Winterize Your Boat Right

By The BoatUS Editors

Get a fast start in the spring by putting your boat to bed properly before the winter freeze.

Photo of leaving the boatyard towing powerboatPhoto: Matthew Borkoski

Freshwater expands in volume when it freezes and can push outward with a force of tens of thousands of pounds per square inch. That expansion can crack an engine block, damage fiberglass, split hoses, or destroy a refrigeration system overnight. More than three-quarters of insurance claims for ice and freeze damage on boats involve cracks in the engine block or the exhaust manifolds that occurred because water remained in the engine or cooling system during a hard freeze. Follow the tips below so that winter damage doesn't spoil next summer's fun.

If Your Boat Is On A Trailer

  • Deter thieves. Nothing beats a gated, secure storage facility for the winter. But if that's not possible, park the trailer in a well-lit area with its tongue facing away from the street. Take off the coupler. Remove small outboards and store them somewhere secure; lock larger outboards with security locks.
  • Look up! Don't park your boat under overhanging tree limbs or near a steeply sloped roof.
  • Keep water out. Shrink-wrap your boat or use a cover to keep snow and ice from filling the cockpit and damaging the gelcoat or through-hull fittings. Make sure all ports and hatches are sealed.
  • Keep it dry. Leave the drain plug out so any water that does get in won't accumulate. Elevate the tongue to assist with drainage.
  • Save your tires. Take the tires off and block up the trailer. Store the tires and lug nuts indoors. This deters thieves and increases tire life by preventing flat spots and reducing exposure to damaging ultraviolet radiation.

If Your Boat Is In The Water

  • Secure your boat below the waterline. Close all below-waterline seacocks or gate valves except on cockpit drains. Remove the hoses attached to them and drain out the water. Use an absorbent towel or turkey baster to remove the water from valves so they don't freeze, and put the hoses back.
  • Cover up. Most boats sink in the winter when snow and ice fill the cockpit and the weight pushes fittings underwater that are normally above the waterline. A good cover will keep the snow and ice out while reducing the risk that debris will clog your cockpit drains.
  • Pump it out. Make sure the bilge is free of any debris or oil that might clog the pump or interfere with the switch. The bilge pump should be wired directly to the batteries (with a fuse) so it will operate when switches are turned off at the main panel. After you've cleaned the bilge, make sure the pump is working. Add enough nontoxic antifreeze to trigger the float switch and verify that it gets pumped out, then bail or sponge up the remainder.
  • Protect your lines. Ready-made polyester chafe protectors are available from marine chandleries, or you can make your own out of heavy-duty polyester and hook-and-loop fasteners. If your boat is tied to pilings, consider using TideMinders or other systems designed to allow the line to slide easily up and down the piling without getting caught.
  • Tie up right. Center the boat in the slip and use long docklines and springlines led at shallow angles to keep the boat well away from the dock.

How To Prepare Your Outboard Engine

  • Attend to the fuel. The engine's gas tank must be either filled and treated with stabilizers or drained completely.
  • Flush the engine. Follow the manufacturer's instructions. Sometimes this doesn't involve running the engine at all; many newer engines have a garden-hose fitting that allows for a quick flush without starting the engine. Check the manual for details.
  • Change all engine lubricants. The engine's lubricants (engine oil for four-stroke outboards, and lower-unit gear lube for all outboards) should be drained and refilled; change the fuel and oil filters.
  • Fog the engine. After treating the fuel and running the engine for a few minutes, the engine should be fogged with a storage lubricant. With the engine running, inject fogging oil through the carburetors or the air intakes of the electronic fuel-injection system in such a way as to coat the engine with oil until it begins to smoke, then continue fogging it until it stalls. Consult the manual. Fogging can also be done with the engine shut down; to do this, remove the spark plugs, then spray oil into the cylinders, rotating the flywheel to distribute the oil.
  • Leave the engine in the running position. Store the engine tilted down, as though it were operating; otherwise, water that gets in through the hub can freeze and crack the lower-unit housing. 

— Published: Fall 2015

Ice Coverage

Photo of covered boats in winter

Even the best of preparations sometimes fall short. Protect yourself from damage by adding ice and freezing coverage* to your BoatUS Marine Insurance policy for as little as $25 per engine.

*Ice & Freezing coverage add-on available until October 31, and with the BoatUS Yacht & PWC Policies only. In the state of California, the BoatUS Marine Insurance Program is provided through Boat Owners Association Insurance Services, CA License # 0H87086



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