Winterizing -An Important Step to Your Boat’s Longevity

Image of a row boat with a snowman inside on a frozen waterbody

Winterize your boat before costly damage occurs.

The forecast for this winter appears to be mild, but it only takes one good freeze to do expensive damage to a boat’s engine.  The Marine Board offers the following steps to the do-it-yourselfers who boat seasonally to help prevent costly repairs, later.  For those less mechanically inclined, many marine stores will winterize your boat with a varying cost depending on the type and class of boat.

Your Boat

  • If possible, store your boat ashore for the winter.  The bulkhead, keel, and motor are the critical areas needing support.  Cradles work best, but don’t store your boat on a cradle that wasn’t designed for the boat you have.
  • If you store your boat in the water, make sure to close all through-hull fittings, gate valves, and seacocks to keep the water out.  As water freezes, it expands and can break these important features.  Also, plug any exhaust ports. Do not, however, close cockpit drains.  Check on your boat occasionally to make sure lines are secure and the bilge remains dry.
  • Make sure to cover your boat.  Use a frame under the cover to prevent water from pooling or tearing the cover.  Canvas is best because it breathes.  If you use plastic, make sure you leave vents in it to allow any moisture to escape.  Allow for drainage if you’re storing outside.
  • Add non-toxic antifreeze to water tanks, toilets, and septic holding tanks.  Never use engine antifreeze in a freshwater system.
  • Make sure to remove any electronic equipment, important documents or other valuables.  Marinas are more like ghost yards in the winter, and tempting to thieves.

Your Engine

    • Drain the cooling system and add anti-freeze.  On outboards, this means filling a large bucket or drum with enough antifreeze fluid to reach the water intake, then running the motor until it is warm.  Use non-toxic antifreeze only.
    • Disconnect the battery and store in a warm, dry place. If you have to leave it on board to operate an alarm or bilge pump, fill battery cells with distilled water and fully charge it so it doesn’t freeze.  Apply petroleum jelly to clean terminals to prevent corrosion.
    • Oil: Drain and replace the engine, transmission and outdrive oil. Replace gear oil in outdrives.  Use internal oil fogger when the engine is warm to prevent corrosion.
    • Top off fuel tanks, leaving a little room for expansion.  Add a fuel stabilizer.
    • To keep water from collecting in outdrives; leave them in the down position.
Image of a winterized boat kept at Key Storage in Portland, OR.

Winterized boat kept at Key Storage in Portland, OR.

For more tips on winterizing your boat and trailer, visit


The Marine Board is funded by registration, title fees and marine fuel taxes paid by motorized boaters.  No lottery, general fund tax dollars or local facility parking fees are used to support the agency or its programs.  Boater-paid fees go back to boaters in the form of boating safety services (on-the-water enforcement, training, and equipment), education/outreach materials and boating access facility grants (boat ramps, docks, parking, construction, and maintenance).  The Aquatic Invasive Species Prevention Permit program is dedicated funding to pay for border inspection stations, decontamination equipment, inspectors, and signage/outreach materials.  The Mandatory Education Program is self-supporting and revenue helps pay for education materials and boater education cards.  For more information about the Marine Board and its programs, visit

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