Last Updated: November 22, 2025
“Winterizing” means something different when you’re lucky enough to sail in Southern California. While our friends on the East Coast are shrink-wrapping their hulls and heading for dry dock, San Diego boaters are preparing for the rainy season, increased humidity, and shorter days.
At Sail San Diego, we’ve spent 30+ years maintaining the largest fleet of modern sailing yachts in the harbor. Even though our private sailing charters run year-round, we know that many local boat owners use their vessels less during the cooler months.
To help your boat stay in peak condition until spring, here are the five highest-priority maintenance steps for the San Diego winter.
1. Prevent Hull Erosion & Mildew: The Deep Clean
During a San Diego winter, the combination of the morning marine layer and cooler nights creates a breeding ground for mildew.
- Top to Bottom: Wash your boat inside and out. Removing salt spray from the summer prevents the “salt crust” from etching into your gelcoat during the rainy season.
- Fiberglass Check: Inspect for any blistering. If you catch these early, they are simple repairs; if left through a wet winter, they can become costly structural headaches.
- Canvas Care: Don’t forget your bimini tops, spray sheets, and window screens. Clean and dry them thoroughly before the first major Pacific storm hits.
2. Marine Engine Care: Flush Your Cooling System
For boats with raw water cooling systems, salt is the enemy. Even if you aren’t pulling your boat out of the water, flushing the system is vital if the boat will be sitting for weeks at a time.
- Freshwater Flush: Flush the engine with fresh water to remove salt, dirt, and impurities that cause internal corrosion.
- Extreme Climate Note: While rarely necessary for local coastal residents, if you keep your boat inland where temperatures can dip toward freezing, you should run marine-grade antifreeze into the cooling system and cylinder block.
3. Fuel System Stabilization: Fighting Humidity
In San Diego, the biggest winter fuel threat isn’t freezing—it’s condensation. Our fluctuating day/night temperatures can cause moisture to form inside a half-empty tank.
- Top It Off: It is a best practice to keep your fuel tank full during the winter to minimize the “air space” where condensation forms.
- Stabilize: Add a marine-grade fuel stabilizer to prevent the fuel from breaking down.
- Filter Change: Replace your fuel filters at the end of the peak season to ensure no trapped water or debris lingers in the system.
4. Protect Your Inboard or Outboard: The Oil Change
Don’t wait until your first Spring Break sail to change your oil. Used engine oil contains acids and moisture that can pit and corrode engine bearings if left to sit all winter.
- Flush Impurities: Change the oil and oil filter on stern drives, inboards, and four-stroke outboards now.
- The “Milky” Sign: As you drain the gear case, watch for a milky color. This indicates water intrusion and means you likely have a leaking seal that needs professional attention before next season.
5. Corrosion Protection: Lubricate Moving Parts
The salty air in San Diego Bay is relentless. When a boat sits unused, hinges, latches, and steering systems can seize up.
- Small Systems: Use a moisture-displacing lubricant on all hinges, latches, and snaps.
- Critical Linkages: For boats being trailered or stored, ensure all throttle and shift linkages are well-greased.
Experience the San Diego Winter on the Water
Winter is actually one of our favorite times to be out on the water—the bay is quiet, the air is crisp, and whale watching season is in full swing!
If you’d rather spend your time sailing than scrubbing, let us take the helm. Join us for an intimate sunset charter on one of our meticulously maintained yachts and see why we’ve been San Diego’s premier boutique sailing company for over three decades.