If you live where it drops below freezing and your boat is more complex than a dinghy, you need to winterize. Failing to winterize can cost yourself money and time with avoidable repairs and make you miss the start of the boating season. You'll want to learn from these mistakes.
If You Don't Winterize Your Boat, Here's What Happens: Water freezes and expands and can damage anything it's trapped inside. Water may seep into unprotected spaces to do this. Acidic and corrosive wastes, salt and corrosion buildup can damage delicate parts in engines. Fuels break down or grow dirty. Mold and mildew take root, and you may come back to a boat in the spring that you can not use because of multiple system failures.
System by system, there's a lot that can go wrong, and most of it is about water freezing where it doesn't belong. Below, We'll go over each potential complication in depth.
Winterizing includes most of the following, though the exact list will depend on your boat and there may be additional tasks.
Draining everything that holds water, from plumbing lines and tanks to engine blocks and cooling systems.
Flushing everything out that comes in contact with salt water.
Adding non-toxic antifreeze to everything that held water including plumbing, toilets, fixtures, engines and bilges.
Changing oil in engines and fogging them with oil.
Draining gasoline tanks and/or treating with stabilizer
Filling diesel takes and treating with antimicrobial stabilizer
Disconnecting batteries and charging them (lead acid) or discharging them to 50% (LiFePO~4~).
Covering the boat or moving it indoors.
With all that to do, what could possibly go wrong?