DIY Boat Winterization: Budgeting for Annual Maintenance

It’s the end of the season and time to put away the Hawaiian shirts and water skis. The days are getting shorter. There’s a chill in the evening air. Days on the boat will soon be precious memories, it’s time to winterize your boat. Fall lay-up is quite possibly the single most important maintenance duty a boater will perform. Proper winterization will prevent costly damage that can result from freezing, dormancy, corrosion and moisture, and will allow for a smooth launch come springtime.

Without fogging the cylinders with fogging oil, severe rust may occur. Without flushing the cooling system or draining the gear oil case, trapped water can freeze, expand and destroy the expensive housing. Three or four hours of work and some inexpensive maintenance materials and tools can get the job done right.

Here is a fairly comprehensive list to guide you through the process. Depending on what type of boat you have, some of this may not apply, but for most boats, following these steps will provide safe haven for your boat and all of its parts throughout the winter. All of the materials are available at your local boating supply store.


  • Clean your boat and apply a rust inhibitor on the metal hardware and on your steering and control cables.
  • Use "No Damp" or other mildew control bags or buckets throughout the cabin and any enclosed lockers or compartments


  • Drain the fluid from your engine block and manifolds, water pumps and coolers. Consult your engine manual for the location of all of the drain plugs.
  • Drain and fill the gearcase with gearcase lubricant.
  • Drain Porta-Potty and fresh water system. Add freshwater antifreeze to water tank and Porta-Potty


  • Fill up the gas tank and stabilize with additives. Run the engine for approximately 15 minutes to ensure that the additive reaches the gasoline in your fuel lines.
  • Pump antifreeze into the supply lines that lead to the faucets and shower.
  • Fill block, manifold, and circulating pump with propylene glycol antifreeze (-200 antifreeze is best for engines).
  • Backwash the cooling system and lower unit of the sterndrive to get rid of salt, sediment and rust flakes, by using an earmuff style flushing kit that clamps onto the water intake. Use a winterization kit to pull antifreeze into the cooling system.


  • Replace the fuel-water separator.
  • Change oil and oil filters.
  • Inspect belts and hoses, replace if necessary.
  • Replace any sacrificial anodes (zincs in saltwater, magnesiums in fresh water) that are less than half of their original size.


  • Grease the sterndrive gimbal bearing and engine coupler.
  • Inspect and lubricate steering and trim.
  • Grease your trailer bearings.


  • Test run the engine and spray fogging oil on the cylinders until the engine stalls. This protects the inside parts from corrosion.


  • Sand down and repaint the lower unit to prevent rust.

Take Home

  • Remove the battery and store it in a safe dry place. Check battery fluid levels.
  • Remove interior cushions and jumpseats and store in a cool, dry place. Otherwise, place the cushions on ends to allow for maximum ventilation, thereby reducing mildew damage.
  • Be sure to remove any food or drink from the boat. Rodents cannot refuse that Snickers bar and love to rear their young in boats. Also remove any charts, linens, electronics that could be damaged by moisture.


  • Store boat in a garage or other temperature controlled facility if possible. If not, cover the boat with shrink-wrap or a large tarp.
  • If your boat is stored on a trailer, block the wheels so they are off the ground and loosen tie-down straps to reduce stress on the hull.
  • Store your inflatables away from rodents, who love to eat hypalon and PVC fabrics. Also, do not leave the inflatable exposed to the elements - clouds do not inhibit UV rays.


Category: Sailing , Day Cruising
Tags: Winterizing Products