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Winterizing – What to Expect

Recognizing that many readers are in warmer climes or have boats that don’t need special winter preparation, we present this for those not so fortunate. Torresen Marine will have more than 600 boats in storage for the winter months. Most of these boats require special care to prevent damage from freezing water. Our standard winterizing covers some or all of what is listed below. If you do the job yourself or have it done elsewhere, this checklist will help to know what needs doing and what results to expect. Always keep in mind that the only freeze damage you can expect is the result of freezing water.


Winterize air conditioner:
Shut off cooling water inlet valve for each unit.
Pump potable antifreeze through system/s.
Reopen seacocks when boat is hauled.

Winterize bilge pumps:
Pump bilge dry.
Put potable antifreeze in remaining water.
Pump antifreeze through the pumps.

Winterize the engine/s:

Fresh water-cooled engines:
Check status of existing antifreeze.
Adjust mixture if slightly deficient.
Change antifreeze mixture if grossly deficient. (added cost)
Bleed air from system if required.
Shut off seacock.
Pump potable antifreeze through system, including inlet strainer, until it can be seen discharging overboard.
Reopen seacock when boat is hauled.

Sea water-cooled engines:
Shut off seacock.
Drain water from the engine block and manifold.
Resecure drains.
Pump antifreeze through the cooling system until it discharges overboard.
Reopen seacock when boat is hauled.

Winterize generator:
Same as Winterizing engine/s

Winterize head:
Assure holding tank has been pumped out.
Shut off sea cock.
Pump system to dry bowl.
Pump antifreeze through the system.
Reopen seacock when the boat is hauled.

Winterize out board motor:
Drain water from the engine.
Check lower unit lubricant.

If lower unit shows signs of water – drain the lower unit.
Check lower unit seals.
Replaced seals if necessary.
Refill lower unit with proper gear oil.

Winterize the refrigeration:
Air-cooled units require no winterization.
Shut off sea cock.
Pump potable antifreeze through the system.
Reopen seacock when the boat is hauled.

Winterize the water system:
Drain the water heater – if installed.
Bypass the water heater.
Drain the water tanks.
Pour potable antifreeze into the tanks.
Pump the antifreeze through the system assuring that it comes out of all possible places.

(Galley and head sinks, foot operated spigots, cockpit shower, etc.)

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This entry was posted on Monday, October 29th, 2007 at 12:55 pm and is filed under Main Stories, Winterization. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

3 Responses to “Winterizing – What to Expect”

  1. Max Robinson Says:

    What is danger of seacocks freezing? These are bronze valves put in by boat manufacturer and boatyard.

  2. Brian Torresen Says:

    The danger is not of your seacocks freezing. The danger is of water trapped in your closed seacocks freezing. If your seacocks are left closed, any water that remains above the valve can freeze and could crack your bronze valves.

  3. Rick Says:

    I winterized my sterndrive engine….

    I made my own winterizing kit:
    1 Washing machine hose
    1 Male/Male garden hose adapter to attach the hose to the ear muffs.
    1 Green colored recycling bin with out drain holes, or a 5-gal pail will work.
    1 ball-valve, 2 garden hose rubber washers.

    I took my green recycling bin (without drain holes in the bottom) and drilled a 1/2″ hole in the side. Attached a ball-valve, rubber washer on each side of container.. that attaches to a washing maching hose. I take the washing machine hose, attach one end to the ball valve, the other end to the “ear muffs” that attach to the lower leg. Place the bin, hose attached on the transom and fill with NON-TOX antifreeze, attach the ear muffs. Start the engine, open the ball valve and fill’er up with antifreeze. The antifreeze fills the engine by gravity feed. It cost me $15.00 for materials at Home Depot instead of the 50. bucks West Marine was going to charge. I used this last year, and today, still works well.

    In the summer months, I use the bin to hold soapy water to wash the boat/truck. When finished, I store fogging oil, hose and other winterizing things in the bin for the winter. This system was pure “Yankee ingenuity” as we say in New England, and some friends have made the same for their boats & jet skis.


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