Winterize your sailboat – Part 1

Winterize your sailboat – Part 1

How to prepare your boat for winter
without paying a fortune to your marina

Click here for PART 2


If you have to lay up your boat during the winter due to the freezing weather, there is just one objective to the whole process – you must remove all fluids from the boat, or protect them from freezing by the addition of anti-freeze.

Everything else is secondary.

Frozen water, whether it’s in your water lines, engine, batteries, heater tank, bilge, toilet or anywhere else on the boat will cause serious damage.

And remember, your insurance policy may not cover any damage caused by lack of maintenance.

The first step to winterizing your boat is: Check your Owners manual (if you have one) for any specific requirements.

Then proceed to step 2:

Prepare a checklist

You need to prepare a comprehensive checklist of the work to be done, and the sequence in which it needs to be done, otherwise you’re sure to forget something. So take a pencil and paper and start an initial list as you read on.

You can follow the steps noted below, or make your own sequence. Just make sure you cover all the bases.

1. Clean out the boat

  • Remove all electronic equipment and store it in a warm dry place. Check your owner’s manual for info on how to store this gear
  • Remove all sails, lines, anchors, fenders, pfd’s, bunk cushions, flares, fire extinguishers, carpets etc. Check and repair these over winter.
  • Empty all lockers, especially food lockers. Take all loose gear off the boat.
  • Securely prop open all locker doors, access hatches, bilge access and anything else that will improve air circulation.
  • Open and clean the ice box and/or refrigerator.

2. Drain all the water from the fresh water system

  • For a fairly simple system, drain all the hoses and drain and clean the tanks. Leave everything empty
  • For more complicated systems with heaters and electric pumps you’ll need empty all water, header and heater tanks, making sure that no water remains in the tanks below the outlet level. Clean the tanks and wipe internally with a chlorine solution.
  • Make sure you disconnect the electrical supply to the heater tank before you drain it.
  • Drain all the water from the hoses and pumps – you may need to disconnect hoses at both ends to do this.
  • Reconnect hoses and bypass the heater tank. Pump pink, eco-friendly anti-freeze into the hoses and pumps to protect them from any residual water
  • Check shower sump for water. Sponge dry if necessary.

3. Drain and winterize the head

  • Pump out the holding tank. Flush the head with fresh water several times while emptying the holding tank.
  • Close the head intake seacock and remove the hose. Sit the hose in a bucket of 50-50 eco-friendly (pink) ant-freeze and water.
  • Pump the head until all water in the bowl and hoses has been replaced by anti-freeze. Replace the hose on the seacock.
  • Don’t open the seacock.

4. Winterize the batteries

  • Remove the batteries to a warm dry place. Keep them off the ground.
  • Fully charge the batteries before storage and recharge every month in storage.
  • Don’t leave the batteries connected to the charger.

Winterize your diesel inboard engine

1. The fuel system

  • Add stabilizer/ biocide to your fuel tank and fill the tank. Read the instructions on the stabilizer container.
  • Change all fuel filters and drain the water separator.
  • Run the engine for 15 minutes to get stabilized fuel into all lines and injectors
  • If already on the hard, run a water hose to the raw water intake to get cooling water to the engine.

2. The oil system

  • Drain the oil while the engine is still hot from the fuel circulation above
  • Change the oil filters
  • Fill engine with clean oil
  • Drain the oil in the transmission if separate from the engine. Refill with clean oil

3. The fresh water cooling system

  • Drain the fresh water cooling and heat exchanger system and replace the coolant with 50-50 pink antifreeze and water.
  • Winterize the raw water side as detailed below

4. Flush the raw water cooling system

  • Close the raw water seacock
  • Disconnect the hose on the outlet side of the raw water pump
  • Place the end of this hose into a large bucket. Have a second bucket handy.
  • On the exhaust riser or muffler, disconnect the cooling water hose.
  • Connect this hose to a water supply and back flush the raw water system.
  • Collect the flushing water in the buckets and dispose of properly.
  • Reconnect both hoses.

5. Replace the raw water with anti-freeze

  • Close the raw water seacock
  • Disconnect the hose from the seacock
  • Place the hose in a bucket of 50-50 mixture of pink anti-freeze and water
  • Start the engine and run it until pink anti-freeze is discharged from the exhaust
  • Turn off the engine and reconnect the hose to the seacock.
  • Do not open the raw water seacock
  • Drain the anti-freeze from the muffler if you have a drain plug. Reinstall this plug immediately.
  • Remove the raw water impeller and store. Tag the engine so you remember the impeller is not installed.

If you are already on the hard you can leave the seacock open and run a hose from the raw water intake to a bucket of anti-freeze mixture and proceed as above. Close the seacock afterwards.

6. Sundry work

  • Spray fogging oil into the intake manifold and turn the engine over by hand. Don’t use the starter motor
  • Spray the inside of the ignition switch with WD-40 or CRC.
  • Cover the engine with a waterproof cover to protect from any leaks above
  • Seal all air intakes, breather pipes, tank vents and exhaust outlet with duct tape or plastic seals.
  • Inspect fuel tank, lines, pump and filters for leaks

Winterize your gasoline inboard engine

Follow steps 2-5 above

7. The fuel system

  • Start engine and shut off the fuel supply.
  • Spray fogging oil into the air intake while engine is running.
  • Run engine until it stops.
  • Drain the gasoline tank and all gasoline lines. Ethanol in modern fuel absorbs moisture.

8. Sundry work

  • Spray the inside of the ignition switch with WD-40 or CRC.
  • Cover the engine with a waterproof cover to protect from any leaks above
  • Seal all air intakes, breather pipes, tank vents and exhaust outlet with duct tape or plastic seals.
  • Inspect fuel tank, lines, pump and filters for leaks

Clean and inspect your boat

1. Internal clean

  • Remove all loose gear from the boat.
  • Wash down all surfaces to remove any dirt or grease that will allow mould to grow.
  • Scrub the ice box and/or refrigerator with a mild bleach solution
  • Clean out the interior of all lockers.
  • Clean the bilge. Scrub with soap and hot water. Add pink anti-freeze to bilge to stop any remaining water from freezing.

2. External clean

  • Scrub or pressure wash the hull and deck.
  • Clean hardware, mast and rigging to remove salt and grime.
  • Touch up any damaged varnish or paintwork
  • Lightly wax all fiberglass surfaces to protect over winter.

3. Inspect the hull

  • Inspect the hull for cracks, blisters or any stress cracks. Repair as necessary
  • Inspect the deck for cracks. Check for delamination at cracks and repair if required
  • Install backing plates to hardware or staunchions showing signs of stress cracking before repairing
  • Inspect lifelines for signs of corrosion. Replace if necessary.

4. Inspect sundry systems

  • Inspect propane lines for damage. Make sure they are well supported.
  • Close propane bottle and light stove. Allow stove to go out. Close off the supply at the stove.
  • Remove propane bottles from the boat. Seal the end of the propane line.
  • Inspect all fuel supply lines for softness, brittleness or cracking.
  • Inspect fuel fill line and fuel vents. Check all joints for leaks.
  • Ensure all lines are well supported with clips or straps.
  • Inspect and service all winches, mainsheet system, turning blocks and rope clutches.
  • Lubricate the roller furling system if fitted
  • Inspect and service all seacocks
  • Inspect all hoses and hose clamps. All hoses should be double clamped. Replace as necessary.
  • Inspect all electrical connections. Clean and reconnect if required