may be of use:
- Mercury Serial Number Guide
- Owner's Manuals from Mercury
- Official Model Number Reference Guide PDF from BRP
- Johnson Serial Number Guide
-
Boat Accessories from JLM Marine
About JLM Marine
Founded in 2002, JLM Marine has established itself as a dedicated manufacturer of high-quality marine parts, based in China. Our commitment to excellence in manufacturing has earned us the trust of top marine brands globally.
As a direct supplier, we bypass intermediaries, which allows us to offer competitive prices without compromising on quality. This approach not only supports cost-efficiency but also ensures that our customers receive the best value directly from the source.
We are excited to expand our reach through retail channels, bringing our expertise and commitment to quality directly to boat owners and enthusiasts worldwide.
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