Winterizing Your Outboard Boat – Why It Matters & Key Steps

As the fall rains deepen and Puget Sound temperatures dip, now is the time to think about winterizing your boat. Even in the relatively mild winters here in northwest Washington, taking the right offseason precautions will protect your engine, extend its life, and make your spring launch far smoother.

Why Winterize?

1. Prevent freeze damage & corrosion
   Water left in engine passages, gearcases, or cooling systems can freeze or create condensation, leading to cracked blocks, corroded internal parts, and sticky valves.
   In the San Juan / Salish Sea region, water temperatures rarely fall below ~45°F, but short cold snaps or nights with frost can cause trouble if parts are left wet or exposed.
2. Avoid fuel-system issues
   Fuel left untreated over months can oxidize, gunk up injectors or carburetor parts, and clog filters.
3. Seal against moisture & corrosion
   Fogging is essential to coat internal engine parts with a protective film. Also, applying corrosion inhibitors and protecting exposed surfaces helps in a saltwater environment.
4. Catch issues early
   During winterization, you may uncover loose mounting bolts, worn seals, or weak anodes — problems you’d rather fix now than find in spring.

Key Steps in Winterizing Outboards

Here’s a simplified checklist tailored to small boats with Mercury outboards. Always consult your specific engine’s service manual for details.

Local Considerations for Anacortes / Salish Sea Boaters

• Because most of our winters hover in the 35–45 °F range, catastrophic freezing is less common — but that doesn’t mean components shouldn’t be protected. A few hours of frost or overnight exposure can still cause damage, especially in engine compartments with little insulation.
• Many local boaters keep their vessels in the water over winter. If you do so, make sure you heat your engine compartment (to prevent internal freezing), monitor shore power reliability, and ensure your shrink-wrap or tarp doesn’t trap water or block ventilation.
• When storing out of water in Anacortes-area yards or marinas, ensure your haul-out is early enough to avoid the worst of fall storms. Use proper stands, secure the boat from shifting, and consider having our shop apply professional shrink-wrap if doing long-term outdoor storage.
• If your boat’s marina slips are in exposed locations (north or windward sides), anticipate extra spray or wind-driven moisture and protect vulnerable components accordingly.

DIY or Bring It In to Salish Boat Company?

If you’re handy, you can tackle many of these steps yourself — Mercury publishes a helpful “How to Winterize Your Outboard” guide with a reliable checklist. Here’s one useful how-to video (for a Mercury outboard) you can follow:

Mercury Marine – How to Winterize Your Outboard (video guide)

However, if you’d rather put it in expert hands — or simply want peace of mind — bring your boat to Salish Boat Company in Anacortes. Our certified technicians are familiar with local conditions, Mercury outboard systems, and all the nuances that come with winter storage in the Salish Sea. We can perform full winterization service, inspect for hidden issues, help you with shrink-wrapping, and prepare a spring re-commissioning plan.

You can learn more about our services and schedule an appointment via

Bottom line: A thorough winterization is time and money well spent. It reduces the risk of downtime, major repairs, and surprises come spring. Whether you DIY or choose to entrust your boat to our team, now’s the time to act. Let winter work for you—not against you.