Preparing boats for winter is one of the most important things boat owners can do. Winterizing boats will protect the boat engine, cooling system and more. It’s critical to keep your boat running. It will also prevent serious damage and insurance claims. But once the seasons change you need to undo all that work. Luckily it is not that hard to dewinterize your boat.

If you follow a simple checklist you should be able to easily get your vessel ready for the new season. Always remember to check your owner’s manual before winterizing and dewinterizing. It may have specific tips and instructions that are unique to your boat and your engine. This can change from an outboard motor to an sterndrive. Make sure you follow specific instructions for outboard or inboard as necessary. These should always supersede any general info you find on the internet.

General Steps to De-winterize Your Boat

  • Start by taking the boat cover or tarp off. If you had your boat shrink wrapped, carefully remove it.
  • Give the vessel a quick look for insects, rodents or birds. If the boat had an opening, creatures may have taken up residence over the winter. An ultrasonic pest repeller placed on the boat can help clear out stowaways. This is an effective and chemical-free option.
  • Give a quick inspection of the hull for any damage, mold or mildew. Check the deck as well.
  • Make sure you have your registration and relevant documents. Secure them on board.
  • You need to check all the cables and hoses on your boat. Anything rubber parts or plastic parts susceptible to cold weather damage. Give them a visual inspection and flex any that are flexible. You’re looking for visible cracks of any kind.
  • Freeze damage can be severe. It can often be easily identifiable with a visual inspection. Water can expand by volume up to 9% when it freezes. This can cause pipes, lines, and hoses to burst. Water contamination in an engine can expand to the point that the engine block cracks.
  • Clean any vinyl and canvas surfaces. A gentle cloth or sponge with warm water and soap can do the job. Clean any carpeting as well. A shop vac can help make short work of this.
  • Check the steering to see if it’s stiff. The power steering cables will stiffen up over the winter. Get the wheel moving to loosen it up some. Don’t force it if it’s too stiff. That can cause more damage. There may be a blockage in the steering tube.

Check the Hull

  • Look over the hull for any damages. Scratches, scrapes, holes and more should be fixed up.
  • Do a full hull cleaning with a mild detergent. You can use a power washer for this job but make sure it’s not too intense. You don’t want to risk damage to the hull.
  • Refinish any blisters
  • Check and replace zincs
  • Test the trim tabs
  • Inspect the ladder or swim platform
  • Check the rudder and fittings
  • Inspect the rub rails
  • Check the shaft, cutlass bearings, strut and prop
  • Touch up the paint
  • Clean and scrape the bottom of the boat. Paint it with antifouling paint to prevent rot.

Check the Deck

  • Check around the deck, windows and port lights for leaks
  • Clean and grease the winches
  • Check chainplates and cleats
  • Inspect the stanchion, pulpits and lifeline
  • Lubricate the anchor windlass
  • Lubricate blocks and pad eyes
  • Check the dinghy or lift raft

Check the Boat Engine and Fuel System

  • Perform an engine oil change and replace the oil filter
  • Make sure you’re using the correct oil and additives. Check the owner’s manual if you’re not sure what oil you need.
  • Check and change the fuel filter if it needs replacement
  • Make sure you have spare oil filter and fuel filter in board
  • Look over the fuel lines for cracks and leaks
  • Check the fuel and replace if necessary. If you didn’t add a fuel stabilizer to the gas tank during the winterization process, change it now. The fuel will likely have suffered fuel separation. Replace it with the proper e10 gas
  • Check and change the engine zincs
  • Check your engine belts. Any cracks will mean it needs to be replaced. Push on the belts slightly with your fingers. When belts feel loose it means they have lost tension. Loose belts should be replaced.
  • Check transmission fluid
  • Clean backfire flame arrestor
  • Clean the water strainer
  • Check the impeller and replace the water pumps if necessary
  • Inspect the bilge blower
  • Replace spark plugs
  • Check spark plugs cylinders and wires
  • Lubricate and spray parts
  • Change the gear lube
  • Remove the distributor cap and check the state of the distributor. Look for corrosion. Replace the distributor cap if necessary
  • If you winterized your carburetor with a plastic bag over it, make sure to remove it now.
  • Start your engine to make sure it’s running properly. If you’re trying it out on land make sure you have water to add to the drive. Do another inspection for leaks once the engine is running.
  • When the engine is running check all the gauges again.

Check the Cooling System

  • Inspect the cooling system. Flush the coolant line if you didn’t do this before winterizing. If you did flush, you can now refill the system.
  • Mix your antifreeze 50/50 with water.
  • Check hoses for cracks and breaks

Check the Electronics

Marine Battery- Types and Maintenance Tips

  • Check the battery water levels
  • Top up with distilled water
  • Perform a battery check with a battery tester. Your battery should hold a charge of 13.2 to 13.4 volts. If it’s too low it may not work.
  • Clean battery terminals.
  • Inspect terminals for corrosion and clean them if necessary
  • Lubricate terminals
  • Test all gauges
  • Check bonding
  • Test the radio, GPS and other devices. Make sure everything not only turns on but works properly.
  • Inspect fuses and make sure you have spares
  • Check fixtures and lighting, including navigation lights
  • Check bonding system

Check the Water Systems

  • Flush the water tank
  • Check the pump for leaks
  • Inspect the hot water tank
  • Check the thermostat
  • Check for tank cap keys
  • Empty water separator filters
  • Clean shower sump pump screens
  • Add chemicals to the head system if necessary
  • Check Y-valve operation
  • Shock the drinking water tank. Pool shock is a better choice than bleach and can be cleared out faster.

Check the Bilge

  • Check the bilge pump itself. Look for any damage before moving onto other bilge pump parts.
  • Check the bilge pump circuits
  • Check the automatic switch
  • Inspect the area for any sign of mold and mildew from water that may have been missed.
  • Make sure the blower is running properly

Check Safety Gear

  • Make sure you have all PFDs and they are in good condition
  • Install new fire extinguishers
  • Check that you have all charts and they are up to date.
  • Check your sound signaling device
  • Make sure life rings or other devices are in good condition
  • Inspect the compass to make sure it’s working
  • Inspect navigation lights
  • Check your first aid kit. Replace any missing parts

Check the Sails and Rigging

  • Check sails for tears or chafing
  • Check battens and batten pockets
  • Inspect bolt rope
  • Look for damage to the mast
  • Check all rivets and screw connectors for signs of corrosion
  • Check the reefing points and gear
  • Inspect spreader boots and shrouds
  • Check the clevis pins and rigging and turnbuckles
  • Lubricate the roller furling
  • Check the halyards
  • Check the stays to see if they are fraying

Do a Trailer Check

Loading Boat on Trailer

  • Make sure the trailer registration is up to date
  • Check rollers and pads
  • Check safety chain
  • Check tongue lock
  • Clean and lubricate the winch
  • Lubricate wheel bearings
  • Test lights and electrical connections
  • Check your trailer tire pressure
  • Be Prepared

Dewinterizing your boat is a process. As you can see from this checklist, there is a lot to get done. You need to check your boat from top to bottom. It has to be this thorough if you want your boat to be safe and functional. If your boat is not properly winterized or dewinterized it can lead to problems. Things can break, wear out, and result in costly repair bills. Make sure you are thorough and patient. Don’t rush the dewinterizing process. Be prepared to spend a day getting this done. Bring some friends, pack some lunch and drinks, and try to enjoy yourself. When you’re done, you’ll be out on the water enjoying your boating adventures for another season.